Kinetic mechanism of human erythrocyte acidic isoenzyme rho.
The kinetic mechanism has been determined for human glutathione S-transferase rho (rho), an isoenzyme related to the human pi (pi) isoenzyme. The kinetic mechanism was investigated by both non-linear regression studies and the analysis of primary and secondary plots, utilizing initial rate and product inhibition data. It was concluded that human isoenzyme rho obeys a random sequential Bi-Bi rapid equilibrium mechanism with the formation of an enzyme-substrate-product (enzyme-CDNB-conjugate) dead-end complex. The values of KCDNB, KGSH and Kconjugate were 0.70 +/- 0.11, 0.12 +/- 0.02 and 0.016 +/- 0.004 mM, respectively. Comparison of the kinetic mechanism and kinetic parameters obtained for glutathione S-transferase isoenzyme rho with other class pi isoenzymes showed similarities at the primary kinetic level.
Thumser
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AE
Department of Medical Biochemistry, University of Cape Town Medical School, Observatory, South Africa.
Ivanetich
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KM
D004137:Dinitrochlorobenzene / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology*; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics
D004137:Dinitrochlorobenzene; D007527:Isoenzymes; D005982:Glutathione Transferase