心脏肌膜的钙结合及ATP酶活性

Calcium binding and ATPase activities of heart sarcolemma.

作者信息

Dhalla N S, Anand M B, Harrow J A

出版信息

J Biochem. 1976 Jun;79(6):1345-50. doi: 10.1093/oxfordjournals.jbchem.a131188.

DOI:10.1093/oxfordjournals.jbchem.a131188

Abstract

Rat heart sarcolemma prepared by the hypotonic shock-LiBr treatment method was found to bind calcium by a concentration-dependent and saturable process. The calcium binding values at 50 muM and 1.25 mM Ca2+ concentrations were about 30 and 250 nmoles/mg protein, respectively. Both Mg2+ and ATP inhibited calcium binding and no evidence for energy-linked calcium binding with sarcolemmn was found. z sn the other hand, maximal ATP hydrolysis by heart sarcolemma was seen at 4 mM Mg2+ or Ca2+. The Ca2+-ATPase LEO) of Ca2+ failed to stimulate ATP hydrolysis in the presence of various concentrations of Mg-ATP. These results indicate the absence of a "calcium pump" mechanism in the heart sarcolemmal membrane preparation employed in this study.

摘要

通过低渗休克-LiBr处理方法制备的大鼠心脏肌膜，被发现能通过一个浓度依赖性和可饱和的过程结合钙。在50μM和1.25 mM Ca2+浓度下的钙结合值分别约为30和250纳摩尔/毫克蛋白质。Mg2+和ATP均抑制钙结合，且未发现与肌膜有能量关联的钙结合的证据。另一方面，心脏肌膜的最大ATP水解在4 mM Mg2+或Ca2+时出现。在存在各种浓度的Mg-ATP时，Ca2+的Ca2+-ATPase（LEO）未能刺激ATP水解。这些结果表明，在本研究中使用的心脏肌膜制备物中不存在“钙泵”机制。