Substrate Specificity and Stoichiometry of N^α-Benzyloxycarbonyl Amino Acid Urethane Hydrolase from Streptococcus faecalis R ATCC 8043

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The substrate specificity of a new enzyme, N^α-benzyloxycarbonyl amino acid urethane hydrolase, was investigated. The enzyme hydrolyzed N^α-benzyloxycarbonyl-glycine and -alanine, and N^α-benzoyl-glycine and -alanine. N^α-benzyloxycarbonyl-glycine was hydrolyzed to give equimolar benzyl alcohol and glycine. Equimolar benzoic acid and glycine were produced from N^α-benzoyl-glycine by the enzyme reaction.
The Km, k_o, and k_o/Km values were measured for several substrates. The k_o values varied widely with the amino acid residues. N^α-benzyloxycarbonyl-glycine and N^α-benzoyl-glycine produced relatively small changes in the Km values (0.36-0.10mM) and the k_o/Km values (99440-2000M^-1 sec^-1). The rate of hydrolysis is significantly affected by electron-supplying substituents on the benzene ring.