Binding of Iron and Copper to Bovine Heart Mitochondria

摘要: Bovine heart mitochondria were found to bind large amounts of Cu2+, Cu+, Fe2+, and Fe3+ in a rapid, energy-independent reaction. Binding was more than 80% complete within 15 s (the shortest time tested). To prevent disproportionation Cu+ Cu2+ Cu0, cuprous-acetonitrile-perchlorate complex used. added as the 8-hydroxyquinoline or citrate derivative. Of Fe3+, 1.5 2.5 µmoles per mg protein could be bound absence phosphate, while much 4 6 presence phosphate. A Cu2+- Fe2+-dependent Pi uptake observed with cation ratios 1.8, suggestive formation Cu3(PO4)2 Fe3(PO4)2. binding, however, limited about 120 nmoles Km value 0.42 m obtained. The binding copper inhibited by chelating agents. Bound not removed washing sucrose, respiratory inhibitors, detergents, mercurials, but agents having strong affinity for copper. Some converted on being bound. Iron, once bound, essentially attached an irreversible manner, since it various other additives. However, initial iron sensitive these additives, which suggests that may initially reversible manner. only slightly Ca2+, Sr2+, Mg2+, Mn2+, inhibition increased adding phosphate source energy. Zn2+, Ag+, especially Hg2+, potent inhibitors copper-binding above cations. There no monovalent No competition between iron. In fact, stimulatory iron, Thus, do same locus. insensitive K+ Pi, energy source. Fe2+ cations Li+, Na+, K+. Divalent cations, such Mg2+ 25 40% inhibitory toward at concentrations twice Fe2+. Zn2+ Hg2+ (70 inhibition) divalent It is concluded sites implicated others Zn2+. are different Ca2+.