Enzymatic Preparation of a d-Amino Acid from a Racemic Amino Acid or Keto Acid

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• 作者：Ronald L. Hanson ; Brian L. Davis ; Steven L. Goldberg ; Robert M. Johnston ; William L. Parker ; Thomas P. Tully ; Michael A. Montana ; Ramesh N. Patel
• 刊名：Organic Process Research & Development
• 出版年：2008
• 出版时间：November 21, 2008
• 年：2008
• 卷：12
• 期：6
• 页码：1119-1129
• 全文大小：210K
• 年卷期：v.12,no.6(November 21, 2008)
• ISSN：1520-586X

文摘

The d-amino acid (R)-2-amino-3-(7-methyl-1 H-indazol-5-yl)propanoic acid (3) is a key intermediate needed for synthesis of a drug candidate compound. Enzymatic routes to 3 were explored. d-Amino acid 3 was prepared in 68% isolated yield with >99% ee from racemic amino acid 1 using l-amino acid deaminase from Proteus mirabilis expressed in Escherichia coli in combination with a commercially available d-transaminase using d-alanine as amino donor. The d-enantiomer was also prepared in 79% isolated yield with >99% ee from the corresponding keto acid 2 using the d-transaminase with racemic alanine as the amino donor. The rate and yield of this reaction could be accelerated by addition of lactate dehydrogenase (with NAD, formate and formate dehydrogenase to regenerate NADH) to remove the inhibitory pyruvate produced during the reaction. A d-transaminase was purified from a soil organism identified as Bacillus thuringiensis and cloned and expressed in E. coli. The d-transaminase was very effective for the preparation of 3 and gave a nearly complete conversion of 2 to 3 without the need for additional enzymes for pyruvate removal.