An X-ray absorption study of the reconstitution process of bovine Cu,Zn superoxide dismutase by Cu(I)-glutathione complex.

The Cu(I)GSH complex has recently been shown to be a good candidate for delivering copper to the active site of Cu-free Cu,Zn superoxide dismutase both in vivo and in vitro. In this work X-ray absorption spectroscopy has been used to characterize the Cu(I)GSH complex and to follow in vitro the reconstitution of Cu,Zn superoxide dismutase from the copper-free protein and this complex. The results obtained indicate that the copper is directly transferred as Cu(I) from the GSH complex into the empty copper binding site. No evidence has been obtained for a ternary complex in which the metal is bound to both GSH and the protein.