Oneamino acidThe amino group ofPeptide bond。The molecule of amino acid is the smallest, the protein is the largest, and two or moreAmino acid dehydration condensationSeveral peptide bonds are formed to form a peptide chain, and multiple peptide chains are folded to form a protein molecule.Proteins are sometimes referred to as "peptides".Dipeptide (Dipeptide for short) is a protein segment composed of two amino acids.
IIamideone of.It consists of two or more amino acids passing through one amino acidaminoIt is combined with the carboxyl group of another amino acid.One amino acid cannot be called peptide, nor can it be synthesized. It must be two or more amino acidsPeptide bondConnected compounds.The compound of two amino acids linked by peptide bond is calledDipeptide；The compound of three amino acids linked by peptide bond is called tripeptide, and so on, the compound of thirty-four amino acids linked by peptide bond is called thirty-four peptide.
Peptide is a chain like amino acid polymer
3、 It involves multiple cell functions in the organismbiological activitySubstance.Hundreds of peptides have been found in the organism, and they are indispensable participants for the organism to complete various complex physiological activities.All cells can synthesizepolypeptideThe functional activities of substances are also regulated by polypeptides.It involves hormones, nerves, cell growth and reproduction. Its importance lies in regulating various system organs and cells in the body.The physiological and pharmacological effects of enzymatic peptides are mainly to activate the relevant enzymes in the body, promote the permeability of the intermediate metabolic membrane, or affect specific protein synthesis by controlling DNA transcription or translation, and ultimately produce specific physiological effects or play their pharmacological roles.Peptides are better than amino acids. First, they absorb faster than amino acids;Second, it is absorbed by the body in a complete form;The third is active absorption (amino acid is passive absorption);Fourth, low consumption. Compared with amino acids, peptide absorption has the characteristics of low consumption or no consumption of energy. After being absorbed through the duodenum, peptide directly enters the blood circulation to deliver its own energy and nutrition to all parts of the body;Fifth, peptide absorption is unsaturated compared with amino acid;Sixthly, there are only 20 kinds of amino acids with countable functions, while peptides can synthesize hundreds of kinds with amino acids as substrates.Peptides belong to degraded small molecule collagen, containing amino acid groups, and belong to raw material products.Peptide is also an original component in human body, which is a chain structure formed by amino acids.The protein we are familiar with is a polypeptide chain.Different peptides are formed due to different components and sequences of amino acids.Compounds connected by two amino acids with peptide bonds are called“Dipeptide”By analogy, compounds composed of 9 amino acids are called "nine peptides", and peptides composed of multiple amino acids (generally 50 or 100) are calledpolypeptideThe amino acid units that make up the polypeptide are calledAmino acid residue。The peptide bond connects the amino acid with its head and tail.[1]
Type of peptide
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Peptides, polypeptides, active peptides and large peptides
Peptides are those with molecular weight between 50 and 5000.Large peptides are those with molecular weight between 5000 and 10000.The molecular weight range between 50 and 2000 is calledSmall peptide、OligopeptideOligopeptides, also known as small molecule active peptides.Biologists refer to peptides as "amino acid chains", and collectively refer to small molecular active peptides as“Bioactive peptide”。The common ones areDipeptide（Dipeptide），Tripeptide(Tripeptide), even polypeptide, etc., while 2~10 peptides belong to Oligo peptide, and 10~50 peptides belong to Oligo peptidepolypeptideGenerally, those with less than 10 peptides are more medically and commercially practical.[1]
Preparation method
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There are many traditional methods to obtain peptides.Traditional methods mainly include: microbial fermentation, acid method, alkali method, electric method, artificial grafting method, gene expression method, enzymolysis method, etc.
