Serine, also known asβ-Hydroxylalanine, chemical formula CthreeHsevenNOthreeSerine is a neutral aliphatic hydroxy amino acid, which is a nonessential amino acid[1]Serine plays a role in the metabolism of fat and fatty acids and the growth of muscle, as well as in the manufacturing and processing of cell membranes, the synthesis of muscle tissues and sheaths surrounding nerve cells.It is mainly used in compound amino acid preparations to supplement amino acids.[1]D-serine is also an important neurotransmitter, and N-methyl-D-aspartate (NMDA) receptor is an important endogenous ligand, both of which play an important role in the central system.The production methods usually include fermentation, protein hydrolysis, chemical synthesis, biological enzyme, etc.
The initial glucose enters the L-serine branching pathway through 3-phosphoglycerate (3-PG) in the glycolysis (EMP) pathway;In the L-serine branch pathway, 3-PG is catalyzed by phosphoglycerate dehydrogenase (SerA) to synthesize 3-phosphate hydroxypyruvate (3-PHP), and then through the intermediate 3-phosphate serine (Ser-P) to synthesize L-serine;In addition, the synthesis of the intermediate serine-P also requires L-glutamic acid (L-Glu) as a precursor to provide amino groups.
The anabolism of D-serine refers to higher animals.
The main source of D-serine is L-serine (L-Ser) racemized by serine racemase (SR). Its metabolism is mainly oxidized and degraded by D-amino acid oxidase (DAAO, EC 1.4.3.3), and finally generates hydroxypyruvate (HPA) and ammonia (NHthree）HPA can be metabolized by glyoxylate reductase/hydroxypyruvate reductase (GRHPR) to produce D-glycerate 3-phosphate, and finally heterogenesis to glucose.
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Serine can be obtained from soybeans, wine fermenting agents, dairy products, eggs, fish, lactalbumin, pods, meat, nuts, seafood, seeds, soybeans, whey and whole wheat.[2]
As far as we know, human access to D-serine includes biosynthesis, protein metabolism, eating, and intestinal bacteria decomposing food. The most important source is D-serine biosynthesis.The main source of D-serine biosynthesis in human body is the conversion of L-Ser from SR containing pyridoxal phosphate.
application
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L-serine, as a basic amino acid of protein, is widely used in medicine, food, cosmetics and other industries.At present, the global market demand for L-serine is 10000 t/year.L-serine is a nonessential amino acid. It is an important precursor involved in the synthesis of intracellular biological substances such as purine, pyrimidine, phospholipid, etc.L-serine is the raw material of compound amino acid infusion, and can also be used as the raw material of light chemical industry[3]。In addition, L-serine is widely used in advanced cosmetics at home and abroad because of its special wettability and moisture retention.
D-serine is one of the most important D-type amino acids in mammals, which is about 1/3 of the total amount of free serine in vivo.Studies have found that there is a high concentration of D-serine in the higher central nervous system of higher animals, including humans, and it plays an important role in neurotransmitters.It was found that D-serine played an important role in the corpus cavernosum and lower esophageal sphincter of mice.
Pharmacopoeia information
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essential information
This product is L-2-amino-3-hydroxypropionic acid, calculated as dry product, containing CthreeHsevenNOthreeNot less than 98.5%
character
This product is white crystal or crystalline powder, odorless.
This product is easily soluble in water, but almost insoluble in ethanol, acetone or ether.
Specific curl
Take this product, weigh it precisely, add 2mol/L hydrochloric acid solution to dissolve it and dilute it quantitatively to make a solution containing about 0.1g per 1mL. Determine according to the law (general rule 0621), and the specific rotation is+14.0 ° to+15.6 °.
identify
1. Take an appropriate amount of this product and serine control, add water to dissolve and dilute them respectively to prepare a solution containing about 0.4mg per 1L, 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.
2. The infrared absorption spectrum of this product should be consistent with the control spectrum (spectrum set 917 figure).
inspect
acidity
Take 0.30g of this product, add 30mL of water to dissolve it, and then measure it according to the law (general rule 0631). The pH value should be 5.5~6.5.
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 0.25g of this product and check it according to the law (general rule 0801). Compared with the control solution made of 5.0mL 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
Test according to thin layer chromatography (general rule 0502).
Test solution: take a proper amount of this product, add water to dissolve and dilute it to make a solution containing about 20mg 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 serine reference substance and methionine reference substance, place them in the same measuring flask, add water to dissolve and dilute them to make a solution containing about 0.4mg per 1mL.
Chromatographic conditions: silica gel G thin layer plate was used, and n-butanol water glacial acetic acid (3:1:1) 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 80 ℃ 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.
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
Not more than 0.1% (general rule 0841).
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 2.0g of this product, add 23mL of water to dissolve it, add 2mL of acetate buffer solution (pH 3.5), and check according to the law (General Rule 0821, Method 1). The content of heavy metals should 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 of serine should be less than 12EU.(for injection)
Assay
Take about 0.1g of this product, precisely weigh it, add 1mL of anhydrous formic acid to dissolve it, add 25mL 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 10.51mg CthreeHsevenNOthree。
