肌浆网片段储存对Ca2+、Mg2+-ATP酶的影响。

The effects of storage of sarcoplasmic reticulum fragments on the Ca2+, Mg2+-ATPase.

作者信息

Nakamura J, Konishi K

出版信息

J Biochem. 1978 Jun;83(6):1731-5. doi: 10.1093/oxfordjournals.jbchem.a132087.

DOI:10.1093/oxfordjournals.jbchem.a132087

Abstract

The effects of K+ and Na+ on the Ca2+,Mg2+-ATPase of sarcoplasmic reticulum fragments (SRF) were investigated at 1 mM ATP. There was an alteration of the sensitivity of the ATPase to the monovalent cations during storage of the SRF preparation. The Ca2+, Mg2+-ATPase of freshly prepared SRF was slightly activated by 5-10 mM K+ and Na+. Mg2+-ATPase was inhibited by both the monovalent cations to the same extent, and this response to the ions was independent of the freshness of the preparations. After storage of SRF, however, the Ca2+,Mg2+-ATPase was markedly activated by higher concentrations of K+ and Na+ (0.2-0.3 M). K+ and Na+ reduced the Ca uptake at the steady state in freshly prepared SRF, but did not affect pre-steady state uptake. In the presence of oxalate, the rate of Ca accumulation both in fresh and stored preparations was activated by 0.1-0.2 M K+ and Na+. The Ca2+, mg2+-ATPase with oxalate, so-called "extra ATPase," showed the same response to the ions as did the activity without oxalate during storage.

摘要

在1 mM ATP条件下，研究了钾离子（K⁺）和钠离子（Na⁺）对肌浆网片段（SRF）的钙离子（Ca²⁺）、镁离子（Mg²⁺）-ATP酶的影响。在SRF制剂储存期间，ATP酶对单价阳离子的敏感性发生了改变。新鲜制备的SRF的Ca²⁺、Mg²⁺-ATP酶被5 - 10 mM的K⁺和Na⁺轻微激活。Mg²⁺-ATP酶受到这两种单价阳离子同等程度的抑制，并且这种对离子的反应与制剂的新鲜度无关。然而，SRF储存后，Ca²⁺、Mg²⁺-ATP酶被更高浓度的K⁺和Na⁺（0.2 - 0.3 M）显著激活。K⁺和Na⁺降低了新鲜制备的SRF在稳态时的钙摄取，但不影响稳态前的摄取。在草酸盐存在的情况下，新鲜制剂和储存制剂中的钙积累速率均被0.1 - 0.2 M的K⁺和Na⁺激活。含草酸盐的Ca²⁺、Mg²⁺-ATP酶，即所谓的“额外ATP酶”，在储存期间对离子的反应与不含草酸盐时的活性相同。