L-Aspartic acid is the L-form of the aspartic acid. It is one of the 20 amino acids that used in the protein synthesis. It is the non-essential amino acids for humans as it can be synthesized in vivo. It is important in the synthesis of other amino acids and some nucleotides, and is a metabolite in the citric acid and urea cycles. In animals, it may be used as a neurotransmitter. It can be chemically synthesize from the diethyl sodium phthalimidomalonate. Currently, almost all the aspartic acids are manufactured in China. Its application include being used as low calorie sweetener (as the part of the aspartame), scale and corrosion inhibitor, and in resins. One of its growing applications is for the manufacturing of biodegradable superabsorbent polymer, polyaspartic acid. It can also be used in fertilizer industry to improve water retention and nitrogen uptake.
ChEBI: The L-enantiomer of aspartic acid.
Endogenous NMDA receptor agonist.
L-aspartic acid is used as a dietary supplement, it can be blended with minerals to make compounds like potassium aspartate, copper aspartate, manganese aspartate, magnesium aspartate, zinc aspartate and more. Increasing the absorption, and hence utilization potentials, of these minerals via the addition of aspartate induces certain health benefits. Many athletes use L-aspartic acid-based mineral supplements orally to enhance their performance capacities.
Aspartic acid and glutamic acid play important roles as general acids in enzyme active centers, as well as in maintaining the solubility and ionic character of proteins. It can help promote a robust metabolism, and is sometimes used to treat fatigue and depression.
Aspartic acid is used as a component of parenteral and enteral nutrition. In pharmaceutical agents aspartic acid is used as an ammoniac detoxicating agent, hepar function accelerator and fatigue refresher.
It is used as an electrolyte supplement for aminophenol transfusion, inorganic ion supplement (K+, Ca+, etc.) and fatigue restorer. Potassium magnesium aspartate injection or oral solution can be used for arrhythmia, premature beat, tachycardia, hypokalemia, hypomagnesemia, heart failure, myocardial infarction, angina pectoris, hepatitis, cirrhosis and other diseases caused by cardiac glycoside poisoning. Due to its low toxicity, this product cannot be injected without dilution, and the patients with renal insufficiency and atrioventricular conduction block should use it with caution.
The product is white crystal or crystalline powder, slightly sour in taste. Soluble in boiling water, slightly soluble in water at 25℃(0.5%), freely soluble in dilute acid and sodium hydroxide solution and insoluble in ethanol and ethyl ether. It decomposes when heated to 270 ℃. Its isoelectric point is 2.77 and its specific rotation is associated with the soluble solvent. It is dextral in the acid solution and water solution, but levorotary in the alkali solution. [α]25D+5.05 (C=0.5-2.0 g/ml, H2O). Combined with HNO2, alcohol or acyl chloride, it can produce L- malic acid, ester and amide respectively. It is the ingredient of unripe sugarcane and beet molasses.
L- aspartic acid is mainly produced by enzymatic method. L- aspartase acts on the fumaric acid and ammonia, that is, which generates L- aspartic acid.
- Strain Culturing: Eschrichia coli Asl.881 was cultured. The common meat juice medium is agarslantculture-medium. The vase medium comprises corn steep liquor 7.5%, fumaric acid 2.0% and MgSO4 7H2O 0.02%. Adjust the pH value of solution to 6.0 with ammonia water, then put 50-100ml culture medium into 500ml cone bottle after boiling and filtering. Take the fresh cultivated seeds on the slope or in the liquid, inoculate culture medium in shake flask, shake overnight at 37℃, adjust pH to 5.0 with 1mol/L HCl after enlarging culture step by step to 1000-2000L, cool it to room temperature after keeping 45℃ for 1h, centrifuge in rotary supercentrifuge and collect the thallus including aspartase.
- Immobilize aspartase: Make a bioreactor to take out 20kg E.Coli wet cell, suspend it in the culture supernatant after centrifugation in 80L (or 80L saline), keep it at 40℃ and then add 90L 12% gelatin solution and 1.0% glutaraldehyde solution, which should be held 40℃. Stir well, set aside to cool down and solidify, soak in 0.25% glutaraldehyde solution, hold 5℃ after an overnight, cut into small pieces ( 3-5 mm3) , soak in 0.25% glutaraldehyde solution at 5℃ for a night, take it out and elut with water, drain to obtain immobilized E.Coli containing aspartase and load it into filled bioreactor in reserve.
- Conversion: The solution of 1 mol/L of ammonium fumarate (including 1mmol/L MgCl2, pH8.5) substrate, which keeps 37℃, flows through a bioreactor at a constant speed (SV) continuously in the case of controlling the maximum conversion rate over 95% and then the conversion solution is obtained.
- Roughhew and refine: Add 1 mol/L of HCl into the conversion solution gradually to adjust pH valkue to 2.8, place at 5℃ overnight for crystallizing, filter to prepare crystallization, drain after water washing, drying at 105℃ to obtain L- aspartic acid crude. Use dilute ammonia to recrystallize, dissolve into 15% solution (pH5.0) with ammonia, add 1% activated carbon, stir and fade for 1h when heat to 70℃, filter immediately to remove slag, cool the filtrate, hold 5℃ overnight for crystallizing, filter to get crystallization and obtain the L-Aspartic acid finished products after vacuum drying at 85℃.