铝(Ⅲ)与脱铁伴清蛋白结合的紫外差光谱研究

在 pH7.4、 0.1mol· L~(－1)N-2-羟乙基哌嗪- N′-2-乙磺酸（ Hepes）及室温条件下，使用紫外吸收差光谱进行了铝(Ⅲ)对脱铁伴清蛋白的滴定。结果表明铝(Ⅲ)与脱铁伴清蛋白结合后其紫外差光谱在 238nm和 291nm处出现吸收峰。在 238nm处铝(Ⅲ)-脱铁伴清蛋白配合物的摩尔吸光系数是 (1.52± 0.04)× 10~4cm~(－1)· mol~(－1)· L。铝(Ⅲ)可占据脱铁伴清蛋白的两个金属离子结合部位，条件稳定常数是 lgK_N=11.21± 0.12,lgKC=9.53± 0.24。 N-端单铁伴清蛋白的紫外差光谱滴定表明，铝 ?优先占据脱铁伴清蛋白的 N端结合部位。

UV Difference Spectra Study on the Binding of Aluminum Ions with Apoovotransferrin

The binding of aluminum ions to apoovotransferrin has been studied by means of UV difference spectra. Aluminum binding produces peaks at 238nm and 291nm that characteristic of binding at the apoovotransferrin specific metal binding sites. The molar absorptivity of aluminum ions to apoovotransferrin complex at 238nm is (1.52± 0.04)× 10⁴cm^-1· mol^-1· L. Conditional stability constants, which are (11.21± 0.12) and 9.53± 0.24 for lgK₁ and lgK₂ respectively, fot the complexes of aluminum ions to apoovotransferrin in 0.1mol· L^-1 Hepes, pH7.4, room temperature and air saturated are measured. The titration of N-terminal monoferric ovotransferrin with aluminum ions indicates that the larger K₁ value is associated primarily with Al binding at the Nterminal site and the smaller K₂ value is associated primarily with the C-terminal site.