Effect of calcium(ion) uptake by rat adrenal mitochondria on pregnenolone formation and spectral properties of cytochrome P-450.
Effect of calcium(ion) uptake by rat adrenal mitochondria on pregnenolone formation and spectral properties of cytochrome P-450.
复制标题
大鼠肾上腺线粒体摄取钙（离子）对孕烯醇酮形成和细胞色素 P-450 光谱特性的影响。
DOI：
10.1016/0304-4165(75)90338-4
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发表时间：
1975
期刊：
影响因子：
--
通讯作者：
D. Williams
中科院分区：
文献类型：
--
作者：
E. Simpson;D. Williams
在大鼠去囊肾上腺和有囊肾上腺的线粒体中研究了钙对内源性前体化合物去甲烯醇酮形成的影响。在琥珀酸存在的情况下，加入浓度范围为20-150 μM的氯化钙导致去去膜肾上腺线粒体中加入的脱氧Costicosterone形成的抑制也受到抑制。在这些条件下，钙抑制肾上腺素，细胞色素P-450还原酶系统的一个组成部分的减少，大概是因为线粒体的钙的摄取与能量相关的转氢酶的高能量中间体的竞争。因此，在存在琥珀酸盐+异柠檬酸盐+NADP+的情况下进行孵育。在这些条件下，浓度范围为120-875 μM的氯化钙引起了2-4倍的双烯醇酮生成刺激，但对加入脱氧皮质酮的皮质酮生成没有影响。在琥珀酸的存在下，钙诱导的光谱变化类似于I型差异光谱的cytochromeP-450。因此，钙的摄取似乎是线粒体细胞色素P-450与内源性底物相互作用的结果.
The effect of calcium on pregnenolone formation from endogenous precursors has been studied in mitochondria from rat decapsulated and capsular adrenalgglands. In the presence of succinate, addition of calcium chloride in the concentration range 20–150 μM caused an inhibition of pregnenolone formation of added deoxycosticosterone in decapsulated adrenal mitochondria was also inhibited. Under these conditions, calcium inhibited the reduction of adrenodoxin, a component of the cytochromeP-450 reductase system, presumably because uptake of calcium by the mitochondria competes with energy-linked transhydrogenase for high-energy intermediates. For this reason, incubations were carried out in the presence of succinate plus isocitrate plus NADP+. Under these conditions, calcium chloride in the concentration range 120–875 μM caused a 2–4-fold stimulation of pregnenolone formation, but had no effect on corticosterone formation from added deoxycorticosterone.The effect of calcium on the optical spectra of cytochromeP-450 has also been examined in mitochondria from decapsulated and capsular rat adrenals. In the presence of succinate, calcium induced a spectral change resembling a type I difference spectrum of cytochromeP-450. Thus it appears that uptake of calcium the interaction of mitochondrial cytochromeP-450 with endogenous substrate.