protein

[dàn bái zhì]

chemical substances

Collection

zero Useful+1

zero

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Protein is everything that makes up the human body Cells , an important component of the organization. Protein is converted into Fat The acidity of blood is increased.^[8] All important components of the body need protein participation. Generally speaking, protein accounts for about 18% of the total mass of the human body. The most important thing is that it is related to life phenomena.

Protein is the material basis of life, is an organic macromolecule, is the basic organic matter that constitutes cells, and is the main undertaker of life activities. There is no life without protein. amino acid It is the basic unit of protein. It is a substance closely linked with life and various forms of life activities. Protein is involved in every cell and all important components of the body. Protein accounts for 16%~20% of human body weight, that is, a 60 kg adult has about 9.6~12 kg protein in his body. There are many kinds of proteins in the human body with different properties and functions, but they are all composed of more than 20 amino acids (Amino acid) in different proportions, and are constantly metabolized and updated in the body.^[6]

Chinese name: protein
Foreign name: protein
Alias: Prion

Composition: More than 20 amino acids
Structure: Level I - Level IV
Formation mode: dehydration synthesis
Average molecular weight: The average molecular weight of 20 amino acids is 128

catalog

Basic meaning

Announce

edit

Protein tetramer

Protein is a substance with a certain spatial structure formed by twisting and folding of polypeptide chains composed of amino acids in the way of "dehydration and condensation".

The protein must contain carbon 、 hydrogen 、 oxygen 、 nitrogen Element, which may also contain sulfur 、 phosphorus And other elements.

Protein is composed of α- amino acid Combined in a certain order to form a polypeptide chain, and then combined by one or more polypeptide chains in a specific way Polymer compound 。 Protein is the scaffold and main substance of human tissues and organs, which plays an important role in human life activities. It can be said that there is no life activity without protein.

Male protein deficiency needs more attention than female protein deficiency. Once male protein deficiency occurs, it will lead to male sperm Male infertility is caused by the decrease of quality, sperm vitality and sperm liquefaction.

α General structural formula of amino acids^[7]

protein It is a complex organic compound, formerly known as“ Prion （ru ǎ n）”。 Amino acid is the basic unit of protein composition. Amino acid is linked into peptide chain through dehydration and condensation. Protein is composed of one or more polypeptide chains Biomacromolecule Each polypeptide chain has 20 to hundreds of amino acid residues (- R); Various amino acid residues are arranged in a certain order. The amino acid sequence of the protein is encoded by the corresponding gene. In addition to the 20 basic amino acids encoded by the genetic code, some amino acid residues in the protein can also be Post translation modification The chemical structure changes to activate or regulate proteins. Multiple proteins can be combined together, often to form stable protein complexes, fold or spiral to form a certain spatial structure, so as to play a specific function. Synthetic polypeptide Organelle It is the ribosome of rough endoplasmic reticulum in cytoplasm. Proteins differ in the type, number, order of amino acids and the spatial structure of peptide chains.

The ingested protein is digested, hydrolyzed into amino acids and absorbed in the body to synthesize the protein needed by the human body. At the same time, the new protein is constantly metabolized and decomposed, always in dynamic balance. Therefore, the quality and quantity of food protein and the proportion of various amino acids are related to the amount of protein synthesis in the human body, especially the growth and development of adolescents, the prenatal care of pregnant women, and the health and longevity of the elderly, which are closely related to the amount of protein in the diet. Protein is divided into Complete protein and Incomplete protein 。 Proteins lacking essential amino acids or having little content are called incomplete proteins, such as those contained in cereals, cereals, corn and animal skins and bones gelatin Etc.

Encyclopedia x confusion: graphical proteins

Correlation calculation

Announce

edit

Atomic number

From m amino acids, n strip Peptide chain Protein molecule, at least containing n One - COOH, containing at least n Nr. - NH two , peptide bond m - n , O atom m + n .

molecular mass

Let the average relative molecular weight of amino acid be a , with b Disulfide bond ， Relative molecular weight of protein= ma -18( m - n )-2 b

Gene control

Genetic nucleotide ：6

Messenger RNA Nucleotides in: 3

Amino acid in protein: 1

Composition and characteristics

Announce

edit

Protein is composed of C（ carbon ）、H（ hydrogen ）、O（ oxygen ）、N（ nitrogen ）Composition, general protein may also contain P（ phosphorus ）、S（ sulfur ）、Fe（ iron ）、Zn（ zinc ）、Cu（ copper ）、B（ boron ）、Mn（ manganese ）、I（ iodine ）、Mo（ molybdenum ）Etc.

The composition percentage of these elements in protein is about 50% carbon, 7% hydrogen, 23% oxygen, 16% nitrogen, 0~3% sulfur and other trace elements.

(1) All proteins contain nitrogen, and the nitrogen content of various proteins is very close, Average 16% ；

(2) Protein coefficient: every 1g of nitrogen in any biological sample means that about 100/16=6.25g of protein exists, and 6.25 is often called the protein constant.

Overall structure

Protein is a biopolymer composed of amino acids. The sequence of amino acids on protein molecules and the resulting three-dimensional structure constitute the diversity of protein structures. Protein has primary, secondary, tertiary and quaternary structures. The structure of protein molecule determines its function.

Chemical bond of protein molecule

Primary structure: The sequence of amino acid residues in the protein peptide chain is called the primary structure of the protein. Each protein has an independent and exact amino acid sequence. Peptide bond is the main chemical bond connecting amino acid residues in the primary structure, and some proteins also include disulfide bond.

Secondary structure: peptide chains in protein molecules are not straight chains, but curl according to certain rules (such as α- Spiral structure) or folding (such as β- Folding structure) forms a specific spatial structure, which is the secondary structure of protein. The secondary structure of protein mainly depends on the hydrogen bond formed between the hydrogen atom on the amino acid residue (- NH -) and the oxygen atom on the carbonyl group in the peptide chain. The forms of secondary structure are α- Spiral, β- fold, β- Corner, Ω - ring. among α- Spiral is a common secondary structure, and most of them are right-handed spiral. β- Folding is the formation of lamellar structure of polypeptide chain, which is zigzag. β- Corners and omega rings exist in globular proteins.

Tertiary structure: On the basis of the secondary structure, the peptide chain further forms a more complex tertiary structure according to a certain spatial structure. It is through this structure that the holes on the surface of myoglobin, hemoglobin, etc. exactly contain a heme molecule. The forces that maintain the tertiary structure of globular proteins include salt bond, hydrogen bond, hydrophobic interaction and van der Waals force, which are collectively called secondary bonds. In addition, disulfide bonds also play an important role in stabilizing the spatial structure of some proteins.

Quaternary structure: the aggregate structure formed by the combination of polypeptide chains with tertiary structure in a certain spatial arrangement is called the quaternary structure of protein. For example, hemoglobin is composed of four polypeptide chains with tertiary structure, two of which are α- Chain, the other two are β- The fourth order structure of the chain is approximately ellipsoidal.

Connection method

Using about 20 kinds of amino acids as raw materials ribosome The amino acid molecules are linked to each other to form peptide chains. Of an amino acid molecule amino And another amino acid molecule carboxyl , remove a molecule of water and connect it, which is called dehydration synthesis 。 Through condensation reaction carboxyl and amino The bond formed between two amino acid molecules is called Peptide bond 。 Compounds formed by peptide bond connection are called peptide 。

test method

Add 3ml egg white diluent and clean water to the two test tubes A and B respectively, and then add them to the two test tubes in turn Biuret reagent Fluid A and Fluid B. Observe the color change of solution in test tubes A and B. The above demonstration experiment results show that the biuret reagent reacts purple with the protein.

