The Ca2+-ATPase partial reactions in cardiac and skeletal sarcoplasmic reticulum. A comparison of transient state kinetic data.
The Ca2+-ATPase partial reactions in cardiac and skeletal sarcoplasmic reticulum. A comparison of transient state kinetic data.
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Ca2-ATP酶在心脏和骨骼肌浆网中的部分反应。
DOI：
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发表时间：
1980
影响因子：
4.8
通讯作者：
J. Froehlich
中科院分区：
文献类型：
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作者：
M. Sumida;T. Wang;A. Schwartz;C. Younkin;J. Froehlich
通过快速混合酸淬灭技术，在 21°C 下研究了犬和兔心肌肌浆网 (SR) 的 Ca2+-ATP 酶反应动力学，并与快速骨骼肌制剂获得的数据进行了比较。在一系列 Ca2+（2 至 14 p~）和 ATP（10 至 100 p~）浓度范围内，来自心脏 SR 的膜囊泡被 ATP 磷酸化，其半衰期接近于与骨骼 SR 中发现的最大磷酸酶水平相似。磷酸酶形成的时间过程表现出短暂的超调，这在犬和兔心脏 SR 中比在兔骨骼 SR 中更明显。在 ATP 磷酸化和 EGTA 存在下去磷酸化后，两种类型的 SR 中均检测到快速和缓慢水解的磷酸酶。磷酸酶的初始衰变显示出单相行为，并且在犬和兔心脏 SR 中以相似的速率发生，而在兔骨骼 SR 中，磷酸酶消失得更快，并显示出早期的双相模式。这些观察结果虽然有利于心脏和骨骼 SR 的相似磷酸化机制，但表明参与磷酸酶分解的反应途径或反应速率可能存在差异。
The kinetics of the reactions of the Ca2+-ATPase of sarcoplasmic reticulum (SR) from canine and rabbit cardiac muscle were investigated at 21°C by means of a rapid mixing acid-quench technique and compared with data obtained from fast skeletal muscle preparations. Over a range of Ca2+ (2 to 14 p ~ ) and ATP (10 to 100 p ~ ) concentrations, membrane vesicles from cardiac SR were phosphorylated by ATP with half-times for approach to maximal phosphoenzyme levels similar to those found in skeletal SR. The time course of phosphoenzyme formation displayed a transient overshoot, which was more pronounced in canine and rabbit cardiac SR than in rabbit skeletal SR. Rapidly and slowly hydrolyzing phosphoenzymes were detected in both types of SR following phosphorylation by ATP and dephosphorylation in the presence of EGTA. The initial decay of the phosphoenzyme shows monophasic behavior and occurs at similar rates in canine and rabbit cardiac SR, whereas in rabbit skeletal SR the phosphoenzyme disappears more rapidly and shows an early biphasic pattern. These observations, while favoring similar phosphorylation mechanisms for cardiac and skeletal SR, indicate possible differences in the reaction pathways or rates of reactions involved in breakdown of the phosphoenzymes.