ENZYMATIC RESOLUTION OF RACEMIC AMINO ACIDS

VI. HYDROLYSIS OF VARIOUS N-ACYL DL-AMINO ACIDS BY MOLD ACYLASES

Abstract

1. The acylase activities of the enzyme preparations from Penicillium and Aspergillus on various N-acyl DL-amino acids were measured.
2. Of these acyl derivatives of some fifteen DL-amino acids tested, the acetyl derivatives of aromatic amino acids, namely, tyrosine, phenylalanine and tryptophan and those of basic amino acids, such as arginine and lysine were hydrolyzed by the both mold acylases with almost equall ease.
3. The acetyl derivatives of aliphatic amino acids, such as methionine, alanine and glutamic acid were also susceptible substrates, although the rate of hydrolysis was somewhat lower than those above.
4. Hydroxy amino acids, such as threonine and serine, were tested in form of chloroacetyl derivatives. It was found that chloroacetyl DL-threonine was rather resistant, whereas chloroacetyl DL-serine was susceptible to the acylase.
5. The acetyl derivatives of other amino acids, such as isoleucine, leucine, valine and histidine, were hydrolyzed less easily. Acetyl DL-aspartic acid was the most resistant to the acylase.
6. Co⁺⁺ ion at a comcentration of 10-^{3, 7}M accelerates the enzyme activity on various aryl DL-amino acids by about 10 to 100 per cent, with the exception that the hydrolysis of chloroacetyl DL-valine and acetyl DL-glutamic acid is inhibited.
7. Acylases from Penicillum and Aspergillus are probably the same enzyme.
The authors are grateful to Dr. J. Greenstein of National Institutes of Health, U.S.A. for generous supply of some of the acyl amino acids, to Dr. S. Tatsuoka of Takeda Pharmaceutical Industries for supplying DL-lysiee, and to Miss Isobe and Mrs. Sugimoto for performing the microanalyses. The research was aided by the Ajinomoto Company.