Donor Substrate Specificity of Bovine Kidney Gamma-Glutamyltransferase

dc.contributor.advisorJosephy, David
dc.contributor.authorAgblor, Anita
dc.date.accessioned2012-12-14T17:53:25Z
dc.date.available2012-12-14T17:53:25Z
dc.date.copyright2012-11
dc.date.created2012-11-27
dc.date.issued2012-12-14
dc.degree.departmentDepartment of Molecular and Cellular Biologyen_US
dc.degree.grantorUniversity of Guelphen_US
dc.degree.nameMaster of Scienceen_US
dc.degree.programmeMolecular and Cellular Biologyen_US
dc.description.abstractMammalian γ-glutamyltransferase (GGT) is a glycoprotein consisting of two subunits - a light chain and a heavy chain. The light chain contains the catalytic activity; the heavy chain anchors the protein to the membrane. GGT catalyzes the hydrolysis of the γ-glutamyl isopeptide bond of glutathione conjugates, releasing glutamic acid, or the transfer of the γ-glutamyl group to an acceptor substrate. The specificity of the enzyme for xenobiotic donor substrates has not been fully characterized. The transpeptidation activity of bovine kidney GGT was measured with glycylglycine as acceptor substrate and several glutathione conjugate donor substrates, representative of detoxication products of polycyclic aromatic xenobiotics. HPLC separation with UV detection was used for quantitation. The commonly-used chromogenic donor substrate γ-glutamyl-p-nitroanilide was also tested. Michaelis constants (Km) were obtained for γ-glutamyl-p-nitroanilide (0.74 mM), 4-nitrobenzyl glutathione (0.075 mM), 2,4-dinitrophenyl glutathione (0.30 mM), 4-methylbiphenylyl glutathione (0.12 mM), 1-menaphthyl glutathione (0.23 mM), and 9-methylanthracenyl glutathione (0.22 mM), indicating that enzyme activity is affected, but not strongly, by the nature of the S-substituent attached to glutathione, and there is a slight trend of higher Km values with bulkier aromatic S-substituents.en_US
dc.identifier.urihttp://hdl.handle.net/10214/4894
dc.language.isoenen_US
dc.publisherUniversity of Guelphen_US
dc.rightsAttribution-NonCommercial-NoDerivs 2.5 Canada*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/2.5/ca/*
dc.subjectmercapturic acid pathwayen_US
dc.subjectdetoxicationen_US
dc.subjectglutathione conjugatesen_US
dc.titleDonor Substrate Specificity of Bovine Kidney Gamma-Glutamyltransferaseen_US
dc.typeThesisen_US

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