threonine

amino acid

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

Threonine, a Organic compound , chemical formula is C four H nine NO three , Yes optical rotation , is a must amino acid It is mainly used in medicine, chemical reagent, food fortifier, feed additive, etc.

Chinese name: threonine
Foreign name: Threonine
chemical formula: C four H nine NO three

molecular weight: one hundred and nineteen point one one nine
CAS login number: 72-19-5 (L-type)
EINECS login number: 200-774-1 (L-type)

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It is made by W C. Rose was isolated and identified from fibrin hydrolysate in 1935. In 1936, Meger studied its spatial structure Threose So it is named threonine. Threonine has four isomers, which naturally exist and have physiological effects on the body L-threonine 。

Metabolic pathway

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The metabolic pathway of threonine in the body is different from that of other amino acids Threonine dehydratase (TDH) and threonine dease (TDG) and Aldolase An amino acid that catalyzes conversion to other substances. The main ways are: metabolize to glycine and acetaldehyde ； It is metabolized to aminoalanic acid, glycine and acetyl COA through TDG; Metabolized to propionic acid and α- Aminobutyric acid.

purpose

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Threonine is an important nutritional enhancer, which can strengthen grains, cakes and dairy products. Like tryptophan, it can alleviate human fatigue and promote growth and development. In medicine, because the structure of threonine contains hydroxyl groups, it has a water holding effect on human skin, combines with oligosaccharide chains, plays an important role in protecting cell membranes, and can promote phospholipid synthesis and fatty acid oxidation in vivo. Its preparation has the medicinal effect of promoting human development and anti fatty liver, and is a component of compound amino acid infusion. At the same time, threonine is also the raw material for manufacturing a class of highly effective and hypoallergenic antibiotics - monoamidomycin.

Main food sources: fermented food (grain products), eggs, chrysanthemum, milk, peanuts, rice, carrots, leafy vegetables papaya 、 alfalfa etc.

Threonine is used in medicine, chemical reagent, food fortifier, feed additive, etc. In particular, the amount of feed additive increases rapidly. It is often added to the feed of juvenile piglets and poultry, which is the second limiting amino acid of pig feed and the third limiting amino acid of poultry feed.

With the improvement of people's living standards and the development of breeding industry, threonine, as an amino acid for feed, is widely used to add piglet feed, breeding pig feed, broiler feed, shrimp feed and eel feed. It has the following characteristics:

(1) It can adjust the balance of amino acids in feed and promote growth;

(2) It can improve meat quality;

(3) It can improve the nutritional value of feed materials with low amino acid digestibility;

(4) It can produce low protein feed, which helps to save protein resources;

(5) It can reduce the cost of feed raw materials;

(6) It can reduce the nitrogen content in the feces and urine of livestock and poultry, and the ammonia concentration and release rate in livestock and poultry houses.

Necessity of feed application

At present, domestic feed resources are relatively scarce, especially protein feed such as soybean meal and fish meal, which seriously restricts the development of animal husbandry. Threonine is usually the second or third limiting amino acid in pig feed and the third or fourth limiting amino acid in poultry feed. With the wide application of lysine and methionine synthetics in formula feed, it has gradually become the main limiting factor affecting the production performance of livestock and poultry, especially after the addition of lysine in low protein diet, Threonine became the first limiting amino acid for growing pigs.

If threonine is not used in the feed, the adjustment of threonine in the feed can only rely on protein raw materials. Protein raw materials contain not only threonine, but also other essential and non essential amino acids. As a result of using protein raw materials instead of threonine to adjust the balance of amino acids, the amino acid balance of the feed cannot be improved as much as possible, The waste of a large number of essential amino acids cannot be further reduced, and the feed formulation cost cannot be further reduced. It can be said that threonine is a threshold that must be crossed to improve the amino acid balance, and it is a bottleneck problem that all formulators cannot avoid.

The use of threonine can reduce the waste of essential and nonessential amino acids, or it can reduce the level of crude protein in the feed. Its reason is the same as the use of lysine hydrochloride. The level of crude protein in the feed can be reasonably reduced through the use of crystal amino acids. The production performance of animals will not be damaged, but may be improved.

Dosage added in feed

The threonine requirement should be determined according to the lysine requirement. In production practice, when the lysine and methionine requirements are met, the diet should be formulated according to the digestible threonine in the ileum and the appropriate ratio of threonine and lysine to achieve the purpose of improving the quality of formula feed and the level of animal production. The following is our recommended amount of threonine.

