Biochemical characterization of Alr1529, a novel SGNH hydrolase variant from Anabaena

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• 作者：Kiranmayee Bakshy ; Sathyanarayana N. Gummadi ; Narayanan Manoj
• 关键词：Alr1529 ; Arylesterase ; Variant SGNH hydrolase ; Anabaena sp. ; Kinetics
• 刊名：Biochimica et Biophysica Acta - Proteins and Proteomics
• 出版年：2009
• 出版时间：February 2009
• 年：2009
• 卷：1794
• 期：2
• 页码：324-334
• 全文大小：717 K

文摘

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 α-naphthyl esters with maximum activity at pH 7.5 and has a broad optimal temperature range (25–45 °C). A structure based comparison of Alr1529 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.