Aoyagi Y, Ikenaka T, Ichida F
Cancer Res. 1979 Sep;39(9):3571-4.
The bilirubin-binding ability of human alpha-fetoproteins, which were purified from fetal cord serum and from ascites fluid of a hepatoma-bearing patient, was examined by the difference spectrum and the Jacobsen peroxidase methods. The difference spectrum observed as a result of the specific binding of bilirubin to alpha-fetoprotein had a maximum at 482 nm, and this pattern was quite similar to that observed for serum albumin. The result obtained by the difference spectrum method showed that 1 mol of each alpha-fetoprotein bound 1 mol of bilirubin at pH 8.3 and that the dissociation constants of the complexes of bilirubin with fetal alpha-fetoprotein and hepatoma-derived alpha-fetoprotein were 2.6 x 10(-7) and 5.0 x 10(-7) M, respectively. The Jacobsen enzymatic method using horseradish peroxidase gave the same values for molar binding ratios and similar dissociation constants, 7.1 x 10(-7) M for fetal alpha-fetoprotein and 7.4 x 10(-7) M for hepatoma-derived alpha-fetoprotein. These results indicate that alpha-fetoprotein may function as a carrier protein for bilirubin as has been shown for serum albumin.
采用差示光谱法和雅各布森过氧化物酶法，对从胎儿脐带血清和肝癌患者腹水液中纯化得到的人甲胎蛋白的胆红素结合能力进行了检测。胆红素与甲胎蛋白特异性结合所观察到的差示光谱在482nm处有一个最大值，这种模式与血清白蛋白所观察到的非常相似。差示光谱法得到的结果表明，在pH8.3时，每摩尔甲胎蛋白结合1摩尔胆红素，胆红素与胎儿甲胎蛋白和肝癌来源甲胎蛋白复合物的解离常数分别为2.6×10⁻⁷和5.0×10⁻⁷M。使用辣根过氧化物酶的雅各布森酶法得到的摩尔结合比相同，解离常数相似，胎儿甲胎蛋白为7.1×10⁻⁷M，肝癌来源甲胎蛋白为7.4×10⁻⁷M。这些结果表明，甲胎蛋白可能像血清白蛋白一样作为胆红素的载体蛋白发挥作用。
