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L-threonine

essential amino acid

L-threonine is an organic substance with the chemical formula C four H nine NO three , the molecular formula is NH two —CH(COOH)—CHOH—CH three 。

L-threonine was discovered by W. C. Ro in 1935 fibrin hydrolysis It has been proved that it is the last essential amino acid found. Its chemical name is α - amino - β - hydroxybutyric acid, and there are four kinds Stereoisomerism Only L-type has biological activity.

Chinese name: L-threonine
Foreign name: L-Threonine
(2S,3R)-2-Amino-3-hydroxybutyric acid a-Amino-β-hydroxybutyric acid
Alias: L- hydroxyl Butyrine (2S, 3R) - 2-amino-3-hydroxybutyric acid 、 L - α - amino - β - hydroxybutyric acid 、 L-isohaematomyces amino acid L-alpha-amino-beta-hydroxybutyric acid
chemical formula: C four H nine NO three
molecular weight: one hundred and nineteen point one one nine two
CAS login number: 72-19-5

EINECS login number: 200-774-1
Boiling point: 345.80 ℃
Density: 1.307 g/cm³
Flash point: 162.94 ℃
Molecular formula: NH2—CH(C00H)—CHOH—CH3
ChEBI: fifty-seven thousand nine hundred and twenty-six
MDL No: MFCD00064270EIN
RTECS No: XO8590000
BRN No: one million seven hundred and twenty-one thousand six hundred and forty-six
PubChem No: twenty-four million nine hundred thousand five hundred and forty-four

catalog

seven synthetic method
eight purpose

Calculate chemical data

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1. Reference value for drainage parameter calculation (XlogP): - 2.9

2、 hydrogen bond Number of donors: 3

3. Number of hydrogen bond receptors: 4

4. Number of rotatable chemical bonds: 2

5、 topology molecule Polar surface area （TPSA）：83.6

6. Number of heavy atoms: 8

7. Surface charge: 0

8. Complexity: 93.3

9、 Isotope atom Quantity: 0

10. Determine the number of atomic structure centers: 2

11. Number of uncertain atomic structure centers: 0

12. Determine the number of chemical bond structure centers: 0

13. Number of uncertain chemical bond structure centers: 0

14、 covalent bond Number of units: 1

Molecular structure data

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1、 Molar refractive index ：27.13

2、 Molar volume （m3/mol）：91.1

3. Isotonic specific volume (90.2K): 253.6

4、 surface tension （dyne/cm）：60.0

5、 Polarizability （10-24cm3）：10.75

Sex data

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1. Character: white crystal or crystalline powder, containing 1/2 Crystal water 。 Odorless, slightly sweet.

2. Density (g/mL, 25/4 ℃): 1.307

3. Relative steam density (g/mL, air=1): uncertain

4. Melting point (℃): 256 (dec.) (lit.)

5. Boiling point (℃, normal pressure): uncertain

6. Boiling point (℃, 5.2kPa): uncertain

7. Refractive index: - 28 ° (C=6, H2O)

eight flash point (℃): Uncertain

nine Specific rotation （°）：-28.4°（C=6，H2O）

ten Autoignition point or Pilot temperature (℃): Uncertain

eleven Vapor pressure (kPa, 25 ℃): uncertain

twelve Saturated vapor pressure (kPa, 60 ℃): uncertain

thirteen Heat of combustion (KJ/mol): Uncertain

14. Critical temperature (℃): uncertain

fifteen critical pressure (KPa): Uncertain

16. Oil and water（ Octanol /Water) partition coefficient Logarithm of: Uncertain

seventeen Upper explosive limit (%, V/V): Uncertain

eighteen Lower explosive limit (%, V/V): Uncertain

19. Solubility: soluble in water (200g/L, 25 ℃), insoluble in methanol, ethanol Ether and chloroform 。

toxicology data

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acute toxicity : Abdominal cavity of rats LD50 ：3098mg/kg；

Mutagenicity: human lymphocyte Sister chromatid exchange TEST SYSTEM：10mg/L；

Properties and stability

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1. Stable under normal temperature and pressure.

