Taleva B, Maneva A, Sirakov L
Department of Biochemistry, Medical University of Sofia, Medical Faculty, Bulgaria.
Biol Trace Elem Res. 1999 Apr;68(1):13-24. doi: 10.1007/BF02784393.
The effect of metal ions at a concentration of 10(-8) to 10(-5) M [using their salts: ZnCl2, CdCl2, LiCl, CuSO4, NiSO4, Al2(SO4)3, (NH4)2MoO4 on the lactoferrin (Lf) binding to the erythrocyte membrane receptors was studied. In the absence of metal ions, Scatchard's analysis showed the existence of two kinds of binding site: one with high affinity and low capacity, and the another with low affinity and high capacity. All these metals, excluding Zn2+ and Cd2+, at a concentration 10(-5) M decreased the affinity of Lf binding (Ka1) to the high-affinity receptors. In the presence of Zn2+ and Cd2+, only the low-affinity binding site was found. Significant inhibition on the affinity (Ka2) of the low-affinity class of receptors showed Zn2+, Al3+, and Mo6+. Depending on their concentration (10(-8)-10(-5) M), these ions enhanced to a different extent, the binding capacity of the both types receptors, but the effect did not correspond to the applied doses. Several explanations of the mechanism for influence of the metal ions on the Lf-receptor interaction is discussed.
研究了浓度为10⁻⁸至10⁻⁵ M的金属离子[使用它们的盐：ZnCl₂、CdCl₂、LiCl、CuSO₄、NiSO₄、Al₂(SO₄)₃、(NH₄)₂MoO₄]对乳铁蛋白（Lf）与红细胞膜受体结合的影响。在没有金属离子的情况下，Scatchard分析表明存在两种结合位点：一种具有高亲和力和低容量，另一种具有低亲和力和高容量。除Zn²⁺和Cd²⁺外，所有这些浓度为10⁻⁵ M的金属都会降低Lf与高亲和力受体结合的亲和力（Ka1）。在Zn²⁺和Cd²⁺存在的情况下，只发现了低亲和力结合位点。Zn²⁺、Al³⁺和Mo⁶⁺对低亲和力受体类别的亲和力（Ka2）有显著抑制作用。根据它们的浓度（10⁻⁸ - 10⁻⁵ M），这些离子在不同程度上增强了两种类型受体的结合能力，但这种作用与所施加的剂量不对应。讨论了金属离子对Lf-受体相互作用影响机制的几种解释。
