Bozcaarmutlu, AzraArınç, Emel2021-06-232021-06-2320070887-2333https://doi.org/10.1016/j.tiv.2006.10.002https://hdl.handle.net/20.500.12491/609731st Congress of the Federation-of-European-Biochemical-Societies (FEBS) -- JUN 24-29, 2006 -- Istanbul, TURKEYInformation on the mechanism of metal ion inhibition of NADPH-cytochrome P450 reductase is limited. The purpose of the present paper was to elucidate in vitro effect of Hg(+2), Cd(+2), Ni(+2), Cr(+3) and Zn(+2) ions on the purified mullet NADPH-cytochrome P450 reductase. NADPH-cytochrome P450 reductase was purified from detergent-solubilized liver microsomes from leaping mullet (Liza saliens). All of the metal ions caused inhibition of the enzyme activity except Zn(+2). At 50 mu M metal concentration, Hg(+2) inhibited the cytochrome P450 reductase activity completely (100%), while, at the same concentrations, Cd(+2), Cr(+3) and Ni(+2) caused 66%, 65% and 37% inhibition, respectively. At 50 mu M metal concentration, Zn(+2) had no apparent effect on cytochrome P450 reductase activity. The IC(50) values of HgCl(2), CrCl(3), CdCl(2) and NiCl(2) were estimated to be 0.07 mu M, 24 mu M, 33 mu M and 143 mu M, respectively. Of the metal ions tested, Hg(+2) exhibited much higher inhibitory effect at lower concentrations, so it was evidently a more potent inhibitor than the others. All four metal ions displayed noncompetitive type of inhibition mechanism for the purified reductase as analyzed by Dixon plot. K(i) values of Hg(+2), Cr(+3), Cd(+2) and Ni(+2) were calculated from Dixon plots as 0.048 mu M, 18 mu M, 73 mu M and 329 mu M, respectively. (c) 2006 Elsevier Ltd. All rights reserved.eninfo:eu-repo/semantics/openAccessNoncompetitive InhibitionLeaping mullet (Liza saliens)NADPH-cytochrome p450 ReductaseMercuryCadmiumNickelChromiumZincConference Object10.1016/j.tiv.2006.10.002213408416171137462-s2.0-33947357707Q2WOS:000246548200011Q2