2. It exists in flue-cured tobacco leaves Burley tobacco In tobacco leaves and smoke.

Storage method

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The brown wide mouth glass bottle is sealed. Store in a cool and dry place away from light.

synthetic method

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The industrial production methods of L-threonine mainly include: ① synthesis method; ② Fermentation method; ③ There are three methods of protein hydrolysis. Fermentation is now advocated.

Method I Direct fermentation ：

1. The fermentation method is based on sugar, ammonia Homoserine (homoserine) as culture medium glutamate Micrococcus (glutaminus) and other products can be refined after fermentation to produce L- threonine 。

Breeding with glucose as raw material Auxotrophic type Concurrently in the synthesis of structural analogues Feedback suppression With inhibition, the acid production rate of L-threonine is 18 g/L, Corynebacterium glutamicum The acid production rate is 14g/L, and the rate of Saibacillus mucilaginis is 14g/L.

Glucose[ Brevibacterium flavum , Corynebacterium glutamicum, Ceibacterium mucosum, etc.] → L-threonine.^[1]

2. Use Micrococcus glutamicus or Brevibacterium 、 Corynebacterium Etc. sugar ammonia After high serine fermentation, it is refined, and the concentration of fermentation liquid can reach 5~20g/L.

3. Use Crotonic acid Or with glycine It is made from raw materials. It can also be made from glucose or starch via Escherichia coli , Brevibacterium flavum glutamate Bacillus or Corynebacterium crenatum is the product obtained by fermentation.

Method II: chemical synthesis:

Chemical synthesis threonine (L-threonine) is a mixture of four optical isomers, namely DL threonine 。 The amino acid composing the protein is L-threonine, so it is necessary to separate the threonine from the others, and then further carry out optical isomer resolution to obtain L-threonine.

Tobacco: BU, 22; FC，21； Synthesis: It can be composed of protein (such as casein ）Classics hydrolysis , refined, or Acrylic acid Methanol and Mercuric acetate synthesis.

use Copper glycine Under alkaline conditions and acetaldehyde Action, similar Aldol condensation reaction The threonine can be separated from the mixture of threonine copper and other threonine copper by decoppering according to their different stability and solubility DL threonine Finally, L-threonine was obtained. The production processes of pilot synthesis and scale-up are introduced as follows.^[1]

Small scale synthesis process:

glycine Preparation will Monochloroacetic acid 189g（2mol）、 Formaldehyde solution 2100ml (3.3mol), mix, cool to below 10 ℃, drip Concentrated ammonia water 750ml (10mol), control the dropping acceleration so that the temperature does not exceed 10 ℃. Finish adding ammonia After that, the temperature shall be kept at 30 ℃ for 4h. Vacuum concentration To 300-400ml, there is crystallization precipitation. After washing and drying, crude glycine is obtained. Add about 1.5-2 times of water to the crude glycine, heat it to make it fully soluble, and add 1% activated carbon to decolorize it; Filter the filtrate, add 2-2.5 times the volume of methanol, put it in the refrigerator overnight, filter and take the crystal threonine (L-threonine). The yield is about 60% - 68%.

Copper glycine Preparation of glycine 100g, add 7L water, heat at 60 ℃ to make it completely soluble. Then slowly add Basic copper carbonate 80g, heat preservation at 60 ℃ for 1h. while Thermal filtration Remove unreacted basic copper carbonate. Collect the filtrate and let it cool naturally to separate out blue acicular crystals (containing 1 molecule Crystal water ）, filtered and crystallized, washed and dried at 60 ℃ to obtain copper glycine in 95% - 98% yield.

threonine Copper preparation Take 52.5g of copper glycine, add 425ml of methanol and stir to dissolve it, then add 80ml of ethanol below 10 ℃, when the temperature no longer rises, add 5g of sodium hydroxide to dissolve it in 90ml of methanol solution in advance, and react at 60 ℃ for 1h. Filter the insoluble matter away while hot, collect the filtrate, add 5.5 ml of glacial acetic acid, decompress and recover methanol to dryness, add 75 ml of methanol, stir and disperse, and then cool overnight. The mixture of threonine and allothreonine copper was obtained by filtering, collecting and crystallizing, washing and drying, and the yield was 68% - 74%.

