Enzymatic synthesis of cyclic amino acids by N-methyl-l-amino acid dehydrogenase from Pseudomonas putida

A new enzymatic system for the synthesis of enantiomerically pure cyclic amino acids (CAA) from the corresponding diamino acids or racemic CAA is described. α,ω-Diamino acids were oxidized to α-keto acids with amino acid oxidases (AAO). The α-keto acids were spontaneously transformed into cyclic imino acids in the reaction medium. The resulting imines were reduced to the l-form CAA with N-methyl-l-amino acid dehydrogenase (NMAADH) from Pseudomonas putida ATCC12633 using NADPH as a cofactor. l-Form CAA were also obtained from racemic CAA using d-amino-acid oxidase and NMAADH. Using this method, a new compound [1,4]-thiazepane-3-carboxylic acid (Fig. 1) was synthesized from aminopropylcystein.

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