稀土离子对CaM及Ca^(2+)-Mg^(2+)-ATPase活力及CD研究

STUDIES OF THE EFFECTS OF RARE EARTH IONS ON THE ACTIVITYAND CD OF Ca2+-Mg2+-ATPase STIMULATED BY CALMODULIN

研究了稀土离子（Ｌｎ３＋）对钙调蛋白（ＣａＭ）调控的Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ的活力影响。结果表明，在ＣａＭ和Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ的体系中，一些Ｌｎ３＋（Ｌａ３＋、Ｇｄ３＋）对由ＣａＭ调节的Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ的活力影响呈现双相效应，即Ｌｎ３＋在低浓度时，能提高激活Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ的水解活力；在高浓度时，则抑制ＣａＭ调节Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ活力的能力；少数Ｌｎ３＋（Ｓｍ３＋）仅表现出抑制效应。在无ＣａＭ的Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ体系中，高浓度的Ｌｎ３＋抑制Ｃａ２＋－Ｍｇ２＋－ＡＴＰａｓｅ的基础活力。结合圆二色（ＣＤ）谱信息对Ｌｎ３＋和ＣａＭ相互作用的分子机制进行了初步的探讨。

The effects of rare earth ions (Ln3+) on the activity of Ca2+-Mg2+-ATPase stimulated by calmodulin (CaM) have been studied. The results revealed that the curve of Ca2+-Mg2+-ATPase activity stimulated by CaM in different Ln3+ concentration is apparently biphase. Ln3+ can activate CaM at low concentration, but they have inhibitive function at high concentration. Some Ln3+(Sm3+) only shows inhibitive effect. In the absence of CaM, Ln3+ inhibits the basic activity of Ca2+-Mg2+-ATPase at high concentration. The molecular mechanism of interaction between Ln3+ and CaM has been studied primarily by CD spectroscopy.