Methods for racemizing N-acylamino acids and producing optically active amino acids

A method for racemizing an N-acylamino acid, the method comprising contacting a microorganism producing a racemase, or extract thereof, with an optically active N-acylamino acid, wherein the microorganism is a transformant expressing a polypeptide encoded by a polynucleotide selected from the group consisting of:

• (a) a polynucleotide comprising the coding region of the nucleotide sequence of SEQ ID NO:1;
• (b) a polynucleotide encoding a polypeptide comprising the amino acid sequence of SEQ ID NO:2;
• (c) a polynucleotide that encodes a polypeptide having at least 80% sequence identity to SEQ ID NO:2 and has activity of an N-acylamino acid racemase having the enzymatic properties of (1) and (2) below;
• and
• (d) a polynucleotide encoding a polypeptide comprising the amino acid sequence of SEQ ID NO:2 in which one or more amino acids are substituted, deleted, inserted, and/or added, and having activity of an N-acylamino acid racemase having the enzymatic properties of (1) and (2) below, wherein the number of amino acids that are substituted, deleted, inserted, and/or added, is 30 or less;
• (1) action:
• the racemase racemizes N-acylamino acids, and
• (2) substrate specificity:
• the racemase has relative activity of at least 50 or higher for each of N-acylalanine, N-acylaspartic acid, N-acylleucine, N-acylvaline, and N-acyltryptophan among N-acylamino acids when the activity for N-acylmethionine is taken as 100.