BINDING OF LEAD TO A METALLOTHIONEIN-LIKE PROTEIN IN HUMAN ERYTHROCYTES

被引:42
作者
CHURCH, HJ
DAY, JP
BRAITHWAITE, RA
BROWN, SS
机构
[1] UNIV MANCHESTER, DEPT CHEM, MANCHESTER M13 9PL, LANCS, ENGLAND
[2] DUDLEY RD GEN HOSP, REG LAB TOXICOL, BIRMINGHAM B18 7QH, W MIDLANDS, ENGLAND
关键词
D O I
10.1016/0162-0134(93)80048-E
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
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.
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页码:55 / 68
页数:14
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