Activity Determination, Kinetic Analyses and Isoenzyme Identification of Gamma Glutamyltransferase in Human Neutrophils
2005
Sener, Azize (Marmara University, Haydarpasa-Istanbul, Turkdy), E-mail: [email protected] | Yardimci, Turay (Marmara University, Haydarpasa-Istanbul, Turkdy)
Gamma-glutamyltransferase (GGT, EC 2.3.2.2) which hydrolyzes glutathione (GSH), is required for the maintenance of normal intracellular GSH concentration. GGT is a membrane enzyme present in leukocytes and platelets. Its activity has also been observed in human neutrophils. In this study, GGT was purified from Triton X-100 solubilized neutrophils and its kinetic parameters were determined. For kinetic analyses of transpeptidation reaction, γ-glutamyl p-nitroanilide was used as the substrate and glycylglycine as the acceptor. Apparent Km values were determined as 1.8 mM for γ-glutamyl p-nitroanilide and 16.9 mM for glycylglycine.
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