Physiological needs

Announce

edit

In 2000, Chinese Nutrition Society Revised the recommended dietary nutrient intake and newly revised protein Recommended intake As follows:

Recommended dietary protein intake for Chinese residents
Age (years)	Protein RNI/(g/d)		Age (years)	Protein RNI/(g/d)
Age (years)	male	female	Age (years)	male	female
0~	1.5~3g/(kg·d)		14~	sixty-five	sixty
0.5~	1.5~3g/(kg·d)		18~	-	-
1~	thirty-five	thirty-five	physical activity	-	-
2~	forty	forty	Light manual labour	fifty-five	forty-five
3~	forty-five	forty-five	Medium manual labor	sixty	fifty
4~	fifty	fifty	Heavy physical labor	seventy	sixty
5~	fifty-five	fifty-five	pregnant woman	-	-
6~	fifty-five	fifty-five	early stage	-	+8
7~	sixty	sixty	metaphase	-	+18
8~	sixty-five	sixty-five	advanced	-	+23
9~	sixty-five	sixty-five	wet nurse	-	+23
10~	seventy	sixty-five	old age	seventy-five	sixty-nine
11~	seventy-five	seventy-five	15% protein/total calorie

● RNI (recommended intake): It refers to the intake level that can meet the needs of most individuals (97%~98%) in a specific gender, age and physiological status group. Long term intake of RNI level can meet the needs of the body for this nutrient, maintain proper nutrient reserves in the tissue, and maintain healthy 。

Metabolic absorption

Announce

edit

Protein in gastric juice digestive enzyme Under the action of, it is preliminarily hydrolyzed to complete the whole digestion and absorption process in the small intestine. The absorption of amino acids through intestinal mucosal cells is carried out by the active transport system, which transports neutral, acidic and basic amino acids respectively. The protein digested and absorbed in the intestine is not only from food, but also from the shedding of intestinal mucosal cells and the secretion of digestive juice. About 70g of protein enters the digestive system every day, most of which is digested and reabsorbed. Unabsorbed proteins are excreted from the feces.

disease

Announce

edit

overdose

performance

The kidney needs to excrete the protein it eats. When protein is broken down, it will produce a lot of nitrogen, which will increase the burden on the kidney. Excessive intake of protein, especially animal protein, is also harmful to human body. First of all, excessive intake of animal protein will inevitably lead to more intake of animal fat and cholesterol. Secondly, too much protein itself will have harmful effects. Under normal circumstances, too much protein must be deammoniated and decomposed, and nitrogen is discharged from urine, which increases the metabolic burden. In addition, this process requires a lot of water, which increases the load on the kidney. If the kidney function is not good, the harm will be even greater. Excessive intake of animal protein also leads to excessive intake of sulfur-containing amino acids, which can accelerate the loss of calcium in bones and easily lead to osteoporosis.

harm

1. Once the protein is converted into fat in the body, the acidity of the blood will increase, which will consume a lot of calcium. As a result, the calcium stored in the bone will be consumed, making the bone brittle.

2. The kidney needs to excrete the protein it eats. When it breaks down the protein, it will produce a lot of nitrogen This will increase the burden on the kidneys.

ageusia

Protein deficiency occurs in both adults and children, but children in the growth stage are more sensitive. The common symptom of protein deficiency is the decline of metabolic rate, the decline of disease resistance, and the susceptibility to disease. The long-term effect is organ damage. The common symptoms are children's growth and development retardation, malnutrition, body weight decline, indifference, irritability, anemia, emaciation or edema, and secondary diseases due to susceptibility to infection. The lack of protein often exists together with the lack of energy, that is, protein heat malnutrition. There are two kinds of malnutrition. One is a nutritional disease that basically meets the energy intake but seriously lacks protein, which is called Kashika disease. The other is "emaciation", which refers to a nutritional disease with seriously insufficient protein and energy intake.

Usefulness

Announce

edit

1. Protein is an important raw material for building and repairing the body. The development of the human body and the repair and renewal of damaged cells are inseparable from protein.

2. Protein can also be broken down to provide energy for human life activities.

nature

Announce

edit

bisexual

Protein is composed of α- amino acid adopt Peptide bond It is a high molecular compound that exists in protein molecules amino and carboxyl , so follow amino acid Similarly, proteins are also amphoteric.

Hydrolysis reaction

Protein occurs under the action of acid, alkali or enzyme Hydrolysis reaction , via polypeptide , and finally get a variety of α- amino acid.

Proteolysis The key in the structure should be aligned“ Breaking point ”The peptide bond is partially or completely broken during hydrolysis.

Colloidal properties

Some proteins can be dissolved in water (e.g. chicken protein can be dissolved in water) to form a solution.

The molecular diameter of the protein reaches colloid Particle size (10 －9 ～10 －7 m) Therefore, the protein has colloidal properties.

precipitate

Reason: add high concentration neutral salt, organic solvent, heavy metal, alkaloid or acid, and a small amount of salt (such as ammonium sulphate 、 sodium sulphate It can promote the dissolution of protein. If concentrated inorganic salt Solution, which can make solubility And precipitate from the solution. This effect is called Salting out 。

In this way, the salted out protein can still be dissolved in water without affecting the properties of the original protein, so salting out is a Reversible process 。 Using this property fractional salting out Method can Separation and purification protein.

denaturation

Under the action of heat, acid, alkali, heavy metal salt and ultraviolet ray, the protein will change in nature and coagulate. This coagulation is irreversible and cannot be restored to the original protein. This change of protein is called denaturation. After denaturation, the ultraviolet absorption, chemical activity and viscosity of protein will increase and become easy to hydrolyze, but the solubility will decrease.

After denaturation, proteins lose their original solubility and physiological function. Therefore, protein denaturation and coagulation is an irreversible process.

Causes of protein denaturation

Physical factors include: heating, pressurization, stirring, oscillation, ultraviolet radiation, X-ray, ultrasound, etc.

Chemical factors include: strong acid, strong base, heavy metal salt, trichloroacetic acid, ethanol, acetone, etc.

Color response

Protein is composed of different amino acid residues, and the groups contained in these amino acid residues will also have some color reactions.

1. Ninhydrin reaction

The protein solution is mixed with ninhydrin dilute solution and heated. The solution is blue. All proteins can react with ninhydrin.

2. Diuret reaction

When protein solution is mixed with strong alkali solution and dilute copper sulfate solution, copper ion forms chelate ion with nitrogen atom and oxygen atom on two adjacent peptide bonds, which shows purplish red. This reaction is called biuret reaction of protein. Peptides and proteins above dipeptide can undergo biuret reaction

3. Protein yellow reaction

Protein containing phenylalanine, tyrosine and chromic acid residues will turn yellow after reacting with concentrated nitric acid, which is called protein yellow reaction. This is because the benzene ring in these amino acid residues undergoes nitration with concentrated nitric acid to produce yellow nitro compounds. This is the reason why skin and nails turn yellow when encountering concentrated nitric acid.

4. Miller reaction

When the protein containing tyrosine residue meets the nitric acid solution of mercuric nitrate, it turns red, which is called Miller reaction. This is because the phenolic hydroxyl group in the tyrosine residue forms a red compound with mercury ion. Because most proteins contain tyrosine residues, Miller reaction is universal.

