大鼠肥大细胞质膜中钙离子激活的三磷酸腺苷酶的特性研究
Characterization of calcium-ion-activated adenosine triphosphatase in the plasma membrane of rat mast cells.
作者信息
Cooper P H, Stanworth D R
出版信息
Biochem J. 1976 Jun 15;156(3):691-700. doi: 10.1042/bj1560691.
The properties of a Ca2+ activated adenosine triphosphatase shown to be present in homogenates of purified rat peritoneal mast cells were investigated. The enzyme was activated by Ca2+, Mg2+, and to a lesser extent by Mn2+ and Co2+. Ca2+ alone was necessary for full activity and the further addition of Mg2+ did not have any effect. The chelating agents EGTA (ethanedioxybis(ethylamine)tetra-acetate) and EDTA completely inhibited the reaction. The pH optimum was 7.8. Reduced glutathione, cysteine, dithiothreitol, N-ethylmaleimide, urea, ADP, NaF, increasing ionic strength and Triton X-100 all inhibited the reaction. On subcellular fractionation of mast-cell homogenates by density-gradient centrifugation, the distribution of Ca2+ activated adenosine triphosphatase resembled that of 5'-nucleotidase, but differed from that of the other markers used, suggesting localization in the plasma membrane. Further experiments indicated that the enzyme is present on the external surface of the plasma membrane.
对纯化的大鼠腹膜肥大细胞匀浆中存在的一种钙离子激活的三磷酸腺苷酶的特性进行了研究。该酶被钙离子、镁离子激活，锰离子和钴离子在较小程度上也能激活。仅钙离子是充分发挥活性所必需的，进一步添加镁离子没有任何作用。螯合剂乙二醇双（乙胺）四乙酸（EGTA）和乙二胺四乙酸（EDTA）完全抑制该反应。最适pH为7.8。还原型谷胱甘肽、半胱氨酸、二硫苏糖醇、N-乙基马来酰亚胺、尿素、二磷酸腺苷（ADP）、氟化钠、增加离子强度以及曲拉通X-100均抑制该反应。通过密度梯度离心对肥大细胞匀浆进行亚细胞分级分离时，钙离子激活的三磷酸腺苷酶的分布类似于5'-核苷酸酶，但与所使用的其他标志物的分布不同，提示其定位于质膜。进一步的实验表明该酶存在于质膜的外表面。
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