Bacillusd-stereospecific metallo-amidohydrolase: Active-site metal-ion substitution changes substrate specificity |
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Authors: | Jiro Arima Yoshiko Uesugi Tadashi Hatanaka |
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Affiliation: | 1. Department of Agricultural, Biological, and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan;2. Research Institute for Biological Sciences (RIBS), Okayama, 7549-1 Kibichuo-cho, Kaga-gun, Okayama 716-1241, Japan |
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Abstract: | From investigation of 2000 soil isolates, we identified a d-stereospecific metallo-amidohydrolase that can hydrolyze d-aminoacyl derivatives from the culture supernatant of Bacillus sp. 62E11: 62E11DppA. The enzyme binds two equivalents of zinc, exhibits 70% identity with that of d-aminopeptidases from Bacillus subtilis (DppA). In fact, 62E11DppA has strict specificity toward d-aminoacyl derivatives, i.e., the enzyme shows high activity toward d-aminoacyl benzyl esters and little activity toward d-amino acid containing peptides. Moreover, 62E11DppA exhibits a dramatic change in its activity and substrate specificity by substitution of metal ions in its active site. Based on results of kinetic studies using apo-62E11DppA with various metal ion and substrate concentrations, we propose a possible mechanism for the change in its activity and specificity by substitution of metal ions: the substitution of metal ions in 62E11DppA dramatically changes its activity by altering the substrate specificity. |
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Keywords: | d-stereospecific amidohydrolase Bacillus Substrate specificity Metal substitution d-aminoacyl derivatives |
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