Odor response

When protein is burned and decomposed, it can produce a special smell of charred feathers. This property can be used to identify proteins.

fold

The study of protein folding mechanism is of great significance for preserving protein activity, maintaining protein stability and inclusion body protein folding refolding. As early as the 1930s, China was a pioneer in biochemistry Wu Xian The professor is right Denaturation of protein After 30 years of explanation, Anfinsen Ribonuclease A According to the classical research of, unfolded proteins can be refolded spontaneously in vitro, only the sequence itself has included all the information of correct protein folding, and proposed the thermodynamic hypothesis of protein folding. For this reason, Anfinsen obtained the Nobel Prize in Chemistry 。 This theory has two key points: (1) the state of protein is in the balance between unfolding and natural conformation; (2) The protein with natural conformation is in the lowest energy state of thermodynamics. Although the amino acid sequence of a protein plays a central role in the correct folding of a protein, various factors, including Signal sequence ， Cofactor Molecular chaperones and environmental conditions will affect protein folding. New proteins are not all spontaneously folded and assembled into functional proteins. In most cases, they need the help of other proteins. Many folding enzymes and molecular chaperones involved in protein folding have been identified. The classic concept of "spontaneous folding" of proteins has changed and updated, However, this does not contradict the folded thermodynamic hypothesis, but improves the thermodynamic viewpoint in dynamics. In the process of protein folding, there are many forces involved, including some conformational space barriers, Van der Waals ， hydrogen bond Interaction, Hydrophobic effect , ion interaction, polypeptide Entropy driven folding generated by interaction with surrounding solvents, but we still know little about the specificity of the complex process of protein obtaining natural structure. Many experimental and theoretical work are deepening our understanding of folding, but the problem is still unresolved.

Early theories in the research of folding mechanism believed that folding was a gradual process from the denatured state to the natural state through the intermediate state, and in-depth research was carried out on folding intermediates, which believed that folding was carried out in a single way driven by thermodynamics. Later studies have shown that there are a variety of intermediates that can be measured experimentally in the folding process, and the folding is carried out through a limited path. The new theory emphasizes that there is diversity in the initial stage of folding. Proteins enter the folding funnel through many ways, thus folding is described as a funnel like image on the whole. The dynamic process of folding is considered as the progressive assembly of partially folded proteins on the whole, accompanied by changes in free energy and entropy, The protein finally finds its correct folding structure. This theory is called the energy picture. The concave and convex below the funnel reflects that the protein conformation instantly enters the region with the minimum local free energy.

The schematic diagram of the energy landscape, height represents the energy scale, width represents the conformation scale, there are other low energy states below the funnel, and the types of coexisting proteins in different energy states are also minimized.

This theory holds that proteins with the same structure can form similar natural conformation through different folding pathways, and the amino acid sequence of human acidic fibroblast growth factor (hFGF-1) and newt acidic fibroblast growth factor (nFGF-1) has about 80% Homology And has structural homology (12 β- fold Formation of reverse parallel arrangement β Folding bucket) at Guanidine hydrochloride In the process of induced refolding, hFGF-1 can detect a fusible sphere like folding intermediate, while nFGF-1 folds through two states (natural state to denatured state), and no intermediate is detected. The folding kinetics study also shows that the two proteins use different folding mechanisms. For the same protein, different osmotic regulators are used, and the way of protein folding is also different, indicating that different osmotic regulators have different effects on protein stability. These two examples both illustrate the complexity of the folding mechanism and are consistent with the theory introduced above.

physiological function

Announce

edit

Construct human body

protein

Protein is the material basis of all life, an important part of body cells, and the main raw material for human tissue renewal and repair. Every tissue of the human body: hair, skin, muscles, bones, viscera, brain, blood, nerves, endocrine, etc. is composed of proteins, so diet makes people themselves. Protein is very important for human growth and development.

For example, brain development is characterized by one-time completion cell proliferation The growth of human brain cells has two peaks. The first is when the fetus is three months old; The second is the period from birth to one year old, especially the period from 0-6 months old. By the age of one year, the proliferation of brain cells has basically completed, and the number has reached 9/10 of adults. Therefore, the requirements of 0 to 1 year old children on protein intake are very special, especially important for children's intellectual development.

Structural material

The human body is composed of billions of cells, which can be said to be the smallest unit of life. They are in the process of endless aging, death and regeneration. For example, the epidermis of young people is renewed once every 28 days, while the gastric mucosa is completely renewed in two or three days. So if a person's protein intake, absorption and utilization are good, then the skin is shiny and elastic. On the contrary, people are often in a sub-health state. After tissue damage, including trauma, failure to get timely and high-quality repair will accelerate the decline of the body.

Carrier transportation

Maintain normal metabolism of the body and transport of various substances in the body. Carrier protein It is vital to maintain the normal life activities of the human body. It can carry various substances in the body. such as hemoglobin ——Oxygen delivery（ red blood cell 2.5 million/s) Lipoprotein ——- Transport fat cell membrane The receptors on the Transporter Etc. Maintenance and composition

Maintain the balance of osmotic pressure in the body: albumin 。 Humoral acid-base balance 。 Constitute neurotransmitters acetylcholine , pentahydroxytryptophan, etc. maintain nervous system Normal functions of: taste, vision and memory.

Immunization of antibodies

yes white blood cell 、 lymphocyte 、 macrophage 、 antibody （ immunoglobulin ）、 complement 、 interferon Etc. Updated every seven days. When the protein is sufficient, the force is strong, and can increase 100 times in a few hours when needed.

Enzymatic catalysis

Various catalytic and regulatory functions necessary for human body enzyme 。 Our body has thousands of enzymes, each of which can only participate in one biochemical reaction. More than 100 biochemical reactions are carried out in human cells every minute. Enzymes can promote digestion, absorption and utilization of food. If the corresponding enzyme is sufficient, the reaction will proceed smoothly and quickly, and we will be energetic and not easy to get sick. Otherwise, the reaction will be slow or blocked.

Hormone regulation

It has the physiological activity of regulating various organs in the body. Insulin is synthesized from 51 amino acids. growth hormone It is synthesized by 191 amino acid molecules (independent of auxin).

collagen protein

It accounts for 1/3 of body protein and generates connective tissue , forming the skeleton of the body. For example, bones, blood vessels, ligaments, etc., determine the elasticity of the skin and protect the brain (a large part of brain cells are collagen cells and form blood brain barrier Protect the brain)

Energy material

Provide energy for life activities.

development history

Announce

edit

Globular protein (tertiary structure)

Protein was discovered in 1838 by Dutch scientist Glit Marder. He observed that living things cannot live without protein. Protein is a very important macromolecular organic matter in organism, accounting for 54% of the dry weight of human body. Protein is mainly composed of amino acids, and various types of proteins are formed due to different combinations and arrangements of amino acids. It is estimated that there are more than 100000 proteins in the human body. Life is an advanced form of material movement, which is realized through protein, so protein has extremely important biological significance. The growth, development, movement, heredity, reproduction and other life activities of the human body are inseparable from proteins. The movement of life needs protein, which is also indispensable.

Post translational protein transport

Some physiological active substances in human body, such as amines Neurotransmitter , polypeptide hormone antibody 、 enzyme 、 Nucleoprotein as well as cell membrane The proteins in the upper and lower blood that act as "carriers" are inseparable from proteins, which play an extremely important role in regulating physiological functions and maintaining metabolism. The composition of muscles in the human movement system and the metabolism of muscles in the process of contraction, work and action completion are all related to protein. Without protein, physical exercise is impossible.

