期刊
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
卷 1794, 期 2, 页码 324-334出版社
ELSEVIER
DOI: 10.1016/j.bbapap.2008.10.007
关键词
Alr1529; Arylesterase; Variant SGNH hydrolase; Anabaena sp.; Kinetics
资金
- Department of Science and Technology, New Delhi, India
- Novartis Research Foundation
Alr1529, a serine hydrolase from the cyanobacteria Anabaena sp. strain PCC 7120 is a member of the SGNH hydrolase superfamily. Biochemical characterization of the purified enzyme revealed that the protein is a dimer in solution and is specific for aryl esters of short chain carboxylic acids. The enzyme was regio-selective for alpha-naphthyl esters with maximum activity at pH 7.5 and has a broad optimal temperature range (25-45 degrees C). A structure based comparison of Alr-1529 with other superfamily members confirmed the presence of the catalytic triad (Ser17-Asp179-His182) and oxyanion hole (Ser17-Arg54-Asn87) residues. Alr1529 exhibits a previously undescribed variation in the active site wherein a conserved Gly, a proton donor making up the oxyanion hole in the SGNH hydrolases, is substituted by Arg54. Site-directed mutagenesis studies suggest that Arg54 is crucial for substrate binding and catalytic activity. Ser17 plays a very crucial role in catalysis as evident from the 50-fold lower activity of the S17A mutant. (C) 2008 Elsevier B.V. All rights reserved.
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