title: Fluorescein mercuric acetate specifically displaces zinc from cytochrome oxidase.
abstract: Treatment of beef heart cytochrome oxidase with fluorescein mercuric acetate (FMA) was found to specifically displace zinc from the enzyme and inhibit the steady-state activity in a parallel fashion. The native cytochrome oxidase preparation contained 2.3 Cu: 2.0 Fe: 1.1 Zn: 0.9 Mg. Addition of 2 equivalents of FMA inhibited the activity by 50% and displaced 60% of the zinc from the enzyme, but did not affect the copper, iron or magnesium content. The pre-steady-state reduction of cytochrome oxidase by ferrocytochrome c was not affected by the FMA treatment, in contrast to the inhibition of steady state activity. These results suggest a possible structural or functional role for zinc in cytochrome oxidase.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005452:Fluoresceins / Q000378:metabolism* / Q000494:pharmacology; D066298:In Vitro Techniques; D008627:Mercuric Chloride / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology; D009941:Organomercury Compounds / Q000378:metabolism* / Q000494:pharmacology; D015032:Zinc / Q000378:metabolism*
chemical_list: D005452:Fluoresceins; D009941:Organomercury Compounds; C001673:fluorescein mercuric acetate; D008627:Mercuric Chloride; D003576:Electron Transport Complex IV; D015032:Zinc