Selenium protection against mercury toxicity: high binding affinity of methylmercury by selenium-containing ligands in comparison with sulfur-containing ligands

Yukio Sugiura, Yoichi Tamai, Hisashi Tanaka
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引用次数: 79

Abstract

In determining the protection of selenium against mercury toxicity, the binding affinity of methylmercury by various selenium-containing ligands was investigated by proton magnetic resonance (PMR) spectroscopy. The most striking feature was the small J199Hg-1H value of the selenocysteamine- and selenocysteine-methylmercury complexes, namely, the high affinity of the selenohydryl group to the mercury in comparison with those of the sulfhydryl and amino groups. The order of binding affinity of the coordination groups toward methylmercury is clearly SeH > SH ⩾ Se-Se > NH2 > S-S, SeCH3, SCH3. A definite correlation was found to exist between the mercury-proton coupling constants and the chemical shifts of methyl groups of the methylmercury complexes. A relationship betwen the order (Se > S > NH2) of affinity for methylmercury and the basicity (or electronegativity and covalent radius) of the donor groups was also discussed. These results suggest the high covalency of the CH3Hg-Se bond, which involves dπ-dπ back bonding.

硒对汞毒性的保护作用:与含硫配体相比,含硒配体对甲基汞的结合亲和力高
为了确定硒对汞的保护作用,采用质子磁共振(PMR)技术研究了不同含硒配体对甲基汞的结合亲和力。最显著的特征是硒半胱胺-和硒半胱胺-甲基汞配合物的J199Hg-1H值较小,即硒羟基与巯基和氨基相比对汞具有较高的亲和力。配位基对甲基汞的结合亲合力顺序明显为SeH >SH小于Se-Se >氨基比;S-S, SeCH3, SCH3。发现汞-质子偶联常数与甲基汞配合物中甲基的化学位移之间存在一定的相关性。顺序(Se >年代比;还讨论了甲基汞的亲和性(NH2)和给体基团的碱度(或电负性和共价半径)。这些结果表明CH3Hg-Se键具有较高的共价,其中包含dπ-dπ回键。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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