In biology, protein is interpreted as a polypeptide formed by connecting amino acids with peptide bonds, and then a substance formed by connecting polypeptides. It is easy to understand that it is the scaffold and main material that constitute human tissues and organs. Protein deficiency: adults: muscle wasting, body immunity decline, anemia, and even edema in severe cases. Minors: growth stagnation, anemia, poor intellectual development, poor vision. Excess protein: protein cannot be stored in the body, and the body cannot absorb too much protein. Excess protein intake will lead to protein poisoning or even death due to metabolic disorders.

On October 30, 2021, the Feed Research Institute of the Chinese Academy of Agricultural Sciences announced that China has realized the synthesis from carbon monoxide to protein for the first time in the world, has formed an industrial production capacity of 10000 tons, and obtained the first new product certificate for feed and feed additives. The certificate was issued by the Ministry of Agriculture and Rural Affairs in August 2021, with the number of XSZZ (2021) 01.^[1]

In July 2022, Google's artificial intelligence company DeepMind further cracked almost all known protein structures. The database built by its AlphaFold algorithm now contains more than 200 million known protein structures, paving the way for the development of new drugs or new technologies to deal with global challenges such as famine or pollution Road.^[4]

classification

Announce

edit

Demand classification

The protein in food must be digested by the gastrointestinal tract and decomposed into amino acids before it can be absorbed and utilized by the human body. The human body's need for protein is actually the need for amino acids. The absorbed amino acids can only be used by the body to synthesize its own protein if they can meet the needs of the human body in both quantity and type. Nutritionally, amino acids are divided into essential amino acid and Nonessential amino acid Two types.

Essential amino acids refer to the amino acids that cannot be synthesized by the human body itself or the synthesis speed cannot meet the needs of the human body and must be ingested from food. For adults, there are 8 kinds of amino acids, including Lysine 、 methionine 、 leucine 、 isoleucine 、 threonine 、 valine 、 Tryptophan 、 Phenylalanine 。 For infants, there are 9 kinds and more histidine 。

The nonessential amino acids do not mean that the human body does not need these amino acids, but that the human body can synthesize them or get them from the conversion of other amino acids, and it is not necessarily necessary to take them directly from food. These amino acids include glycine 、 alanine 、 serine 、 Aspartate 、 glutamate (and its amine) proline 、 Arginine 、 histidine 、 Tyrosine 、 Cystine 。 Some non essential amino acids such as Cystine and Tyrosine If the supply is sufficient, the requirement of methionine and phenylalanine in essential amino acids can also be saved.

The nutritional value of food protein depends on the type and quantity of amino acids contained, so nutrition can also be divided into Complete protein 、 Semi complete protein and Incomplete protein Three types.

1. The essential amino acids contained in complete protein are complete in variety, sufficient in quantity and appropriate in proportion, which can not only maintain the health of adults, but also promote the growth and development of children, such as casein and lactalbumin in milk, ovalbumin and ovophosphoprotein in eggs, albumin in meat Myoprotein , soybean protein in soybean, glutenin in wheat, glutenin in corn, etc.

2. Semi complete protein contains a complete range of essential amino acids, but some amino acids are insufficient in quantity and proportion, which can maintain life but cannot promote growth and development, such as glutenin in wheat.

3. Incomplete proteins contain incomplete essential amino acids, which can neither sustain life nor promote growth and development, such as corn gluten in corn, glial protein in animal connective tissue and meat skin, and legumin in pea.

Shape classification

According to the shape of protein molecules, they can be divided into three categories:

1． Globular protein The molecular shape is close to spherical, water solubility is good, and there are many kinds, which can make a variety of biological functions possible.

2． Fibrous protein The molecular shape is rod like or fibrous, most of which are insoluble in water organism Important structural components, or play a role in protecting organisms.

3． Membrane protein Generally, it is folded into a nearly spherical shape and inserted into the biofilm. Some are bound to the surface of the biofilm through non covalent bonds or covalent bonds. Most functions of biomembrane are Membrane protein Implemented.

Structure type

fibrin Fibrous protein: a major class of water-insoluble proteins, which usually contain polypeptide chains with the same secondary structure. Many fibrins are tightly bound and provide mechanical strength for a single cell or the whole organism, playing a protective or structural role.

Globulin Global protein: Compact, nearly spherical, a class of proteins containing tightly folded polypeptide chains, many of which are soluble in water. Typical globulins contain pits or fissures that can specifically identify other compounds.

Keratin (keratin): from α- screw or β- fold The conformational parallel polypeptide chains form water insoluble proteins that play a protective or structural role.

collagen Collagen: It is the most abundant protein in animal connective tissue, and it is composed of protocollagen molecules. Procollagen is a kind of protein with Helical structure Protein. Each tropocollagen molecule is formed by right-handed rotation of three special left-handed helical polypeptide chains (pitch 0.95nm, each circle contains 3.3 residues).

Bridesmaid protein Chaperone: It forms a complex with a newly synthesized polypeptide chain and helps it fold correctly into a protein with biological functional orientation. Bridesmaid proteins can prevent the formation of incorrectly folded intermediates and the incorrect aggregation of unassembled protein subunits, assist in the transmembrane transport of polypeptide chains and the assembly and disassembly of large multi subunit proteins.

myoglobin (myoglobin): It consists of a peptide chain and a hemoglobin Cobasic Binding protein It is a protein that stores oxygen in muscle. Its oxygen saturation curve is hyperbolic.

hemoglobin (hemoglobin): It is a binding protein composed of four subunits containing heme cofactor. Hemoglobin is responsible for transporting oxygen from lung to peripheral tissue, and its oxygen saturation curve is S-shaped.

According to their components, proteins can be divided into simple proteins and conjugated proteins. Some protein molecules are only composed of amino acid residues and do not contain other chemical components. These proteins are called pure proteins. Some protein molecules are composed of amino acid residues and other chemical components. This type of protein is called conjugated protein.

Proteins can be classified into active proteins and inactive proteins according to their functions. Active protein refers to all active proteins in the life process, such as enzymes, hormone proteins, etc. Inactive proteins are those that protect organisms or^[3] Supporting proteins, such as collagen, keratin, etc.

According to solubility, proteins can be classified into albumin, globulin, glutenin, gliadin, hard protein, histone, protamine, etc.

Protein denaturation (Denaturation): The destruction of the natural conformation of biological macromolecules leads to the loss of their biological activity. Proteins are exposed to light, heat, organic solvents and some Denaturant When the, secondary bond It is destroyed, leading to the destruction of the natural conformation and the loss of biological activity of the protein.

Renaturation (renaturation): Under certain conditions, denatured biological macromolecules are restored to the natural conformation with biological activity.

Allosteric effect (allosteric effect): also known as Allosteric effect It is a phenomenon that oligomeric proteins combine with ligands to change the conformation of proteins, leading to changes in the biological activity of proteins.

The structure of proteins that help cancer cells

When cancer cells proliferate rapidly, they seem to need the help of a protein called survivin. According to some researchers, survivin proteins are unexpectedly combined in the form of paired pairs - this discovery may provide a new insight into the design of anti-cancer drugs.

In order to find out what role survivin plays, Joseph Noel, a structural biologist from California, USA, and his colleagues took the lead in carefully observing its three-dimensional structure. They irradiated the protein crystal with X-ray and measured the deflection angle of the X-ray, which allows researchers to calculate the position of each atom in the protein. The results they obtained indicate that survivin protein forms a knot, which is not formed by other apoptosis inhibitors. The researchers reported in the journal Nature Structural Biology published in July that part of the survivin molecule was unexpectedly linked with the corresponding part of another survivin molecule, forming a protein pair called dimer. Researchers speculate that dimers of these survivin proteins may maintain key molecular structures during cell division. If the protein has to be paired to function, then separating them with a small molecule might be able to fight cancer.

