N-acylamino acid racemase

M.-R. Kula, Screening, overexpression and characterization of an N-acylamino acid racemase from Amycolatopsis orientalis subsp. lurida, Appl. Microbiol. Biotechnol. 2001, 55, 354-361. 

Takahashi and Hatano of Takeda Chemical Industries, Japan, succeeded in finding a racemase that acts on N-acylamino acids, but not on the corresponding free amino acids, and named it acylamino acid racemase1171. They have established a method of producing optically active a-amino acids from the corresponding D,L-N-acylamino acids by means of the acylamino acid racemase and aminoacylases. 

Tokuyama et al.11721 found that most of acylamino acid racemase-producing strains produce not only acylamino acid racemase but also aminoacylases one of either d- or L-aminoacylase or both of them. Moreover, acylamino acid racemase shows the optimum pH at around 8.0, which is close to that of aminoacylases. Therefore, N-acylamino acid can be converted as a whole into l- or D-amino acids in one step by means of microbial cells of appropriate strains producing either l- or D-aminoacylase in addition to acylamino acid racemase. 

The acylase-catalyzed resolution of /V-acetyl-DL-amino acids is a key commercial process. The racemization of the remaining /V-acetyl-D-amino acid after separation of the L-amino acid must be performed, but adds complexity and cost. Therefore, in situ racemization with a racemase possessing specificity for N-acylamino acids without affecting the stereochemistry of the product L-amino acids is very desirable. The pentameric enzyme from Streptomyces sp. Y-53 specifically catalyzes the racemization of N-acylamino acids without acting on amino acids [182],... 

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