Transfer of copper and zinc from ionic and metallothionein-bound forms to Cu, Zn--superoxide dismutase.
Reactivity in transfer of copper (Cu) and zinc (Zn) to their binding sites of superoxide dismutase (SOD) was examined in vitro by the HPLC/atomic absorption spectrophotometry. Ionic Cu (cuprous and cupric ions) were incorporated more efficiently than the metal bound to metallothionein. Cu binds not only to the Cu-binding site but also to the Zn-binding site. Although Zn in the reaction medium and the metal bound to the Zn-binding site of SOD affected little the reactivity in binding of ionic Cu, they disturbed the reactivity of Cu bound to metallothionein to the Cu-binding site. Both ionic and metallothionein-bound Zn were transferred at a comparable efficiency to the Zn-binding site but not to the Cu-binding site. Co-existing ionic Cu but not metallothionein-bound Cu in the medium inhibited the binding of Zn to SOD. The results indicate that ionic Cu can be transferred to both Cu- and Zn-binding sites of SOD more efficiently than metallothionein-bound Cu, while both ionic and metallothionein-bound Zn are transferred only to Zn-binding site at a comparable efficiency.
Suzuki
K T
KT
Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Kuroda
T
T
D000818:Animals; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000378:metabolism*; D007477:Ions; D008668:Metallothionein / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013054:Spectrophotometry, Atomic; D013482:Superoxide Dismutase / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
D007477:Ions; D003300:Copper; D008668:Metallothionein; D013482:Superoxide Dismutase; D015032:Zinc