Guy Salvesen, a biochemist, said that mastering the structure of survivin protein "does not clarify the mystery of how it prevents cell suicide". But he said that the fact that these proteins are paired is really surprising. "It is almost difficult for you to find unimportant dimerization regions". He also agreed that the interface between the two proteins would be a good target for anti-cancer drugs to focus on.

source

The main sources of protein are meat, eggs, milk and legumes. Generally speaking, the protein from animals has high quality and contains sufficient essential amino acids. There are about 8 kinds of essential amino acids, which cannot be synthesized by the body itself and must be ingested from food. If there is an insufficient amount of essential amino acids in the body, it is impossible to synthesize sufficient protein for use by various tissues of the body. Other excess proteins will also be metabolized by the body and wasted, so it is important to ensure adequate intake of essential amino acids. Vegetarian proteins usually have insufficient content of 1-2 essential amino acids, so vegetarians need to take a variety of foods and get enough essential amino acids from various combinations. A piece of cooked meat about the size of a poker card contains about 30-35 grams of protein, a large cup of milk about 8-10 grams, and a half cup of various beans about 6-8 grams. So eating a piece of meat the size of a poker card, drinking two large cups of milk, some beans, and a small amount of vegetables, fruits and rice a day can get about 60-70 grams of protein, enough for a long-distance runner weighing 60 kg. If your demand is large, you can drink an extra glass of milk or eat more meat to get sufficient protein.

Consumption

Announce

edit

Protein food is an important nutrient for the human body, and ensuring the supply of high-quality protein is an important issue related to health. The selection of economical and nutritious protein is a topic of general concern.

First of all, we should ensure that there is enough protein food in quantity and quality. According to the research of nutritionists, an adult needs to update more than 300g of protein every day through metabolism, of which 3/4 comes from amino acids generated in the metabolism of the body. The reuse of these amino acids greatly reduces the amount of protein to be supplied. Generally speaking, an adult takes 60g~80g protein every day, which can basically meet the needs.

Secondly, a reasonable combination of various foods is an economical and effective way to improve the nutritional value of protein. One third of the protein eaten every day should preferably come from animal protein and two thirds from plant protein. The Chinese people have the habit of eating mixed food. They mix several proteins with low nutritional value. The amino acids in them complement each other, which can significantly improve the nutritional value. For example, cereal proteins contain less lysine and more methionine. Legume proteins contain more lysine and less methionine. When these two types of proteins are mixed, essential amino acids complement each other, close to human needs, and the nutritional value is greatly improved.

Third, each meal should contain a certain amount of protein. The human body has not set up a storage warehouse for protein. If you eat too much protein at one time, it will inevitably cause waste. On the contrary, when the protein in the food is insufficient, adolescents will suffer from stunting, and adults will feel weak, lose weight, and weaken their resistance to disease.

Fourth, protein consumption should be based on sufficient heat supply. If the heat supply is insufficient, the body will consume the protein in food as energy. Each gram of protein provides 18 kJ of heat when oxidized in the body, which is equivalent to glucose. It is a waste to use protein as energy.

Protein intake may be excessive, and the amount of protein needed to maintain health varies from person to person.

The average healthy adult male or female needs about 0.8 grams of protein per kilogram (2.2 pounds) of weight.

Related research

Announce

edit

Extended life

According to foreign media reports, a pioneering study may become the key to longevity and health of the elderly. American researchers found a protein called SIRT1. It can not only prolong the life span of mice, but also delay the age of onset related to health. In addition, it can improve the overall health of mice, reduce cholesterol levels, and even prevent diabetes. The researchers said that although the study was conducted on mice, it will eventually be applied to humans one day.

The research team led by Dr. Rafael DeCabo of the National Institute of Aging, National Institutes of Health, examined the impact of the small molecule SIRT1720 that activates SIRT1 on the health and life span of mice. "We have verified for the first time that the artificial SIRT1 activator not only prolongs the life span of mice fed on standard food, but also improves their health span. This indicates that we may develop molecules to reduce the burden of age-related metabolic diseases and chronic diseases." These researchers also found that, SRT1720 The average life span of mice was prolonged by 8.8%.

SRT1720 supplement also reduced body weight and body fat percentage, and improved muscle function and motor coordination ability of mice throughout their lives.

Scientists found that SRT1720 supplements reduce the level of total cholesterol and low-density lipoprotein cholesterol that helps fight heart disease, and improve insulin sensitivity that may help prevent diabetes.

It is known to scientists that SIRT1 and its sister protein SIRT2 play an important role in the metabolism of a large number of species. They are also involved in DNA repair and gene regulation, which may help prevent diabetes, heart disease and cancer. Mice were given this supplement and a standard diet at 6 months of age and other life stages. But experts warn that this research is still in a very early stage, and no relevant experiments have been conducted on people.

Related disciplines

Announce

edit

one thousand nine hundred and eighty-two American S. B. Prusiner discovered the protein factor Prion, which updated the concept of medical infection and won the Nobel Prize in Physiology and Medicine in 1997.

One of the most amazing discoveries in the 20th century is that the active and inactive states of many proteins can be transformed into each other. Under a precisely controlled solution condition (such as removing the chemical substances that cause inactivation through dialysis), the inactive proteins can be transformed into the active form. How to restore proteins to their active state is a major research field of biochemistry, which is called protein folding.

Protein synthesis is to transcribe the information hidden in DNA into mRNA through the role of enzymes in the cell, and then transport the corresponding amino acids into the ribosome according to the principle of codon anti codon pairing by tRNA, and arrange them in sequence according to the coding of mRNA to form polypeptide chains, and then fold and twist them into proteins. Protein is the basic macromolecule of life. Think of it as a living brick.

Through genetic engineering, researchers can change the sequence and thereby change the structure, target substances, regulatory sensitivity and other properties of proteins. Gene sequences of different proteins can be spliced together to produce "absurd" proteins with two protein properties. This fusion form has become a major tool for cell biologists to change or detect cell functions. In addition, another attempt in the field of protein research is to create a protein with new properties or functions, which is called Protein Engineering 。

Food content

Announce

edit

protein

Foods with more protein include: livestock milk, such as milk, goat milk, horse milk, etc; Livestock meat, such as cattle, sheep, pork, etc; Poultry meat, such as chicken, duck, goose, quail, etc; Eggs, such as eggs, duck eggs, quail eggs, fish, shrimp, crabs, etc; There are also soybeans, including soybeans, big green beans and black beans. Among them, soybeans have the highest nutritional value and are a high-quality source of protein in infant food; In addition, the protein content of dried fruits such as sesame, melon seeds, walnuts, almonds and pine nuts is high. Because the content and type of amino acids in various foods are different, and the content of other nutrients (fat, sugar, minerals, vitamins, etc.

protein

Protein food is expensive. Parents can mix several cheap foods together to improve the utilization rate of protein in the body. For example, the biological value of corn alone is 60%, that of wheat is 67%, and that of soybeans is 64%. If these three foods are mixed in proportion, the utilization rate of protein can reach 77%. It is a kind of biological macromolecule which mainly consists of amino acids and is ubiquitous in organisms. It and nucleic acid are the most basic substances of organisms, and bear various extremely important functions in the process of life activities. The basic structural unit of protein is amino acid. There are 20 kinds of amino acids in protein. Amino acids are linked together by peptide bonds to form peptide chains.

