Abstract
(1) The enzymatic procedure of the asymmetric hydrolysis of N-acylated DL-amino acids with the mold acylase was applied for the resolution of DL-tryptophan, DL-leucine and DL-alanine.
(2) Acetylderivatives of DL-tryptophan, DL-leucine and DL-alanine were incubated at 38°C. for 2 days, at approximately 0.1M concentration in water with an appropriate amount of enzyme solution which was prepared from the molded bran.
(3) By this procedure, L-isomers of each amino acid were liberated and the corresponding D-isomers were obtained by acid hydrolysis of the residual acetyl-D-amino acids. Thus, the optical enantiomorphs of tryptophan, leucine and alanine were prepared with a high degree of optical purity.
(4) Acetyl-DL-tryptophan was best resolved by the asymmetric hydrolysis with mold acylase and acetyl-DL-alanine was also a susceptible substrate for mold acylase. Acetyl-DL-leucine was relatively resistant to the enzyme, as compared with the other acylated amino acids so far resolved. An amount of enzyme two and a half times as large as that for acetyl-DL-tryptophan was required for acetyl-DL-leucine.
