As the most abundant amino acid in the human body, glutamine plays an important role in human physiological metabolism and material circulation. Glutamine can be degraded to α-ketoglutarate, and lactate and ATP are the main energy and nitrogen sources for biosynthesis. In addition, glutamine has a good therapeutic effect on severe catabolic diseases (such as severe burns, traumatic surgery), intestinal insufficiency, immune deficiency syndrome and other diseases. When the body is under the pressure of strenuous exercise, disease or injury, the production rate of glutamine cannot meet its own needs, it is very necessary to supplement glutamine in vitro. However, because its solubility is only 36g/L, and it is easy to produce toxic pyroglutamic acid at high temperature, it is difficult to supplement glutamine in vitro, which limits its use.<br/>However, glutamine oligopeptides have outstanding efficacy and safety as glutamine substitutes. L-alanyl-L-glutamine has stable properties and high solubility. It decomposes glutamine in the body within a few minutes.<br/>At present, the Enzymatic Production of dipeptide has attracted extensive attention due to its advantages of low cost, less pollution and high product yield. The biosynthesis method is a method for enzymatically synthesizing alanine dipeptide using L-alanine methyl ester hydrochloride and L-glutamine as substrates. However, this method also has disadvantages such as unstable substrate and easy degradation. The highest yield reported so far is 498 mg/L, therefore, the expression conditions and reaction conditions were optimized and detected by high performance liquid chromatography. By culture temperature (30 °C, 35 °C, 37 °C), induction time (12h, 24h, 36h), induction temperature (16 °C, 18 °C, 20 °C, 25 °C), seed age (OD600=0.2,0.7, 4 ), as well as the optimization of reaction time (0.5h, 1h, 1.5h) and reaction temperature (18 °C, 20 °C, 22 °C, 25 °C), and the substrate conversion rate was determined. The results showed that the catalytic activity of α-amino acid ester acyltransferase was the highest with the reaction time of 0.5h, so the optimal culture conditions were determined to be cultured at 37 °C to OD600=0.7, and induced at 20 °C for 12h; Finally, the yield was increased to 1.03g/L, and the reaction conversion rate was increased to 50%, which effectively improved the utilization rate of the enzyme, and also greatly increased the yield of the glutamate dipeptide.

Enzymatic production of L-Alanyl-L-glutamine by α-Amino Acid Ester Acyltransferase

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