人类胎盘碱性磷酸酶在胍和脲变性时的活力变化

CHANGES OF CATALYTIC ACTIVITY OF HUMAN PLACENTAL ALKALINE PHOSPHATASE DURING DENATURATION BY GUANIDINIUM CHLORIDE AND UREA

①目的探讨人类胎盘碱性磷酸酶（ＰＡＬＰ）在胍和脲变性时的活力变化，为研究ＰＡＬＰ的分子进化及其作用机制、构象与活力的关系奠定基础。②方法在不同浓度的盐酸胍或脲的存在下，按标准方法测定ＰＡＬＰ在变性终态和变性过程中的活力变化。③结果ＰＡＬＰ在胍变性过程中，盐酸胍浓度在２．０ｍｏｌ／Ｌ之内其活力增加，大于２．０ｍｏｌ／Ｌ时活力降低，５．０ｍｏｌ／Ｌ以上活力丧失；ＰＡＬＰ在胍变性终态时，不同浓度的盐酸胍均抑制其活力。ＰＡＬＰ在脲变性过程中或变性终态时其活力均降低。④结论提示ＰＡＬＰ与其他不同来源的碱性磷酸酶起源相同。

Objective To study the changes of activity of human placental alkaline phosphatase(PALP) during denaturation by guanidinium chloride and urea in order to help understanding the PALP molecular evolution, the mechanism of its action and the relationship between conformation and activity of purified PALP. Method Standard method was used to measure the activity changes of PALP during the process and at the terminal stage of denaturation by different concentrations of guanidinium chloride and urea. Result During denaturation by guanidinium chloride , enhancement of PALP activity was obtained when guanidinium chloride was less than 2.0mol/L. Inhibition of the activity appeared when guanidinium chloride exceeded 2.0mol/L. Finally the PALP activity completelu lost when guanidinium chloride exceeded 5.0mol/L. At the terminal stage of denaturation, any concentrations of guanidinium chloride could inhibit the activity of PALP. The activity of PALP was decreased both during the process and at the termianl stage of denaturation by urea. Conclusion The results suggest PALP and other sources of PALP evolved from a commom ancestral gene, the conformation and mechanism of action is similar.