[Purification and various properties of hyaloplasmic NADP-dependent isocitrate dehydrogenase from the rabbit adrenal gland].
NADP-dependent isocitrate dehydrogenase was isolated from the hyaloplasmic fraction of rabbit adrenal glands and purified by ammonium sulfate and polyethylene glycol fractionation and chromatography on DEAE-Sephadex A-50 to a specific activity of 26.8 U/mg with a 53% yield. Polyacrylamide gel electrophoresis revealed one distinct protein band with mobility corresponding to Mr approximately 50 000 in the presence of SDS. Data from gel filtration suggest that the detergent-untreated isocitrate dehydrogenase has a twice as great molecular mass, which is indicative of its dimeric structure of identical subunits. The pH optimum for the adrenal isocitrate dehydrogenase-catalyzed reaction is 7.5-7.7; the apparent activation energy is 61.3 kJ X mol-1. Mn2+ activate the enzyme more effectively than Mg2+. The curve for the dependence of the isocitrate dehydrogenase reaction rate versus D-isocitrate and NADP concentrations is S-shaped. At low substrate or coenzyme concentrations the Hill coefficient is 2.0 and 1.9, respectively, which serves as a kinetic attribute of positive cooperativity of their interaction with isocitrate dehydrogenase. The concentrations of D-isocitrate and NADP providing for the half-maximal rate of the reaction are 3.8 and 6.6 microM, respectively.
D000311:Adrenal Glands / Q000166:cytology / Q000201:enzymology*; D000645:Ammonium Sulfate; D000818:Animals; D002852:Chromatography, Ion Exchange; D004789:Enzyme Activation / Q000187:drug effects; D007521:Isocitrate Dehydrogenase / Q000302:isolation & purification* / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D009249:NADP / Q000502:physiology; D011092:Polyethylene Glycols; D011817:Rabbits
D011092:Polyethylene Glycols; D008345:Manganese; D009249:NADP; D007521:Isocitrate Dehydrogenase; D008274:Magnesium; D000645:Ammonium Sulfate
Ochistka i nekotorye svoĭstva gialoplazmaticheskoĭ NADP-zavisimoĭ izotsitratdegidrogenazy iz nadpochechnikov krolika.