Five subcellular fractions were obtained by successive centrifugation from the liver of rats within 6 hours of life and characterized by comparing marker compound or marker enzyms. After incubating 3¥â-hydroxy-5¥á-pregnan-20-one with the each fraction, the steroids were analyzed by TLC, GLC and GC-MS.
A 6¥á-hydroxylase which hydroxylizes the tetra-hydrogenated compound of progesterone, 3¥â-hydroxy-5¥á-pregnan-20-one, was localized in the crude plasma membrane fraction, but not in the microsome fraction.
The maximum 6¥á-hydroxylation was observed at pH 7.0. While this 6¥á-steroid hydroxylase was not able to hydroxlyze the progesterone, the 3¥á-isomer was hydroxylized at the 6¥á-position.
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