摘要：Cd-binding proteins were purified from the bone of male rats injected with CdCl2 for 21 days. The femur was excised and lyophilized after removal of the marrow and extranious tissue. The cancellous bone (epiphysis and metaphysis) was obtained from the femur, ground to fine powder, and used for the analysis of metal such as Cu and Cd and Cd-binding proteins. The cancellous bone powder was suspended in Tris-HCl (pH 8.0) and centrifuged at 105000×g. The supernatant fraction was sequentially applied to columns on Sephadex G-75, Bio-Gel P-10 and DEAE Sephadex A-25. Two Cd-binding proteins were purified. Cd, Cu contents and amino acid composition of Cd-binding proteins were examined. Both purified Cd-binding proteins contained 3-4μg Cd/mg protein, 8-9μg Cu/mg protein, and 2-4 mol % cysteine residue. UV absorption spectra of both Cd-binding proteins were different from those of metallothioneins. These results showed that Cd-binding proteins were different from hepatic metallothioneins. From the experiments by the use of normal rat, it is indicated that there might exist some proteins corresponding to Cd-binding proteins.
关键词：purification;Cd-binding proteins;bone of rat;Cd, Cu contents, amino acid composition
