THIOLS, GOLD-THIOLS, ZINC-THIOLS AND THE REDOX STATE OF HEMOGLOBIN

The beta subunit of human hemoglobin can be oxidized site-specifically through beta-Cys-93 by Cu(II)(His)2. A series of thiol ligands, gold thiols and zinc(II) inhibit this oxidation. The thiol inhibitors forme d a transient ternary intermediate involving Cu(I) with consequent inh ibition of electron transfer from the Fe(Il)-heme. The intermediate le d to the formation of a disulfide at the beta-Cys-93 site. The most ef fective thiols achieved maximum inhibition at one equivalent per beta heme. Gold thiols and zinc complexes inhibited heme oxidation by compe ting with the Cu(II)(His)2 for the beta-Cys-93 site.