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目的： 研究汞和铅对人胎盘耐热性碱性磷酸酶（ ＨＰＡＰ） 的作用，以探讨汞和铅影响胎儿发育的分子机制。方法：应用分光光度法分别测定不同浓度氯化汞（ ＨｇＣｌ２） 和硝酸铅［Ｐｂ（ＮＯ３）２］ 存在下的ＨＰＡＰ 活力，用荧光法检测其荧光光谱的变化；用双倒数作图法确定ＨｇＣｌ２ 和Ｐｂ（ ＮＯ３）２ 的抑制类型。结果：ＨｇＣｌ２ 和Ｐｂ（ ＮＯ３）２ 均抑制了ＨＰＡＰ 的活力，并使其荧光强度和发射峰位发生了明显改变，但其作用机制不同。ＨｇＣｌ２ 是ＨＰＡＰ 的混合性抑制剂，其抑制常数为３ ．６０ｍ ｍｏｌＬ；而Ｐｂ（ＮＯ３）２ 是ＨＰＡＰ 的反竞争性抑制剂，其抑制常数为１ ．４０ ｍ ｍｏｌＬ。结论：ＨｇＣｌ２ 和Ｐｂ（ＮＯ３）２ 抑制ＨＰＡＰ 的活力，并使其构象发生改变，这可能是汞和铅影响胎儿发育的重要分子机制之一
Objective: To study the effect of mercury and lead on human placental heat-resistant alkaline phosphatase (HPAP) to explore the molecular mechanism of mercury and lead affecting fetal development. Methods: HPAP activity in the presence of different concentrations of mercury chloride (HgCl2) and lead nitrate [Pb (NO3) 2] was determined by spectrophotometry. Fluorescence was used to detect the changes of fluorescence intensity. HgCl2 And the type of inhibition of Pb (NO3) 2. Results: Both HgCl2 and Pb (NO3) 2 inhibited the activity of HPAP and markedly changed the fluorescence intensity and emission peak, but the mechanism of action was different. HgCl2 is a mixed inhibitor of HPAP with an inhibition constant of 3. 60m molL, while Pb (NO3) 2 is an anti-competitive inhibitor of HPAP with an inhibition constant of 1. 40 m molL. CONCLUSION: HgCl2 and Pb (NO3) 2 inhibit HPAP activity and conformational changes, which may be one of the important molecular mechanisms that lead to mercury and lead affect fetal development