Mason J I, Arunachalam T, Caspi E
Biochim Biophys Acta. 1983 Jul 12;752(2):265-76. doi: 10.1016/0005-2760(83)90122-4.
The cholesterol side-chain cleavage enzyme system of rat adrenal mitochondria and rat adrenocortical carcinoma cells was found to metabolize three halogenated side-chain cholesterol analogues to pregnenolone. The analogues were 26-bromocholesterol, 26-nor-25(RS)-bromocholesterol and 26-iodocholesterol. The addition of Ca2+ to rat adrenal mitochondria did not produce an increase in the rate of metabolism of the halogenated sterol to pregnenolone. The brominated sterols suppressed the de novo sterol biosynthesis of rat adrenocortical carcinoma cells. The experimental findings are supportive of the notion that a halogen atom at such a position in a sterol is analogous to a hydroxyl group but unlike a proton. ACTH, therefore, may not be a requirement for the uptake and utilization of such sterols. The halogenated sterols may have a use as probes in the study of sterol transfer into and within cells.
已发现大鼠肾上腺线粒体和大鼠肾上腺皮质癌细胞的胆固醇侧链裂解酶系统可将三种卤代侧链胆固醇类似物代谢为孕烯醇酮。这些类似物分别是26-溴胆固醇、26-降-25（RS）-溴胆固醇和26-碘胆固醇。向大鼠肾上腺线粒体中添加Ca2+并不会使卤代固醇代谢为孕烯醇酮的速率增加。溴化固醇抑制了大鼠肾上腺皮质癌细胞的从头固醇生物合成。实验结果支持这样一种观点，即固醇中该位置的卤原子类似于羟基，但不同于质子。因此，促肾上腺皮质激素可能不是摄取和利用此类固醇的必要条件。卤代固醇可能可用作研究固醇转运入细胞和在细胞内转运的探针。
