Journal article

Publication year: 1997

Pages: 1307-1313

Journal: Biochemical Pharmacology

Volume number: 54

Issue number: 12

ISSN: 0006-2952

DOI Link: https://doi.org/10.1016/S0006-2952(97)00348-1

Publisher: Elsevier

Abstract: 
Human glutathione reductase (GR) and rat liver glutathione-S-transferases (GSTs) had been shown to be inhibited by the nitric oxide (NO) carrier S-nitroso-glutathione (GSNO). Me have now extended these studies by measuring the effects of dinitrosyl-iron complexed thiols (DNIC-[RSH](2)) on human GR, CST and glutathione peroxidase. DNIC-[RSH](2) represent important transport forms of NO but also of iron ions and glutathione in vivo. Human GR was found to be inhibited by dinitrosyl-iron-di glutathione (DNIC-[GSH](2)) and dinitrosyl-iron-di-L-cysteine (DNIC-Cys(2)) in two ways: both compounds were competitive with glutathione disulfide (GSSG), the inhibition constant (K-i) for reversible competition of DNIC-[GSH](2) with GSSG being approximately 5 mu M; preincubating GR for 10 min with 4 mu M DNIC-[GSH](2) and 40 mu M DNIC-Cys(2), respectively, led to 50% irreversible enzyme inactivation. More than 95% GR inactivation was achieved by incubation with 36 mu M DNIC-[GSH](2) for 30 min. This inhibition depended on the presence of NADPH. Absorption spectra of inhibited GR showed that the charge-transfer interaction between the isoalloxazine moiety of the prosthetic group flavin adenine dinucleotide (FAD) and the active site thiol Cys63 is disturbed by the modification. Cys(2) and FAD could be ruled out as sites of the modification. Isolated human placenta glutathione-S-transferase and GST activity measured in hemolysates were also inhibited by DNIC-[GSH](2). This inhibition, however, was reversible and competitive with reduced glutathione, the K-i being 20 nM. The inhibition of GST induced by GSNO was competitive with reduced glutathione (GSH) (K-i = 180 mu M) and with the second substrate of the reaction, 1-chloro-2,4,-dinitrobenzene (K-i = 170 mu M). An inhibition of human glutathione peroxidase by GSNO or DNIC-[RSH](2) was not detectable. Inactivation of GR by DNIC-[GSH](2) is by two orders of magnitude more effective than modification by GSNO; this result and the very efficient inhibition of GST point to a role of DNIC-[RSH](2) in glutathione metabolism. (C) 1997 Elsevier Science Inc.

Harvard Citation style: Keese, M., Böse, M., Mülsch, A., Schirmer, R. and Becker, K. (1997) Dinitrosyl-dithiol-iron complexes, nitric oxide (NO) carriers in vivo, as potent inhibitors of human glutathione reductase and glutathione-S-transferase, Biochemical Pharmacology, 54(12), pp. 1307-1313. https://doi.org/10.1016/S0006-2952(97)00348-1

APA Citation style: Keese, M., Böse, M., Mülsch, A., Schirmer, R., & Becker, K. (1997). Dinitrosyl-dithiol-iron complexes, nitric oxide (NO) carriers in vivo, as potent inhibitors of human glutathione reductase and glutathione-S-transferase. Biochemical Pharmacology. 54(12), 1307-1313. https://doi.org/10.1016/S0006-2952(97)00348-1