In enzymology, a 7alpha-hydroxycholest-4-en-3-one 12alpha-hydroxylase () is an enzyme that catalyzes the chemical reaction:7alpha-hydroxycholest-4-en-3-one + NADPH + H+ + O2 formula_1 7alpha,12alpha-dihydroxycholest-4-en-3-one + NADP+ + H2OThe 4 substrates of this enzyme are 7alpha-hydroxycholest-4-en-3-one (7 alpha-hydroxy-4-cholesten-3-one, NADPH, H+, and O2, whereas its 3 products are 7alpha,12alpha-dihydroxycholest-4-en-3-one, NADP+, and H2O.
La 5beta-colestano-3alfa,7alfa-diolo 12alfa-idrossilasi è un enzima appartenente alla classe delle ossidoreduttasi, che catalizza la seguente reazione::5β-colestano-3α,7α-diolo + NADPH + H+ + O2 5β-colestano-3α,7α,12α-triolo + NADP+ + H2OL'enzima è una proteina eme-tiolata ("P"-450).