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ChemicalBook CAS DataBase List L-tert-Leucine
20859-02-3

L-tert-Leucine synthesis

8synthesis methods
The synthesis method of L-tert-Leucine (L-Tle) includes chemical and biological methods. Compared with traditional chemical synthesis, the enzymatic reduction of chiral keto acid to synthesize the corresponding unnatural amino acid has the advantages of high optical purity, mild reaction conditions, high conversion rate, and environmental friendliness. Currently, enzymatic methods have gradually replaced chemical methods. Some previous research on preparing L-tert-leucine using hydrolase, acyltransferase, and amino acid dehydrogenase has been reported. Among them, the preparation of L-tert-leucine using NADH-dependent L-leucine dehydrogenase (LeuDH, EC 1.4.1.9) has exhibited the most industrial potential. In the presence of NADH and free ammonium, LeuDH can catalyze trimethylpyruvate (TMP) to L-tert-leucine[1-3].
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Yield:20859-02-3 80%

Reaction Conditions:

with ammonium hydroxide;D-glucose;ammonium chloride;sodium hydroxide in water; pH=8.3; for 5.5 h;Enzymatic reaction;stereoselective reaction;Time;Reagent/catalyst;

Steps:

2 2.8 Reductive amination of TMP to l-tert-leucine in liter-scale

Bioconversion of TMP to l-tert-leucine was carried out by recombinant whole-cells harboring pET28a-E-G. In a reactor (2L), 1L of water was added to a mixture of 178.2g glucose (0.9mol), 78.1g TMP (0.6mol), 26.8g NH4Cl (0.5mol) and 10.0g of the whole cells of E. coli BL21/pET28a-E-G. The reaction pH was adjusted to 8.5 with NaOH solution. During the reaction process, the pH was automatically adjusted to 8.5 by titrating 50% (v/v) NH3·H2O. When the reaction was terminated, the reaction mixture was heated to 60°C, followed by centrifugation to remove the biocatalysts. The remained solution was adjusted to pH 5.9 and concentrated via rotary evaporator. Then the solution temperature was decreased slowly to 25°C and continued to decrease to 4°C, the l-tert-leucine crystals were obtained.

References:

Li, Jing;Pan, Jiang;Zhang, Jie;Xu, Jian-He [Journal of Molecular Catalysis B: Enzymatic,2014,vol. 105,p. 11 - 17]

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