摘要
本试验对重金属离子Ｃｄ２＋、Ｐｂ２＋替代Ｃａ２＋而活化肌钙蛋白Ｃ（ＴｎＣ）的有效性进行了研究，取得如下结果：①与Ｃａ２＋相似，Ｃｄ２＋、Ｐｂ２＋可有效诱导ＴｎＣ的构象改变，包括其疏水部位暴在及在聚丙烯酰胺凝胶上的电泳迁移率改变。②Ｃｄ２＋、Ｐｂ２＋对天然肌动蛋白ＡＴＰ酶活性的影响呈现出双相效应，低浓度时刺激，其最大刺激活性分别可达到８６％和９２％，半刺激浓度（ＡＣ５０）均为３０μｍｏｌ／Ｌ，而高浓度时则抑制该酶活性，半抑制浓度（ＩＣ５０）分别为６５０μｍｏｌ／Ｌ和７８０μｍｏｌ／Ｌ。③Ｃｄ２＋、Ｐｂ２＋仅对已脱去ＴｎＣ的脱敏肌动球蛋白ＡＴＰ酶表现抑制效应，１Ｃ５０分别为５１０μｍｏｌ／Ｌ和５２０μｏｌ／Ｌ，上述结果表明，Ｃｄ２＋、Ｐｂ２＋可有效地替代Ｃａ２＋而活化ＴｎＣ，提示重金属离子在体内的部分毒性作用也经由ＴｎＣ而介导。
The effect of heavy metal cations Cd2+ and Pb2+ substituting for Ca2+ on activatetroponin C(TnC )was studied and the following results were obtained:( 1 ) Cd2+ and Pb2+ caninduce the conformational changes of TnC free of calcium, including the exposure of hydrophobicsites and the change of mobility on polyacrylamide gel electrophoresis.2)Cd2+and Pb2+ affectednative actomyosin ATPase biphasically:activating the ATPase at low concentration,with themaximal activity of 86%and 92%, respectively,and the both AC50 of 30μmol/L,respectively,inhibiting the ATPase at high concentration with IC50 of 650μmol/L and 780 μmol/L,respec-tively.(3)Cd2+and Pb2+ showed inhibitory effect only on desensitized actomyosin ATPase(freeof TnC) with IC50 of 510μmol/L and 520μmol/L,respectively.The above results suggest thatCd2+ and Pb2+ can induce the conformational change of TnC and activate the ATPase regulated byTnC, indicated that some heavy metalions toxicity to biological system may be mediated throughthe TnC modulating。
出处
《广东药学院学报》
CAS
1995年第4期216-219,227,共5页
Academic Journal of Guangdong College of Pharmacy
关键词
镉离子
铅离子
肌钙蛋白C
钙调素
troponin C
heavy metal toxicity
cadmium ion
Iead ion
calmodulin
acto-myosin ATPase
