[Kinetic characteristics of 6-phosphogluconate dehydrogenase from bull adrenal cortex].

Autor: Senkevich SB, Martynchik DI, Vinogradov VV
Jazyk: ruština
Zdroj: Ukrainskii biokhimicheskii zhurnal (1978) [Ukr Biokhim Zh (1978)] 1989 Sep-Oct; Vol. 61 (5), pp. 92-5.
Abstrakt: The hyperbolic dependence of the initial rate of 6-phosphogluconate dehydrogenase-catalyzed reaction on 6-phosphogluconate and NADP concentrations has been established. The Lineweaver-Burk plots of V0 against concentration of one substrate with constant unsaturating concentrations of another substrate cross left from the ordinate axis. The Km value for 6-phosphogluconate is equal ot 0.035 mM, for NADP--0.018 mM. It has been shown that NADPH inhibits 6-phosphogluconate dehydrogenase by the competitive type with respect to NADP and by the noncompetitive one with respect to 6-phosphogluconate. Ribulose-5-phosphate inhibits the reaction by the mixed type with respect to NADP and by the noncompetitive type with respect to 6-phosphogluconate. Kinetic data are in agreement with the consecutive mechanism of the reaction: the first substrate is NADP, the last product--NADPH. The Arrhenius plot for the reaction shows a break at 27 degrees C.
Databáze: MEDLINE