Petering D H, Krezoski S, Villalobos J, Shaw C F, Otvos J D
Department of Chemistry, University of Wisconsin-Milwaukee 53201.
Experientia Suppl. 1987;52:573-80. doi: 10.1007/978-3-0348-6784-9_59.
Zinc and Cadmium metabolism in cultured Ehrlich cells has been studied. Under conditions of restriction of extracellular zinc by EDTA or chelex, zinc in basal Zn-metallothionein (Mt) is transferred from metallothionein to other sites with a rate constant of 0.35 hr-1. Current studies indicate that the rate constant for biodegradation of Mt protein is 0.07-0.11 hr-1, implying that Zn leaves the protein faster than it is biodegraded. After a 30 minute exposure of cells to 17 ng atoms Cd/mg cell protein, Cd initially displaces Zn from Mt and binds to high molecular weight species. Cell proliferation is markedly slowed, although the cells remain viable. Over time Cd shifts into newly synthesized Mt. This protein is made with an apparent rate constant four times that for basal Zn-Mt. The product contains equal amounts of Cd and Zn. However, cell proliferation is not restored for many hours after Cd is sequestered in Mt.
对培养的艾氏腹水癌细胞中的锌和镉代谢进行了研究。在通过EDTA或螯合树脂限制细胞外锌的条件下，基础锌金属硫蛋白（Mt）中的锌以0.35小时⁻¹的速率常数从金属硫蛋白转移到其他位点。目前的研究表明，Mt蛋白的生物降解速率常数为0.07 - 0.11小时⁻¹，这意味着锌离开该蛋白的速度比其生物降解速度更快。细胞暴露于17 ng原子镉/毫克细胞蛋白30分钟后，镉最初从Mt中取代锌并与高分子量物质结合。细胞增殖明显减缓，尽管细胞仍保持活力。随着时间的推移，镉转移到新合成的Mt中。这种蛋白的合成表观速率常数是基础锌-Mt的四倍。该产物含有等量的镉和锌。然而，在镉被隔离在Mt中许多小时后，细胞增殖仍未恢复。