A Brief History of H. Bracono's Discovery in 1820 glycine And leucine, which was initially identified as the amino acid component of protein, and later other amino acids were found in succession. By the end of the 19th century, it was clear that proteins were mainly composed of a rather simple class of organic molecules - amino acids. In 1902, E. Fischer and F. Hofmeister independently clarified that the chemical bond connecting amino acids in protein molecules is peptide bond; In 1907, E. Fischer successfully linked 18 amino acids with chemical methods to synthesize polypeptides for the first time, thus establishing the polypeptide theory as the basis of protein chemical structure. The knowledge of precise three-dimensional structure of protein mainly comes from the knowledge of protein crystal X-ray diffraction analysis , 1960 J C. The crystal structure of myoglobin was determined by X-ray diffraction analysis technology for the first time in Kendrew, which is the first protein with three-dimensional structure clarified. In 1965, Chinese scientists completely synthesized crystalline bovine insulin by chemical synthesis, and realized the artificial synthesis of protein for the first time; From 1969 to 1973, the resolution of 2.5 and 1.8 angstroms were measured successively Porcine insulin This is the first three-dimensional structure of protein clarified in China.

activity

After the protein molecule is affected by some external physical and chemical factors, although the peptide chain of the molecule does not break, its natural three-dimensional structure is changed and destroyed, resulting in the loss of biological activity of the protein and other changes in physical and chemical properties. This phenomenon is called protein denaturation. As early as 1931, Chinese biochemist Wu Xian put forward the correct theory of denaturation for the first time. The main factors causing protein denaturation are: ① temperature. ② PH value. ③ Organic solvent. ④ Urea and guanidine hydrochloride. This is the most widely used protein denaturing reagent. ⑤ Detergents and aromatic compounds.

Protein denaturation is often accompanied by the following phenomena: ① loss of biological activity. This is the main feature of protein denaturation. ② Changes in chemical properties. ③ Changes in physical properties. After the denaturation factor is removed, the denatured protein molecule can return to the natural conformation before denaturation, which is called protein renaturation. Protein renaturation includes complete renaturation, basic renaturation or partial renaturation. Only a few proteins can be completely refolded after severe denaturation. The study of protein denaturation and renaturation is very important for understanding the folding process of protein molecules in vivo and in vitro. Through the study of protein denaturation and renaturation, we confirmed the spontaneity of protein folding, and confirmed that the characteristic three-dimensional structure of protein molecule only depends on its amino acid sequence. When the active protein molecule is just synthesized in the organism, it often does not show activity, that is, it does not have the specific biological function of this protein. In order to make protein present its biological activity, a very common phenomenon is that the peptide chain of protein molecule must be broken in a specific way in some biochemical processes. Protein activation is a kind of biological regulation, and this kind of phenomenon widely exists in various important life activities.

Many proteins are composed of subunits. When these proteins complete their biological functions, the regulation of efficiency and reaction speed largely depends on the relationship between subunits. It is quite common that subunits participate in the regulation of protein function, especially in the regulation of enzyme catalytic function. Some enzymes have allosteric sites that do not overlap with the active site. The combination of allosteric sites and allosteric ligands will cause changes in the three-dimensional structure of the enzyme molecule, which will lead to changes in the three-dimensional structure of the active site. Such changes may enhance or inactivate the catalytic ability of the enzyme. Such enzymes are called allosteric enzymes. Known Allosteric enzyme There are two or more subunits in structure.

function

Protein has many functions in organism.

Catalytic function: The protein with catalytic function is called enzyme. All chemical reactions of organism metabolism are catalyzed by enzyme.

Motor function: From the lowest bacterial flagellum to the muscle contraction of higher animals, it is realized through protein. Muscle relaxation and contraction are mainly completed by the sliding of thick filaments with myosin as the main component and fine filaments with actin as the main component.

Transport function: In the process of life activities, many small molecules and ions are transported by various specific proteins. For example, plasma albumin transports small molecules in the blood, and hemoglobin in red blood cells transports oxygen and carbon dioxide.

Mechanical support and protection function: the tissues with mechanical support function such as bone, connective tissue and hair, skin, nails and other tissues with covering protection function of higher animals are mainly composed of collagen 、 Keratin , elastin, etc.

Immune and defense functions: In order to maintain their own survival, organisms have a variety of defense means, many of which are executed by proteins. For example, antibodies are a kind of highly specific proteins, which can recognize and combine foreign substances that invade organisms, such as foreign proteins, viruses and bacteria, and cancel their harmful effects.

Regulatory function: Polypeptides and protein hormones play an extremely important role in maintaining normal life activities of organisms, regulating metabolic function, controlling growth, development and differentiation, regulating reproductive function and species continuation. In addition, there are proteins that receive and transmit regulatory information, such as receptor proteins of various hormones.

development

As biological macromolecules that play an important role in life activities, proteins are closely related to all major research topics that reveal the mysteries of life. Protein is the main food component of human and other animals. High protein diet is one of the important signs of improving people's living standards. Many pure protein preparations are also effective drugs, such as insulin, human gamma globulin and some enzyme preparations. In terms of clinical tests, the determination of the activity of related enzymes and the changes of some proteins can be used as indicators for clinical diagnosis of some diseases, for example, the identification of lactate dehydrogenase isoenzyme can be used as an indicator of myocardial infarction, and the increase of alpha fetoprotein can be used as an indicator of early liver cancer. In industrial production, some proteins are important raw materials for food industry and light industry. For example, wool and silk are proteins, and leather is treated collagen. The application of various enzymes in leather making, pharmaceutical, silk reeling and other industrial sectors can improve production efficiency and product quality. The importance of protein in agriculture, animal husbandry and aquaculture is also obvious.

The protein can be used as a reagent to screen compounds or salts thereof that can promote or inhibit the activity of the protein of the invention. Furthermore, the compound or salt thereof and the neutralizing antibody inhibiting the protein activity of the invention can be used as a drug for treating or preventing bronchial asthma, chronic obstructive pulmonary disease, etc.

Protein plays a very important role in the process of life activities of cells and organisms. The structure and shape of organisms are related to proteins. Proteins also participate in the regulation of gene expression, as well as redox, electron transmission, neurotransmission, learning and memory and other life activities in cells. Enzymes that catalyze various biochemical reactions in cells and organisms are mainly proteins. Many important hormones, such as insulin and thymus hormone, are also proteins. In addition, a variety of proteins, such as those in plant seeds (beans, peanuts, wheat, etc.), animal proteins, cheese, etc., are used for biological nutrition growth. Some proteins, such as snake venom and bee venom, are weapons for animals to attack and defend.

Protein accounts for 20% of the human body, accounting for the largest proportion of the body. Bile, with the exception of urine, is made of protein. Only when protein is sufficient can metabolism be normal. Like building a house, the main raw material for building the body is protein.

1. Protein is the basic material for constructing new tissues and the raw material for enzyme and hormone synthesis; Maintain potassium and sodium balance; Eliminate edema.

2. It is the composition of synthetic antibody: white blood cells, T lymphocytes, interferon, etc., to improve immunity.

3. Provide some energy.

4. It can lower blood pressure, buffer anemia, and is the carrier of red blood cells.

5. Form human collagen. Collagen is found in the vitreous and rhodopsin of the eye.

7. The power source of brain cell division is protein; Cerebrospinal fluid is protein synthesis; Memory decline

8. Sexual dysfunction

9. Liver: hematopoietic function; Synthetic hormone, enzyme; Detoxification. Lack of protein, unhealthy liver cells. With a good liver, people's health is guaranteed.

10. Heart --- pump organ. Lack of protein will lead to cold hands and feet; Hypoxia; Myocardial hypoxia causes heart failure - death.

