Differences in the metabolism of vitamin D2 and vitamin D3 by subcellular fractions from rat liver

Abstract The 25-hydroxylation of vitamin D 2 and vitamin D 3 was studied in the mitochondrial fraction from rat liver and in a reconstituted system containing cytochrome P -450 from rat liver microsomes. The mitochondrial fraction catalyzed the 25-hydroxylation of vitamin D 3 at least two times more effectively than the 25-hydroxylation of vitamin D 2 . Microsomal cytochrome P -450 catalyzed an efficient 25-hydroxylation of vitamin D 3 , but no 25-hydroxylation of vitamin D 2 could be detected. The present results show a difference in the 25-hydroxylation of vitamin D 2 and vitamin D 3 in rat liver in vitro.