利用放射性核素示踪技术对镉及铬与毛发结合机制的研究

Study of Binding Mechanism between Endogenous and Exogenous Cadmium and Chromium with Hair by Means of Radioactive Isotope Labelling

目的 利用放射性核素示踪方法研究内外源性镉、铬与毛发结合的机制,从分子水平探讨目前常用的头发预处理方法能否有选择地清除外源性而保留毛发中内源性镉、铬的含量。方法 提取含有内源性的放射性核素镉、铬的大白鼠鼠毛及外源性放射性核素镉、铬的人发蛋白质,利用柱层析将毛发蛋白质分组,分别测定不同蛋白组分中的放射性镉、铬的活度来确定与镉、铬相互结合的毛发蛋白组分。比较与内外源性镉、铬相结合的蛋白组分来分析核素与毛发结合机制。结果 内外源性镉、铬核素均以与毛发蛋白质相互结合的方式存在于毛发中,而且所结合的蛋白质组分的相对分子量相同。IAEA法和海鸥洗涤剂对内外源性的镉、铬有轻度地洗脱,但EDTANa_2和稀硝酸溶液对两种核素有强力的清除效力。结论 由于内外源性镉、铬核素与毛发蛋白质结合的相似性,实验中头发样品的预处理方法在清除外源性核素的同时,在一定程度上也影响头发内源性的核素的含量。

Objective To study potential binding mechanism of endogenous and exogenous cadmium and chromium to hair by means of radioactive isotope labeling in order to diccuss, at molecular level, whether or not routine hair pretreatments could selectively remove exogenous 115mCd and 51Cr, and retain the endogenous elements. Methods The proteins of mouse hair labeled by endogenous 115mCd and 51Cr, and human scalp hair labeled by exogenous 115mCd and 51 Cr was extracted.Then we separate the proteins by means of Sephadex- G75 column chromatography based on the molecular weights of different protein components.The radioactive intensity of 115mCd and 51Cr in different components of the proteins was measured to determine the protein component that binds with 115mCd and 51Cr. Results Both endogenous and exogenous 115mCd and 51Cr seemed to share similar binding mechanisms to hair, Therefore, it is very difficult to selectively remove exogenous 115mCd and 51Cr, and to retain the endogenous elements by any hair analysis pretreatments. Conclusions Those commonly used hair- washing methods can remove exogenous cadmium and chromium, and at the same time, remove the endogenous element as well.