11. Spleen and stomach: Digest food every day. Digestive enzyme is protein synthesis. Lack of stomach power will lead to indigestion and belching. Gastric ulcer, gastritis; If you have too much stomach acid and stimulate the ulcer surface, you will feel pain. Protein has the only function of repairing and regenerating cells. There are ligaments on the digestive wall. Lack of protein will cause relaxation, viscera prolapse, and uterus prolapse.

12. Limbs: People grow old first, and muscle atrophy due to lack of protein; The toughness of bone is reduced and it is easy to fracture

13. Antibodies will decrease, easy to catch cold and have fever.

Main research

Announce

edit

history

In the 18th century, Antoine Fourcroy and other researchers found that proteins are a unique class of biological molecules. They found that treating some molecules with acid can make them coagulate or flocculate. At that time, they noticed examples from egg white, blood, serum albumin, cellulose and protein in wheat gluten. Gerhardus Johannes Mulder, a Dutch chemist, conducted element analysis on general proteins and found that almost all proteins have the same experimental formula. The use of the term "protein" to describe such molecules was proposed by Yongs Bezelius, a collaborator of Mulder, in 1838. Mulder then identified the degradation product of the protein and found that it contained leucine as an amino acid, and obtained its molecular weight (very close to the correct value) of 131 Da.

For early biochemists, the difficulty of studying proteins was that it was difficult to purify a large number of proteins for research. Therefore, early research focused on proteins that can be easily purified, such as proteins in blood, egg white, various toxins, and digestive and metabolic enzymes (obtained from slaughterhouses). In the late 1950s, Armour Hot Dog Co. purified ribonuclease A from one kilogram of pure bovine pancreas and provided it to scientists all over the world for free. Scientists can buy more and more pure proteins from biological companies.

The famous chemist Linus Pauling successfully predicted the secondary structure of regular proteins based on hydrogen bonds, which was first proposed by William Asterbury in 1933. Later, Walter Kauzman proposed that protein folding is mediated by hydrophobic interaction on the basis of summarizing his research achievements on denaturation and previous research work of Kaj Linderstrom Lang. In 1949, Frederick Sanger correctly determined the amino acid sequence of insulin for the first time, and verified that protein is a linear (without bifurcation or other forms) polymer formed by amino acids. The protein structure with atomic resolution was first analyzed by X-ray crystallography in the 1960s; In the 1980s, NMR was also used to analyze the structure of proteins, and cryoelectron microscopy was widely used to analyze the structure of supramolecular complexes. As of February 2008, the three-dimensional structure coordinates of proteins and their related complexes with nearly 50000 atomic resolutions have been stored in the protein database.

research method

Proteins are a class of biomolecules that have been studied most, and their research includes "in vivo" and "in vitro". In vitro studies are mostly applied to purified proteins, which are placed in a controllable environment in order to obtain their functional information; For example, studies related to enzyme kinetics can reveal the chemical mechanism of enzyme catalyzed reaction and the relative affinity with different substrate molecules. In vivo research experiments focus on the active role of protein in cells or the whole tissue, so as to understand the place where protein functions and the corresponding regulatory mechanism.

Anticancer effect

When cancer cells proliferate rapidly, they need the help of a protein called survivin. This protein is composed of Apoptosis inhibitor gene Survivin Coded synthesis is abundant in cancer cells, but almost absent in normal cells. This dependence of cancer cells on survivin protein makes survivin naturally become the target of new anti-cancer drugs, but there are still some unsolved mysteries on how to deal with survivin protein.

Survivin proteins belong to a class of proteins that prevent cell self destruction (i.e. apoptosis). These proteins mainly inhibit the action of apoptosis enzymes (caspases) to prevent them from sending cells to suicide. Previously, no scientists had observed the interaction between survivin protein and apoptotic enzymes. There are also other indications that survivin protein plays a different role - helping to pull cells apart after cell division.

Biochemist Guy Salvesen has mastered the structure of survivin protein "without clarifying the mystery of how it can prevent cell suicide". The fact that these proteins are paired is indeed surprising, and it is almost difficult to find unimportant dimerization regions. The contact surface of the two proteins will be a good target for anti-cancer drugs to focus on.

Omics

Mentioned before 1996 Proteomics (Proteomics), I'm afraid that very few people know about it, and some people are skeptical about one or two things. However, Science magazine in 2001 has listed proteomics as six major studies hotspot First, its "heat" is second only to stem cell research. Proteomics has attracted great attention.

1. Significance and background of proteomics research

along with human genome project Life science research has entered post-genomic era 。 In this era, the main research objects of life science are Functional genomics , including structural genome research and proteome research. Although the genomes of many species have been sequenced, the function of more than half of the genes in these genomes is usually unknown. The strategies used in functional genomics, such as gene chip and serial analysis of gene expression (SAGE), are all considered from the perspective of mRNA in cells, on the premise that the level of mRNA in cells reflects the level of protein expression. But this is not the case. From DNA, mRNA and protein, there are three levels of regulation, namely Transcriptional regulation (Translational control), translational control, post translational control. From the perspective of mRNA, in fact, it only includes transcriptional regulation, which does not fully represent the level of protein expression. Experiments have also proved that the correlation between mRNA abundance and protein abundance in tissues is not good, especially for low abundance proteins. More importantly, the complex post-translational modifications of proteins, subcellular localization or migration of proteins, and protein-protein interactions can hardly be judged from the mRNA level. Undoubtedly, protein is the executor of physiological functions and the direct embodiment of life phenomena. The study of protein structure and function will directly clarify the change mechanism of life under physiological or pathological conditions. The existence form and activity law of protein itself, such as post-translational modification, interaction between proteins and protein conformation, still rely on the direct research on proteins to solve the problem. Although the variability and diversity of proteins and other special properties make protein research technology much more complex and difficult than nucleic acid technology, it is these characteristics that participate in and affect the entire life process.^[5]

2. Strategy and scope of proteomics research

Once proteomics emerged, there were two research strategies. One can be called“ Depletion method ”That is, using high-throughput proteome research technology to analyze as many or nearly all proteins in the organism as possible. This view views proteomics from a large-scale and systematic perspective, which is more consistent with the essence of proteomics. However, as protein expression changes with time and space, it is difficult to analyze all proteins in the organism. Another strategy can be called "functional approach", that is, to study the changes of cell protein composition in different periods, such as protein differential expression The main goal is to find different protein types. This view is more inclined to take proteomics as a means and method to study life phenomena.^[5]

The research scope of early proteomics mainly refers to the expression profile of proteins. With the development of the discipline, the research scope of proteomics is also constantly improving and expanding. The study of post-translational modification of proteins has become an important part and a great challenge in proteome research. The study of protein-protein interaction has also been included in the field of proteomics. The analysis of protein high-level structure is the traditional structural biology. Although some people try to bring it into the scope of proteomics research, it is still unique.^[5]

3. Proteomics research technology

It can be said that the development of proteomics is both driven and limited by technology. The success of proteomics research largely depends on the level of its technical methods. Protein research technology is far more complex and difficult than gene technology. Not only are the types of amino acid residues far more than those of nucleotide residues (20/4), but also proteins have complex post-translational modifications, such as phosphorylation and glycosylation, which bring many difficulties to the separation and analysis of proteins. In addition, it is not easy to amplify and purify proteins in vitro through expression vectors, so it is difficult to prepare a large number of proteins. The rise of proteomics has brought new demands and challenges to technology. Proteomic research is essentially a large-scale parallel separation and analysis of proteins at the cellular level, often dealing with thousands of proteins at the same time. Therefore, the development of high-throughput, high sensitivity and high accuracy research technology platform is the main task of proteomics research for a long time. The technical basis and development trend of the international proteome research technology platform are as follows:

3.2 Sample separation and analysis in proteome research

It is an effective method to distinguish different proteins by two-dimensional gel electrophoresis using their isoelectric points and molecular weights. It plays a key role in proteome separation technology. How to improve the separation capacity, sensitivity and resolution of two-dimensional gel electrophoresis, as well as the accurate detection of protein differential expression, are the key issues in the development of two-dimensional gel electrophoresis technology. The main trends abroad are the use of narrow pH gradient gel separation in the first dimensional electrophoresis and the development of highly sensitive protein staining techniques combined with two-dimensional gel electrophoresis, such as new fluorescent staining techniques.