·Microbial fermentationLaw:The production technology of microbial fermentation method is mainly to transform macromolecular globulin into small molecular peptide through modern microbial fermentation technology. Peptides with different amino acid sequences and molecular weights can be produced by controlling microbial metabolism and fermentation conditions.During fermentationfree amino acid It will not produce feedback inhibition on microbial metabolism if it is re absorbed and utilized by microorganisms.Through microbial metabolism, amino acids and small peptides are grafted and rearranged, and some peptide groups are modified and recombined.For example, soybean peptides produced from soybean meal through microbial fermentation have changedsoybean protein The intrinsic amino acid sequence modifies theHydrophobic amino acidAt the end, the soybean peptide has no bitter taste and higher activity, and gives some biological activity functions to the soybean peptide. It belongs to the high-tech range of bioengineering with high scientific and technological content, and can be used in food industry, fermentation industry, feed industry, pharmaceutical industry, cosmetics industry, plant nutrition promoter and other industries.It has a very wide range of uses and a very broad prospect of development and application.
·Acid method:The method of using chemical strong acid to catalyze protein to obtain peptide is called acid method. This method has large investment, large land occupation, complex process, large pollution, difficult to control molecular weight, chemical residues in the product, difficult to form functions, and difficult to achieve industrial production. It still stays in the laboratory until now.
·Alkali method:The method of using chemical strong base to catalyze protein is called alkali method, which has the same result as acid method.
·Electrical method:The method of electrolyzing protein is called electric method, which has obvious advantages, low production cost and good taste compared with enzymatic hydrolysis.
·Artificial graftingIt means that amino acids produced by fine chemical industry are selectively grafted. This method is basically operated by machines. The production is large, the peptides produced are inactive, and their physiological functions are not obvious.
·gene expressionLaw:The method of isolation and extraction from animal blood or tissue is generally referred to as gene expression method. This method is mainly used to research and produce "peptide drugs". Its representative products are:Thymosin、Thymopentin、interferon、Interleukin-1、Interleukin-11, interleukin-111, human serum albuminimmunoglobulin、Gamma globulinTumor cell necrosis factor, etc.
·Enzymatic method:The method of using biological enzyme to catalyze protein is called enzymatic method.Enzymatic method has made breakthrough and innovation on the basis of traditional method, which meets the requirements of low-carbon economy and green environmental protection.Enzymatic method is to use biological enzyme to catalyze protein to obtain polypeptide, namelyProtein degradation, synthetic peptide.Compared with acid method, alkali method and electric method, enzymatic method is mild and environmentally friendly.The production process is simple, less investment, quick effect, and suitable for industrial production.Peptides obtained by enzymatic method have easy control of molecular weight, green properties of the product itself, no bitterness and small molecular weight (mostly below 1000). These small molecular peptides do not need to be digested and absorbed directly. They have power, carrier, transport, transmitter and nutrition functions, especially they have extremely strong activity and diversity, that is, important biological functions.[1]
·Hydrolysis
Peptides can beDietary protein(Dictionary protein) can be obtained by chemical hydrolysis or manual method.It is composed of two or more amino acids (Amino acids) and plays an important role in the regulation of cell physiology and metabolic function.[1]
Application of peptides
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Mainly divided into medical categoryPeptide drugs，Peptide antibiotics，vaccine, agricultural antimicrobial peptides, feed peptides, cosmetics for daily use, soybean peptides for food, corn peptides, yeast peptides, sea cucumber peptides.
From the functional point of view, it can be divided into antihypertensive peptide, antioxidant peptide, cholesterol lowering peptide, opioid active peptide, high F value oligopeptide, food strong taste peptide, etc.
