[The role of various amino acid residues in the functioning of NADP-specific isocitrate dehydrogenase from bovine adrenal cortex cytoplasm].
The modification of SH-groups in the native isocitrate dehydrogenase accessible to 5,5-dithiobis (2-nitrobenzoic acid) (DTNB) is accompanied by the enzyme inactivation. Isocitrate rather than NADP and MnCl2 protects two SH-groups of the enzyme from modification by DTNB and attendant inactivation. The isocitrate dehydrogenase inactivation by DTNB obeys pseudofirst-order reaction kinetics. The number of DTNB-titrated sulphydryl groups does not change after the isocitrate dehydrogenase denaturation by sodium dodecyl sulphate. In the presence of manganese ions isocitrate and to a lesser extent NADP protect isocitrate dehydrogenase from the inactivation induced by 2,3-butanedione, a specific modifier of arginine residues. It has also been shown that the methylene blue-sensitized photoinactivation of the enzyme associated with the photooxidation of histidine residues decreases in the presence of NADP. These data provide evidence for an essential role of the SH-groups, arginine residues and, probably, histidine in the functioning of NADP-dependent isocitrate dehydrogenase from adrenal cortex.
Senkevich
S B
SB
Taranda
N I
NI
Strumilo
S A
SA
Vinogradov
V V
VV
D000302:Adrenal Cortex / Q000201:enzymology* / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D007521:Isocitrate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D000596:Amino Acids; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+)
Rol' nekotorykh aminokislotnykh ostatkov v funktsionirovanii NADP-spetsifichnoĭ izotsitratdegidrogenazy iz tsitoplazmy kory nadpochechnikov byka.