Pig feed	Proportion in feed (%)
Teaching trough period	0.95-1.1
Childcare period	0.75-0.9
Growth period	0.65-0.75
Fattening period	0.45-0.55
Pregnancy	0.42-0.50
Lactation period	0.55-0.65

Chicken feed	Proportion in feed (%)
Broilers 0-3 weeks old	0.68～0.80
Broilers 3-6 weeks old	0.63～0.75
Broilers 6-9 weeks old	0.70～0.72
0-6 weeks old laying hens	0.53～0.70
Laying hens 6-14 weeks old	0.45～0.55
Laying hens 14-20 weeks old	0.40～0.42
Laying hens 20 weeks old	zero point three five

Pharmacopoeia information

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essential information

This product is L-2-amino-3-hydroxybutyric acid, calculated as dry product, containing C four H nine NO three Not less than 98.5%.

character

This product is white crystal or crystalline powder, odorless.

This product is soluble in water and almost insoluble in ethanol.

Specific curl

Take this product, weigh it precisely, add water to dissolve it and dilute it quantitatively to make a solution containing about 60mg per 1mL. Determine according to the law (general rule 0621), and the specific rotation is - 26.0 ° to - 29.0 °.

identify

1. Take 0.1g of this product, add 50mL of water to dissolve it, take 1mL, add 1mL of 2% sodium bicarbonate solution, add 0.2mL of piperidine and 0.1mL of 2.5% sodium nitroferrocyanide solution, the solution will turn blue, and after a few minutes, the solution will turn yellow.

2. Take an appropriate amount of this product and threonine control, add water to dissolve and dilute them respectively to prepare a solution containing about 10mg per 1mL, which is used as the test solution and control solution. According to the method under other amino acids, the position and color of the main spot of the test solution should be the same as that of the control solution.

3. The infrared absorption spectrum of this product should be consistent with the control spectrum (spectrum set 957 figure).

inspect

acidity

Take 0.20g of this product, add 20mL of water to dissolve it, and then measure it according to the law (general rule 0631). The pH value should be 5.0~6.5.

Transmittance of solution

Take 1.0g of this product, add 20mL of water to dissolve it, and then measure the transmittance at 430nm by ultraviolet visible spectrophotometry (general rule 0401), which shall not be less than 98.0%.

chloride

Take 0.30g of this product and check it according to the law (general rule 0801). Compared with the control solution made of 6.0mL of standard sodium chloride solution, it should not be more concentrated (0.02%).

sulfate

Take 1.0g of this product and check it according to the law (general rule 0802). Compared with the control solution made of 2.0mL of standard potassium sulfate solution, it should not be more concentrated (0.02%).

ammonium salt

Take 0.10g of this product and check it according to the law (general rule 0808). It should not be deeper (0.02%) than the control solution made of 2.0mL standard chlorination solution.

Other amino acids

mirror Thin layer chromatography (General Rule 0502) Test.

Test solution: Take a proper amount of this product, add water to dissolve and dilute it to make a solution containing about 10mg per 1mL.

Reference solution: precisely measure 1mL of the test solution, place it in a 200mL volumetric flask, dilute it with water to the scale, and shake it up.

System suitability solution: Take appropriate amount of threonine reference substance and proline reference substance, place them in the same measuring flask, add water to dissolve and dilute them to make a solution containing 10mg and 0.1mg per 1mL respectively.

Chromatographic conditions: silica gel G thin layer plate was used, and n-butanol glacial acetic acid water (6:2:2) was used as the developing agent.

Determination method: take 5 µ L of each of the above three solutions, dab them on the same thin-layer plate, develop them, dry them, spray ninhydrin acetone solution (1 → 50), heat them at 90 ℃ until spots appear, and inspect them immediately.

System suitability requirements: the reference solution should show a clear spot, and the system suitability solution should show two completely separated spots.

Limit: if the test solution shows impurity spots, its color shall not be deeper (0.5%) than the main spot of the control solution, and shall not exceed 1.

Loss on drying

Take this product and dry it at 105 ℃ for 3 hours. The weight loss shall not exceed 0.2% (general rule 0831).

Ignition residue

Take 1.0g of this product and check it according to the law (general rule 0841). The residual residue shall not exceed 0.1%.

ferric salt

Take 1.0g of this product and check it according to the law (general rule 0807). Compared with the control solution made of 1.0mL of standard iron solution, it should not be deeper (0.001%).

heavy metal

Take the residue left under the item of burning residue and check it according to law (the second method of General Rule 0821). The content of heavy metals shall not exceed 10% per million.

Arsenite

Take 2.0g of this product, add 23mL of water to dissolve it, add 5mL of hydrochloric acid, and check according to the law (the first method of general rule 0822), which should meet the requirements (0.0001%).

Bacterial endotoxin

Take this product and check it according to the law (general rule 1143). The amount of endotoxin in every 1g threonine should be less than 12EU. (for injection)

Assay

Take about 0.1g of this product, precisely weigh it, add 3mL of anhydrous formic acid to dissolve it, then add 50mL of glacial acetic acid, titrate it with perchloric acid titrant (0.1mol/L) according to the potentiometric titration method (General Rule 0701), and correct the titration result with a blank test. Every 1mL perchloric acid titrant (0.1mol/L) is equivalent to 11.91mg C four H nine NO three 。