Aoyagi Y, Ikenaka T, Ichida F
Cancer Res. 1978 Oct;38(10):3483-6.
The copper(II)-binding ability of human alpha-fetoproteins, which were purified from umbilical cord serum and from ascites fluid of a hepatoma-bearing patient, was examined by equilibrium dialysis and gel filtration methods. The pH dependence of the copper(II)-binding ability of alpha-fetoprotein was quite similar to that of albumin. Alpha-fetoprotein bound 1 mol of copper(II) ion per mol of protein above pH 6.0 and 0.5 mol of copper(II) ion at pH 5.4, which is close to the pK value of the imidazole group of histidine. Photooxidation of alpha-fetoprotein in the presence of methylene blue resulted in the loss of the copper(II)-binding ability of the protein in parallel with the destruction of the histidyl residues. A synthetic amino-terminal undecapeptide of alpha-fetoprotein also bound copper(II) ion. These results indicate that the histidyl residue at the amino-terminal region of alpha-fetoprotein plays an important role in the copper(II)-binding ability of the protein.
采用平衡透析和凝胶过滤法，检测了从脐带血清和肝癌患者腹水液中纯化得到的人甲胎蛋白结合铜（II）的能力。甲胎蛋白结合铜（II）能力的pH依赖性与白蛋白十分相似。在pH 6.0以上时，每摩尔甲胎蛋白结合1摩尔铜（II）离子，在pH 5.4时结合0.5摩尔铜（II）离子，此pH接近组氨酸咪唑基的pK值。在亚甲蓝存在的情况下，甲胎蛋白的光氧化作用导致该蛋白结合铜（II）的能力丧失，同时组氨酸残基遭到破坏。甲胎蛋白的合成氨基末端十一肽也能结合铜（II）离子。这些结果表明，甲胎蛋白氨基末端区域的组氨酸残基在该蛋白结合铜（II）的能力方面发挥着重要作用。
