THE INFLUENCE OF PH ON THE EQUILIBRIUM DISTRIBUTION OF IRON BETWEEN THE METAL-BINDING SITES OF HUMAN TRANSFERRIN
THE INFLUENCE OF PH ON THE EQUILIBRIUM DISTRIBUTION OF IRON BETWEEN THE METAL-BINDING SITES OF HUMAN TRANSFERRIN
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DOI：
10.1042/bj1930717
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发表时间：
1981-01-01
影响因子：
4.1
通讯作者：
WILLIAMS, J
中科院分区：
文献类型：
--
作者：
CHASTEEN, ND;WILLIAMS, J
采用尿素/聚丙烯酰胺凝胶电泳法研究了转铁蛋白与金属离子的结合特性在pH 6-9范围内对pH的依赖性。本文给出了计算铁与转铁蛋白2个位点逐步结合的4个条件位点常数的相对值和计算转铁蛋白4种主要形式（脱铁转铁蛋白、C-末端和N-末端单铁转铁蛋白和二铁转铁蛋白）之间平衡分布的方程。铁的相对亲和力的2个网站和铁结合的协同性遵循特征pH滴定曲线。一个数学模型，可以解释前者的行为。在这两种情况下，金属结合位点都受到具有接近生理pH的表观pKa值的官能团的电离的影响。7.4.从这些基团释放质子时有很强的正协同作用。结果表明，在研究转铁蛋白分子的2个位点的差异性质时，必须精确控制pH。
The dependence of the metal-binding properties of transferrin on pH in the pH 6-9 range was investigated by urea/polyacrylamide-gel electrophoresis. Equations are presented for calculating the relative values of the 4 conditional site constants for the stepwise binding of Fe to the 2 sites of transferrin and for calculating the equilibrium distribution of the protein among the 4 principal forms, apotransferrin, the C-terminal and N-terminal monoferric transferrins and diferric transferrin. The relative affinity of iron for the 2 sites and the co-operativity of Fe-binding follow characteristic pH titration curves. A mathematical model that can account for the former behavior is presented. In both cases the metal-binding sites are affected by the ionization of functional groups with apparent pKa values near physiological pH .apprx. 7.4. There is strong positive co-operativity in the release of protons from these groups. The results indicate that pH must be accurately controlled in studies of the differential properties of the 2 sites of the transferrin molecule.