[Kinetic characteristics of 6-phosphogluconate dehydrogenase from bull adrenal cortex].
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.
Senkevich
S B
SB
Martynchik
D I
DI
Vinogradov
V V
VV
D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D002384:Catalysis; D002417:Cattle; D007700:Kinetics; D009249:NADP / Q000378:metabolism; D010734:Phosphogluconate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D009249:NADP; D010734:Phosphogluconate Dehydrogenase
Kineticheskie kharakteristiki 6-fosfogliukonatdegidrogenazy iz kory nadpochechnikov byka.