Remove copper, refine 427g of threonine copper, add 10% hydrogen oxidation Ammonia solution 6L, dissolve it completely, filter and collect filtrate 732 cation exchange resin Adsorption, 2mol/L ammonia Wash with water until Eluate yes Ninhydrin No color is displayed. Combine the eluent, concentrate the film to 1.5L, add 3L ethanol to separate and crystallize it, place it in the refrigerator overnight, filter and crystallize DL threonine Coarse products. The yield was 62% - 73.8%.

Take 42g of crude DL threonine, add 126ml of water to make it fully soluble, decolorize and filter the filtrate, add 252ml of ethanol, cool overnight, filter and crystallize to obtain refined DL threonine. The yield was 87% - 91.3%.

Split and refine, mix 810g of refined DL threonine, 90g of DL threonine and 2.88L of water, slowly stir (about 50r/min), and heat to above 95 ℃ to dissolve them all. Cool down to 40 ℃, and add 10% of the total DL threonine dosage d-threonine The product is slowly cooled to 30 ℃ (1 ℃ drops every 15min on average), crystallized D-threonine is precipitated, filtered and crystallized, and dried with 80 ℃ to obtain D-threonine. Collect the filtrate and put the same amount of D-threonine DL threonine (about 150-170g), keeping the total volume unchanged, the same operation as the resolution of D-threonine (but when the temperature is reduced to 40 ℃, the added Seed crystal Is L-threonine) to obtain L-threonine. After repeated operation, D-threonine and L-threonine can be separated.

Merge corresponding d-threonine Crude product and L-threonine crude product are refined respectively, namely Recrystallization 。 Take D and L-type respectively threonine , respectively add 4 times of water, heat at 90 ℃ to fully dissolve, decolorize with 1% activated carbon Thermal filtration Collect the filtrate, add ethanol of twice the volume to cool it, stir from time to time, precipitate and crystallize to obtain D-threonine and L-threonine fine products in 87.3% - 91.6% yields.

The content of L-threonine is more than 95%, [α] 20D-26 ° - 29 °, Paper chromatography A spot appears.^[1]

Enlarged production process:

with glycine As raw material, first with Basic copper carbonate Reaction formation Copper glycine At this time, its α - H is active. Under alkaline conditions, copper glycine reacts with acetaldehyde Similar cross aldehydes can occur condensation reaction , while generating DL threonine Copper (including Sutra Body and Red Body), then Ion exchange , decoppering and separating DL threonine from threonine, and finally inducing Crystallization method take d-threonine And L-threonine. The reaction is as follows:

The preparation of copper glycine is 500L reaction tank Medium, add 50kg glycine, 350L water, 40kg Copper sulfate basic Keep the temperature at 60 ℃ for 1h, filter out the unreacted copper salt, collect the filtrate, cool it overnight, filter out the crystal, dry it at 60 ℃, and get blue Copper glycine 。

threonine Prepare copper in a 1000L reaction tank, add 75kg of copper glycine, add 600L of methanol, stir to dissolve it, add 120L of acetaldehyde, 90L5% KOH methanol solution, stir and keep at 60 ℃ for 1h, filter the insoluble matter, add 5.5L of glacial acetic acid to the filtrate, decompress and recover methanol to dryness, add 75L of water, stir and disperse, and then stand overnight at 5 ℃, filter and crystallize, wash The mixed threonine copper of threonine and other threonine was obtained by drying.

