ATP-DRIVEN ACTIVE TRANSPORT OF CALCIUM IN MEMBRANES OF SARCOPLASMIC RETICULUM
ATP-DRIVEN ACTIVE TRANSPORT OF CALCIUM IN MEMBRANES OF SARCOPLASMIC RETICULUM
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DOI：
10.1098/rspb.1964.0064
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发表时间：
1964-01-01
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影响因子：
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通讯作者：
HASSELBACH, W
中科院分区：
文献类型：
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作者：
HASSELBACH, W
肌浆网分离的囊泡从含草酸盐的溶液中吸收钙的过程中，钙在囊泡内以草酸钙的形式积累，直到囊泡内的钙和草酸的活性浓度的乘积比外面高约5000倍。所涉及的离子产物的增加是由钙泵而不是草酸盐泵引起的。钙的吸收与钙诱导的 ATP（额外 ATP 酶）分裂以及钙诱导的 ATP 和 ADP 之间的 P 交换密切相关。两种反应都取决于外部游离钙离子的浓度，并且当游离钙离子的水平降低至约10-8至10-9M的值时停止。只要游离钙浓度超过 10-7M，每摩尔 ATP 分裂，亚分级的囊泡就会吸收 2 摩尔钙。当游离钙浓度降至 10-7M 以下时，储存的钙与 ATP 分裂的比率下降至 1。 20°C 时，囊泡最活跃的部分积累了 12 微摩尔钙 (mg N)-1 min-1。
During the uptake of calcium by the isolated vesicles of the sarcoplasmic reticulum from oxalate-containing solutions, calcium is accumulated inside the vesicles as calcium oxalate, until the product of the active concentrations of calcium and oxalate inside is about 5000 times higher than outside. The increase of the product of the ions involved is brought about by a calcium pump and not by an oxalate pump. The uptake of calcium is strictly correlated with the calcium-induced splitting of ATP (extra ATPase) as well as with the calcium-induced P-exchange between ATP and ADP. Both reactions depend on the concentration of the free calcium ions outside and cease when the level of the free calcium ions has been reduced to values about 10-8 to 10-9M. Vesicles subfractionated take up 2 moles of calcium for every mole of ATP split as long as the concentration of free calcium exceeds 10-7M. The ratio of calcium stored to ATP split declines to a value of 1 when the concentration of free calcium is reduced below 10-7M. 12 [mu]moles calcium (mg N)-1 min-1 are accumulated by the most active fraction of the vesicles at 20 [degree]C.