Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10820585 | Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology | 2005 | 9 Pages |
Abstract
d-Amino acid oxidase of carp (Cyprinus carpio) hepatopancreas was overexpressed in Escherichia coli cells and purified to homogeneity for the first time in animal tissues other than pig kidney. The purified preparation had a specific activity of 293 units mgâ1 protein toward d-alanine as a substrate. It showed the highest activity toward d-alanine with a low Km of 0.23 mM and a high kcat of 190 sâ1 compared to 10 sâ1 of the pig kidney enzyme. Nonpolar and polar uncharged d-amino acids were preferable substrates to negatively or positively charged amino acids. The enzyme exhibited better thermal and pH stabilities than several yeast counterparts or the pig kidney enzyme. Secondary structure topology consisted of 11 α-helices and 17 β-strands that differed slightly from pig kidney and Rhodotorula gracilis enzymes. A three-dimensional model of the carp enzyme constructed from a deduced amino acid sequence resembled that of pig kidney d-amino acid oxidase but with a shorter active site loop and a longer C-terminal loop. Judging from these characteristics, carp d-amino acid oxidase is close to the pig kidney enzyme structurally, but analogous to the R. gracilis enzyme enzymatically in turnover rate and pH and temperature stabilities.
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Authors
Mohammed Golam Sarower, Shigeru Okada, Hiroki Abe,