Ion exchange , decoppering separation DL threonine Add 40kg and 10% of the above threonine copper ammonia Put 1000L into 2000L reaction tank Stir to dissolve it, filter the filtrate into 732 cation exchange column (400mm × 200mm), and then use 2mol/L ammonia water and Deionized water wash. merge Eluate , the film is concentrated to 150L, 300L ethanol is added, stirred, and cooled to 5 ℃ for crystallization overnight. Filter and crystallize, and dry at 80 ℃ to obtain crude DL threonine.

Concentrate and refine 40kg DL threonine crude product into 500L reaction tank Medium.^[1]

purpose

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1. Mainly used as a nutritional supplement. It is easy to generate burnt flavor and chocolate flavor by co heating with glucose, which has the effect of aroma enhancement. It can also be used for biochemical research.

2. Feed Nutritional fortifier ， threonine It is an essential amino acid. Threonine is often added to minors Piglet And poultry feed Pig feed Second of Restricted amino acid And the third limiting amino acid of poultry feed. Added to wheat, barley Such as grain based feed.

3. Nutritional additives are also used to prepare amino acid infusion and comprehensive amino acid preparations.

4. For Peptic ulcer Adjuvant treatment. It can also cure anemia and angina Aortitis 、 Cardiac insufficiency etc. cardiovascular system Illness.

5. Threonine (L-threonine) is composed by W C. Rose went from fibrin It was separated and identified from the hydrolysate, and has been proved to be the last to be found essential amino acid , it is the second or third of livestock and poultry Restricted amino acid It plays an extremely important physiological role in animals. Such as promoting growth and improving immune function; Balance the amino acids in the diet, so that the proportion of amino acids is closer to Ideal protein So as to reduce the requirements of livestock and poultry on protein content in feed. lack threonine , which can lead to reduced animal feed intake, growth obstruction, decreased feed utilization, immunosuppression and other symptoms. In recent years, lysine and methionine synthetics have been widely used in feed, and threonine has gradually become a limiting factor affecting animal production performance. Further research on threonine will help effectively guide livestock and poultry production.

Threonine (L-threonine) is an amino acid that cannot be synthesized by animals themselves but is badly needed, and can be used to accurately balance feed amino acid composition To meet the needs of animal growth and maintenance, improve weight gain and Lean meat percentage , lower Feed meat ratio ； It can improve the nutritional value of feed materials with low amino acid digestibility, and improve the production performance of low energy feed; Can reduce feed crude protein Level, improve feed nitrogen utilization rate and reduce feed cost; It can be used for raising pigs, chickens, ducks and high-grade aquatic products. L— threonine It is based on the principle of bioengineering corn starch And other raw materials are produced through liquid deep fermentation and refining feed additive 。 Adjustable feed Amino acid balance It can promote growth, improve meat quality, improve the nutritional value of feed materials with low amino acid digestibility, and produce low protein feed, which helps to save protein resources, reduce the cost of feed materials, reduce the nitrogen content in livestock manure and urine, and reduce the ammonia concentration and release rate in livestock and poultry houses. Widely used to add Piglet Feed, breeding pig feed, broiler feed prawn Feed and eel feed.^[1]

6. Threonine (L-threonine) in vivo Catabolism Middle, yes=not passed Deamination and Transamination , but directly through Threonine dehydratase 、 threonine dehydrogenase And threonine Aldolase Amino acids that catalyze the conversion to other substances, such as threonine, can be converted to butyryl Coenzyme A 、 Succinyl coenzyme A 、 serine 、 glycine Etc. In addition, excess threonine can increase lysine - α - ketone Gluconic acid Reductase activity. Adding proper amount of threonine in the diet can eliminate the body caused by excessive lysine Weight gain Down, liver Muscle tissue Medium protein/deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)/DNA ratio decreased. Addition of threonine can also reduce Tryptophan Or growth inhibition caused by excessive methionine. It is reported that the absorption of threonine by chicken is mostly duodenum , crop and Glandular stomach The absorbed threonine is rapidly transformed into liver protein and deposited in the body.^[1]

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