Mass spectrometry is the fastest growing, most dynamic and potential technology in proteome research. It judges the type of protein by measuring the quality of protein. At present, the core technology of proteome research is two-dimensional gel electrophoresis mass spectrometry, that is, proteins are separated by two-dimensional gel electrophoresis, and then identified one by one by mass spectrometry. For protein identification, high throughput, high sensitivity and high precision are three key indicators. The general mass spectrometry technology is difficult to integrate the three, and the developed mass spectrometry technology can meet the above three requirements at the same time, so as to achieve accurate and large-scale identification of proteins.^[5]

The nitrogen content of protein is relatively constant, with an average of about 16%.

Relationship with height

It is reported that during the Second World War, the supply of animal food in Japan was insufficient, and each person only supplied 2 kg of meat, 12.5 kg of milk and dairy products, and 2.5 kg of eggs every year. At that time, the average height of 12 year old students was only 137.8 cm. After the war, Japan's economy developed rapidly, people's lives improved, and animal food increased. Each person consumed 13 kg of meat, 25 kg of milk and dairy products, and 15 kg of eggs every year. According to the 1970 survey, the height of 12 year olds (children's food) has reached 147.1 cm, with an average increase of 9.3 cm. From this example, we can see the effect of protein food (protein food) on the increase of children (children's food).

Protein is the main compound that constitutes all life, the material basis and the first element of life, and occupies the primary position in nutrients. Protein is indispensable for the growth of children and infants. Human bones and other tissues are composed of proteins. In all chemical reactions of metabolism in the body, the catalysis of enzymes is indispensable, and all enzymes are composed of proteins. All kinds of hormones that play a role in the growth of teenagers are also proteins and their derivatives. In addition, osteocalcin, osteocalcin alkaline phosphatase Human bone specific growth factor and other substances are also composed of proteins. Therefore, protein is the most important compound in human growth and development, and an important raw material for growth.

The fat soluble vitamins (vitamin food), iron (iron food), calcium, phosphorus and other inorganic salts and some trace elements (trace element food) necessary for the growth and development of infants (infant food) and children can also be obtained in protein food. Therefore, some children and adolescents only like to eat vegetarian food (vegetarian food), and are afraid of eating chicken, fish, meat, eggs and other meat dishes, or only reluctantly eat a little under the supervision of their parents. This practice is not advisable, and will inevitably lead to a lack of protein and affect their height.

The correct dietary principle is that the food should be diversified, the thickness should be matched, and the food, beans and vegetables should be given priority to. The amount of meat, fish, eggs and milk should be appropriately increased to supplement adequate nutrition for physical development, ensure the raw materials for increasing height, and promote height.

Supplementary instructions

Announce

edit

The protein food source of protein can be divided into two categories: plant protein and animal protein. In plant protein, cereal contains about 10% protein, which is not high, but it is still the main source of dietary protein because it is the staple food of people. Legumes are rich in protein, especially the protein content of soybeans is up to 36%~40%. The amino acid composition is also relatively reasonable, and the utilization rate in the body is high. It is a very good source of protein in plant protein.

Eggs contain 11%~14% protein, which is an important source of high-quality protein. Milk (milk) generally contains 3.0%~3.5% protein, which is the best source of protein for infants. Protein is composed of amino acids. Among the 22 kinds of amino acids necessary for the human body, 9 kinds of amino acids (amino acid food) cannot be synthesized by the human body or are insufficient in synthesis, and must be obtained through diet.

Meat includes the muscles of poultry, livestock and fish. Fresh muscle contains 15%~22% protein. The nutritional value of muscle protein is superior to plant protein, and it is an important source of human protein.

The main sources of protein are animal protein and plant protein. Generally speaking, the nutritional value of animal protein is higher than that of plant protein. Calculated by the protein content per 500g, the foods rich in protein include:

① Meat: 84.5g pork, 100.5g beef, 100.5g pig liver;

② Eggs: 63.5g eggs, 63g duck eggs;

③ Fish and shrimp: carp 88 g, Grass Carp 83g, 80g shrimp;

④ Rice and flour: 60.5g wheat flour, 50g barley, 42.5g corn;

⑤ Beans: Mung bean 11g, 108.5g red bean, 249g black bean;

⑥ Vegetables: 70g day lily, 41g kelp. The nutrition of soybean protein is good, and both soybean protein and animal protein are high-quality proteins.

Calculate demand

The amount of protein required will vary due to various factors such as health status, age and weight. People who are taller or younger need more protein.

The following figure is the index of protein required by people of different ages:

Protein index required by people of different ages
Age/year	1~3	4~6	7~10	11~14	15~18	Above 19
index	one point eight zero	one point four nine	one point two one	zero point nine nine	zero point eight eight	zero point seven nine^[2]

The calculation method is:

First find out your age index; Then multiply this index by your own weight (kg); The answer is the grams of protein you need in a day.

For example, the weight is 50 kg, the age is 33 years old, and the index is 0.79.

0.79 × 50=39.5 g. This is the amount of protein needed for a day.

The minimum protein requirement in an average day is about 45g, that is, about 15g for a meal. Note that you must take adequate protein for breakfast.

It is applicable to all people who need protein supplement. Pregnant women and breast-feeding women, urban white-collar workers with high work pressure, often staying up late to work, elderly parents, children in growth and development, surgical rehabilitation, hypertension.

Supplement after delivery

about childbirth Three points should be paid attention to in the intake of post protein:

First, the intake of protein should be sufficient, because new mothers need to take in enough protein for lactation;

Second, protein should be of high quality. Generally speaking, fish and shrimp proteins are better than meat, and white meat is better than red meat. Try not to eat meat that may be artificially fed with hormones, but natural food;

Third, protein intake should be balanced, and you should not choose only one kind of food to eat.

A few people do not have enough milk, and the feeding is slow. To help feeding, they can drink some soup with Chinese medicine ingredients. This helps the mother's body to recover and recuperate (uterine contraction, lochia discharge), and milk is smooth, and can supplement nutrition.

Fitness crowd supplement

During the period of fitness exercise, the demand for protein of the human body is much stronger than that of other stages. Grain proteins contain less lysine. If they are eaten together with soybeans, meat, eggs and other foods that contain more lysine, they will improve the nutritional value of each other. For another example, the methionine content in soybeans is very low, while that in corn is very high. If they are combined, they will complement each other and improve the nutritional value.

Through the above examples, we can adjust our previous diet structure during the fitness exercise period, achieve food diversification, balance the allocation of coarse grains and fine grains, reasonably distribute animal protein to each meal, and take an appropriate amount of bean products, which can improve the nutritional value of each meal. In this case, the final result of fitness exercise is that the fitness effect is significantly improved.

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001