Reversible modification of cysteine residues of NADPH-cytochrome P-450 reductase

• Published in: Biochemical and biophysical research communications Vol. 193; no. 3; p. 1044
• Main Authors: Yelinova, V I, Weiner, L M, Slepneva, I A, Levina, A S
• Format: Journal Article
• Language: English
• Published: United States 30-06-1993
• Subjects: Adenosine Diphosphate - analogs & derivatives; Adenosine Diphosphate - pharmacology; Animals; Binding Sites; Cystamine - pharmacology; Cysteine; Electron Spin Resonance Spectroscopy; Kinetics; Microsomes, Liver - enzymology; NADH Dehydrogenase - antagonists & inhibitors; NADH Dehydrogenase - metabolism; NADPH-Ferrihemoprotein Reductase - antagonists & inhibitors; NADPH-Ferrihemoprotein Reductase - metabolism; Rats
• ISSN: 0006-291X
• DOI: 10.1006/bbrc.1993.1730

A reversible chemical modification of SH-groups of NADPH-cytochrome P-450 reductase is the subject of the present study. The enzyme was modified using first biradical RS-SR (R being the imidazolidine derivative) and a new affinity reductase inhibitor beta-cystamine adenosine diphosphate (ANSSN). These reagents were shown to be covalently bound to reductase SH-groups via the reaction of thiol-disulfide exchange resulting in the loss of reducing activity for cytochrome c. NADP+ protected reductase from inactivation and decreased the extent of the modification by RS-SR. The modification of reductase was reversible: the modified enzyme was partially reactivated with glutathione and dithiothreitol. The method proposed can be used to study both the reductase structure and the reversible inhibition of microsomal monooxygenase systems.