Masuoka J, Saltman P
Department of Biology, University of California at San Diego, La Jolla 92093-0322.
J Biol Chem. 1994 Oct 14;269(41):25557-61.
Metal binding strategies employing low molecular weight chelators and equilibrium dialysis were used to investigate several unresolved aspects of zinc and copper binding to serum albumin. Direct measurement of histidine binding to bovine serum albumin when the histidine is presented either as a metal-chelate or alone provides no evidence for an albumin-metal-histidine ternary complex. Using previously determined intrinsic constants for Zn(II) and Cu(II), we have measured zinc binding to bovine serum albumin in the presence of saturating amounts of copper. The results of these experiments unambiguously show that zinc and copper bind at separate noninteracting sites on this protein. The intrinsic constants for zinc and copper binding to dog serum albumin have been determined. Contrary to previous reports, we find that dog serum albumin has a specific high affinity site for copper, log10K 10.17 for Cu(II) compared to 6.85 for Zn(II) at the separate site.
采用低分子量螯合剂和平衡透析的金属结合策略，用于研究锌和铜与血清白蛋白结合的几个未解决的方面。当组氨酸以金属螯合物形式或单独存在时，直接测量其与牛血清白蛋白的结合，未发现白蛋白 - 金属 - 组氨酸三元复合物的证据。利用先前测定的锌（II）和铜（II）的固有常数，我们在存在饱和量铜的情况下测量了锌与牛血清白蛋白的结合。这些实验结果明确表明，锌和铜结合在该蛋白质上不同的非相互作用位点。已测定了锌和铜与犬血清白蛋白结合的固有常数。与先前的报道相反，我们发现犬血清白蛋白对铜有一个特定的高亲和力位点，铜（II）的log10K为10.17，而在另一个位点锌（II）的log10K为6.85。
