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dc.contributor.authorSaowapa Duangpanen_US
dc.contributor.authorSarawut Jitrapakdeeen_US
dc.contributor.authorAbdussalam Adina-Zadaen_US
dc.contributor.authorLindsay Byrneen_US
dc.contributor.authorTonya N. Zeczyckien_US
dc.contributor.authorMartin St. Mauriceen_US
dc.contributor.authorW. Wallace Clelanden_US
dc.contributor.authorJohn C. Wallaceen_US
dc.contributor.authorPaul V. Attwooden_US
dc.contributor.otherMahidol Universityen_US
dc.contributor.otherUniversity of Western Australiaen_US
dc.contributor.otherMarquette Universityen_US
dc.contributor.otherUniversity of Wisconsin Madisonen_US
dc.contributor.otherUniversity of Adelaideen_US
dc.identifier.citationBiochemistry. Vol.49, No.15 (2010), 3296-3304en_US
dc.description.abstractThe roles of Arg548 and Gln552 residues in the active site of the carboxyl transferase domain of Rhizobium etli pyruvate carboxylase were investigated using site-directed mutagenesis. Mutation of Arg548 to alanine or glutamine resulted in the destabilization of the quaternary structure of the enzyme, suggesting that this residue has a structural role. Mutations R548K, Q552N, and Q552A resulted in a loss of the ability to catalyze pyruvate carboxylation, biotin-dependent decarboxylation of oxaloacetate, and the exchange of protons between pyruvate and water. These mutants retained the ability to catalyze reactions that occur at the active site of the biotin carboxylase domain, i.e., bicarbonate-dependent ATP cleavage and ADP phosphorylation by carbamoyl phosphate. The effects of oxamate on the catalysis in the biotin carboxylase domain by the R548K and Q552N mutants were similar to those on the catalysis of reactions by the wild-type enzyme. However, the presence of oxamate had no effect on the reactions catalyzed by the Q552A mutant. We propose that Arg548 and Gln552 facilitate the binding of pyruvate and the subsequent transfer of protons between pyruvate and biotin in the partial reaction catalyzed in the active site of the carboxyl transferase domain of Rhizobium etli pyruvate carboxylase. © 2010 American Chemical Society.en_US
dc.rightsMahidol Universityen_US
dc.subjectBiochemistry, Genetics and Molecular Biologyen_US
dc.titleProbing the catalytic roles of arg548 and gln552 in the carboxyl transferase domain of the rhizobium etli pyruvate carboxylase by site-directed mutagenesisen_US
Appears in Collections:Scopus 2006-2010

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