BINDING OF LEAD TO A METALLOTHIONEIN-LIKE PROTEIN IN HUMAN ERYTHROCYTES
BINDING OF LEAD TO A METALLOTHIONEIN-LIKE PROTEIN IN HUMAN ERYTHROCYTES
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DOI：
10.1016/0162-0134(93)80048-e
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发表时间：
1993-01-01
影响因子：
3.9
通讯作者：
BROWN, SS
中科院分区：
文献类型：
--
作者：
CHURCH, HJ;DAY, JP;BROWN, SS
我们研究了24名职业接触无机铅的工人的红细胞，一名无症状的铅工人表现出异常高的接触，和8名对照组（血铅分别为300-750，1800和< 100 μ g/L）。高效蛋白质色谱、电泳和微量金属分析已经确定了一种低分子量，铜和含锌蛋白质。这种蛋白质（命名为蛋白质M）在体外与缓冲硝酸铅孵育时结合铅。发现蛋白M的纯化样品显示出与金属硫蛋白（M.Wt.几乎等于6500，低pI，和在254 nm处更大的UV吸光度）。氨基酸分析发现33%的半胱氨酸的组成，但没有芳香族氨基酸。高度暴露的受试者显示内源性铅与蛋白质M结合，通过离子交换进一步纯化后发现其与一种特定成分（蛋白质M5）相关。蛋白质M5在对照组中的含量要低得多。这些发现表明，红细胞中存在一种金属硫蛋白样蛋白，它与铅结合，将其隔离成一种非生物可利用的形式，从而防止铅中毒。
We have studied the erythrocytes from 24 workers occupationally exposed to inorganic lead, one asymptomatic lead worker showing exceptionally high exposure, and eight control subjects (blood lead 300-750, 1800, and < 100 mug/L, respectively). High performance protein chromatography, electrophoresis, and trace metal analysis have identified a low M.Wt., copper, and zinc-containing protein in all cases. This protein (designated protein M) bound lead on in vitro incubation with buffered lead nitrate. Purified samples of protein M were found to show characteristics consistent with metallothionein (M.Wt. almost-equal-to 6500, low pI, and greater UV absorbance at 254 nm). Amino acid analysis found a composition of 33% cysteine but no aromatic amino acids. The highly exposed subject showed endogenous lead binding to protein M, which on further purification by ion exchange was found to be associated with one particular constituent (protein M5). Protein M5 was present in much lower quantities in control subjects. These findings suggest the existence of a metallothionein-like protein in erythrocytes which binds lead, sequestering it into a nonbioavailable form and hence protects against lead toxicity.