Active peptides are closely related to nutrition, hormone, enzyme inhibition, immune regulation, anti-bacterial, anti-virus and anti-oxidation.Peptides are generally divided into polypeptide drugs and polypeptide health products.The traditional polypeptide drugs are mainly polypeptide hormones. The development of polypeptide drugs has developed into various fields of disease prevention, especially in the following fields.[2]
Antineopeptide
The occurrence of tumor is the result of many factors, but ultimately involves the expression and regulation of oncogenes.In 2013, many tumor related genes and regulators have been found, and screening polypeptides that specifically bind to these genes and regulators has become a new hotspot in searching for anti-cancer drugs.For example, somatostatin has been used to treat endocrine tumors of digestive system;American scholars found a hexapeptide that can significantly inhibit adenocarcinoma in vivo;Swiss scientists found an octapeptide that can induce apoptosis of tumor cells.[2]
Antiviral polypeptide
The virus passes throughhost cellThe specific receptor on the cell can bind to the adsorption cell and rely on its own specific protease for protein processing and nucleic acid replication.Therefore, peptides that can bind to host cell receptors or active sites such as viral protease can be screened from peptide libraries for antiviral treatment.In 2013, Canada, Italy and other countries have screened many small peptides with anti disease toxicity from peptide libraries, and some small peptides have entered the clinical trial stage.June 2004Institute of Microbiology, Chinese Academy of SciencesIt was reported that the Institute of Microbiology, Chinese Academy of Sciences, and the Modern Virology Research Center, School of Life Sciences, Wuhan University had made significant progress in the important direction project of the CAS Knowledge Innovation Project, "Research on SARS Coronavirus Cell Fusion Mechanism and Fusion Inhibitor".Experiments have proved that the designed HR2 polypeptide can effectively inhibit the infection of SARS virus on cultured cells at several nmole concentrations. The virus infection inhibition experiment of synthetic and expressed HR1 polypeptide and the in vitro binding experiment of HR1 and HR2 have also made important progress. The polypeptide drug developed to prevent SARS virus fusion can prevent virus infection,For patients infected with the virus, it can prevent the further expansion of the virus in the body.The polypeptide medicine has dual functions of prevention and treatment.Researchers from the Cell Engineering Research Center of the Fourth Military Medical University have synthesized nine polypeptides that can effectively prevent and inhibit SARS virus from invading cells.[2]
Cytokine mimetic peptide
Utilize knowncell factorIn 2011, it became the focus of research at home and abroad to screen cytokine mimic peptides from peptide libraries based on receptors of.People have been screened abroadErythropoietin, human thrombopoietin, human growth hormone, human nerve growth factor andInterleukin-1The amino acid sequence of these simulated peptides is different from that of their corresponding cytokines, but they have cytokine activity andrelative molecular massSmall advantages.In 2013, these cytokines mimic peptides were in the pre clinical or clinical research stage.[2]
Antibacterial peptide
When insects are stimulated by the external environment, they will produce a large number of cationic polypeptides with antibacterial activity. In 2013, more than 100 antimicrobial peptides have been screened from them.In vivo and in vitro experiments have proved that many antimicrobial peptides not only have strong antibacterial and bactericidal abilities, but also can kill tumor cells.[2]
Polypeptide vaccine
Polypeptide vaccine and nucleic acid vaccine are one of the most important research areas in the field of vaccine research in 2013. In 2013, the world carried out a lot of research and development on viral polypeptide vaccine.For example, in 1999, NIH of the United States announced the clinical trial results of two kinds of HIV-I polypeptide vaccines on human beings;Foreign scholars screened a polypeptide from the outer membrane protein E2 of hepatitis C virus (HCV), which can stimulate the body to produce protective antibodies;The United States is developing multivalent antigen polypeptide vaccine for malaria;Human papillomavirus polypeptide vaccine for cervical cancer has enteredPhase II clinical trial。China has also done a lot of work in the research of multiple peptide vaccines.[2]
Diagnostic polypeptide
Peptides inDiagnostic reagentThe most important use of is as antigen to detect the antibodies of corresponding pathogenic organisms.The characteristics of polypeptide antigens are that they are more specific than natural microbial or parasitic protein antigens and easy to prepare.Antibody detection reagents assembled with polypeptide antigens in 2013 include: hepatitis A, B, C, G virus, HIVHuman cytomegalovirus、herpes simplex virus, rubella virusTreponema pallidum, cysticercosis, trypanosoma, Lyme disease, rheumatoid and other detection reagents.Most of the peptide antigens used are obtained from the analysis and screening of the corresponding pathogenic body's natural proteins, and some are new peptides obtained from the screening of peptide libraries.[2]
Research background
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Active peptides were discovered in 1920, but it was not until 1958 that the active peptides researched by Dr. Herber Boyer, an American Jewish biochemist and professor of the University of California, came out using cell recombination technology.
In 1990,Dr. Rudman formally put forward the theory of explaining the causes of human diseases and aging, and for the first time applied active polypeptides in the field of anti-aging and disease prevention.[2]
