Analysis of kinetic properties of gamma-glutamyl transpeptidase from rat kidney.
The initial rate kinetics of rat kidney gamma-glutamyl transpeptidase were measured using L-gamma-glutamyl-p-nitroanilide and glycyl-glycine as the donor and the acceptor substrate, respectively. Experimental data were fitted with the initial rate equation, and the obtained results indicated that: (1) Michaelis constants for transpeptidation (Kb), autotranspeptidation (Ka), and hydrolysis (Kh) are 8.56 mmol/l, 2.02 mmol/l and 0.005 mmol/l, respectively. (2) The maximum rate of transpeptidation (Vb) exceeds that of hydrolysis (Vh) and autotranspeptidation (Va) 160 times and 5 times, respectively. (3) A comparison of the ratios of maximal rate: Michaelis constant of individual reactions shows that hydrolysis is approximately 10 times more efficient than the remaining two reactions. (4) Under routine conditions used for gamma-glutamyl transpeptidase estimation, transpeptidation is the prevalent reaction.
Dvoráková
L
L
Institute of Physiology, Academy of Sciences of the Czech Republic, Czech Republic.
Krůsek
J
J
Stastný
F
F
Lisý
V
V
D000818:Animals; D005260:Female; D005973:Glutamine / Q000031:analogs & derivatives; D006033:Glycylglycine; D006868:Hydrolysis; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D005973:Glutamine; D006033:Glycylglycine; C001300:gamma-glutamine-4-nitroanilide; D005723:gamma-Glutamyltransferase