卫生研究

为研究金属硫蛋白与铅的相互作用 ,从基因工程菌 (BL2 1菌 )中分别提取并纯化结合了镉的金属硫蛋白α和β结构域 ,用酸解的方法脱去蛋白中的金属镉 ,然后用Sephadex G2 5纯化分别得到脱金属的α和 β结构域硫蛋白 (apo α MT和apo β MT)。在apo α MT和apo β MT中分别加入不同比例的铅 ,待反应完全后 ,用紫外吸收光谱法研究它们的巯基金属簇结构。经紫外吸收光谱图研究证明 :α结构域与铅反应可产生两种形式的结合物 ,一种为结合 4个铅的MT(Pb4 α MT) ,另一种则为结合 7个铅的MT(Pb7 α MT) ,而 β结构域与铅反应仅生成一种结合 3个铅的产物 (Pb3 β MT)。同时 ,通过与DTNB反应测定了它们的速率常数 ,结果表明结合了 4个铅的α结构域比另外两个产物的稳定性好。该研究对进一步探讨金属硫蛋白与铅反应的机理及其排铅功能提供了有力的证据。

For studying the actions of metallothionein(MT) binding to lead, the α and β structural domain of metallothionein binding to Cd (Cd 7 α MT and Cd 7 β MT)was extracted and purified from a strain of BL2I by dissolving them in acid to eliminate protein. The apo α MT and apo β MT were separated by gel Sephadex G25 to eliminate Cd. Different doses of lead were added to the apo α MT and apo β MT. The structure of MT metal Cluster with lead was formed after reacting completely, and was then examined by ultraviolet spectrophotometer. The UV spectrum showed that the interaction of lead withαdomain leading to two kind of products, one binding with 4 lead(Pb 4 α MT)and the other binding with 7 lead(Pb 7 α MT). Only one product, the βdomain binding with 3 lead(Pb 3 β MT)was formed. The reaction rate of these products with DTNB was also measured in this study. Results showed that the domain binding to 4 lead was more stable than the others. All these works provide strong evidence that further studies on the mechanism of MT interacting with lead and the function of MT in eliminating lead were needed.