EFFECT OF MG2+ AND SPERMINE ON KINETICS OF CA2+ TRANSPORT IN RAT-LIVER MITOCHONDRIA
EFFECT OF MG2+ AND SPERMINE ON KINETICS OF CA2+ TRANSPORT IN RAT-LIVER MITOCHONDRIA
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DOI：
10.1007/bf00745043
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发表时间：
1977-01-01
影响因子：
3
通讯作者：
AKERMAN, KEO
中科院分区：
文献类型：
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作者：
AKERMAN, KEO
在蔗糖或氯化钾介质中，在2.5-100µm的钙浓度范围内，线粒体钙离子初始转运速率与钙离子浓度的关系曲线(动力学曲线)呈双曲线形状。在镁离子或多胺精胺的存在下，它们是钙离子与膜表面低亲和力结合的竞争性抑制剂，曲线图的形状变成了S形。当这些试剂的浓度较高时，在蔗糖介质中测得线性动力学曲线。在KCl介质中，随着镁离子浓度或精胺浓度的增加，动力学曲线的S型曲线增强。镁离子和精胺可能通过干扰钙离子与膜表面低亲和力部位的结合而影响钙离子转运动力学，而钙离子与这些部位的结合可能是线粒体钙离子转运的第一步。
Plots relating the initial rate of mitochondrial Ca2+ transport to the Ca2+ concentration (kinetic plots) have a hyperbolic shape in a Ca2+ concentration range of 2.5-100 .mu.M as measured in sucrose or KCl media. In the presence of Mg2+ or a polyamine spermine, which are competitive inhibitors of Ca2+ binding to low affinity sites at the membrane surface, the shape of the plots becomes sigmoidal. At higher concentrations of these agents linear kinetic plots were obtained as measured in a sucrose medium. In a KCl medium the sigmoidality of the kinetic plots was enhanced by an increase in the Mg2+ or spermine concentration. Mg2+ and spermine may affect the kinetics of Ca2+ transport by interfering with Ca2+ binding to low affinity sites of the membrane surface and the binding of Ca2+ to these sites was probably the first step of the mitochondrial Ca2+ transport.