ATP formation from ADP and a phosphorylated intermediate of Ca2+-dependent ATPase in fragmented sarcoplasmic reticulum.
ATP formation from ADP and a phosphorylated intermediate of Ca2+-dependent ATPase in fragmented sarcoplasmic reticulum.
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ATP 由 ADP 和碎片肌浆网中 Ca2 依赖性 ATP 酶的磷酸化中间体形成。
DOI：
10.1093/oxfordjournals.jbchem.a129392
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
Y. Tonomura
中科院分区：
文献类型：
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作者：
T. Kanazawa;S. Yamada;Y. Tonomura
Yamamoto和Tonomura(1，2)先前证明了从ƒα-32P-ATP(AT32P)到钙依赖的ATPase[ATP磷酸水解酶，EC3.6]的‘-P-掺入。1.在Mg~(2+)和Ca~(2+)同时存在下，从兔骨骼肌中分离出31个片段的SR，为磷酸化酶(EP)是ATPase反应的催化中间体提供了动力学证据。然而，Hassel Bach和Makinose观察到的SR中，EP的能量水平是否足够高来调节依赖钙的ATP-ADP交换反应还不确定(3)。因此，目前的实验一直在进行，以了解ATP是否由EP和ADP形成。SR从兔骨骼肌中分离出来，如前所述(4)。在初步实验中，将SR(0.244 mg/ml蛋白质)在0.821毫升的反应介质中与12.2ƒ的非放射性三磷酸腺苷进行磷酸化，该反应介质含有1.22mM的氯化镁、24.4、122mMCaCl2、122mMKCl1和122mM的三马来酸，在pH 7.0的15℃下反应10秒，然后用我们所描述的混合装置加入0.088毫升的51.5ƒ的AT32P
Yamamoto and Tonomura(1, 2) previously demonstrated'-P-incorporation from ƒÁ-32P-ATP (AT32P) into Ca2+-dependent ATPase[ATP phosphohydrolase, EC 3.6. 1. 31 of fragmented SR from rabbit skeletal muscle in the presence of both Mg2+ and Ca2+, and provided kinetic evidence that the phosphorylated enzyme(EP) is a catalytic intermediate in the ATPase reaction. However, it was uncertain whether the energy level of EP was sufficiently high to mediate the Ca2+-dependent ATP-ADP exchange reaction in the SR observed by Hassel bach and Makinose(3). Thus the present experiments have been undertaken to see whether ATP is formed from EP and ADP. SR was isolated from rabbit skeletal muscle as described previously(4). In a preliminary experiment, SR (0.244 mg/ml protein) was phos phorylated with 12.2 ƒÊM nonradioactive ATP in 0.821 ml of reaction medium containing 1.22 mm MgCl2, 24.4, ƒÊM CaCl2, 122 mm KCl and 122 mm Tris-maleate, pH 7.0, for 10 sec at 15 C, and then 0.088 ml of 51.5 ƒÊM AT32P was added using the mixing apparatus we described pre