ID   1.14.13.246
DE   4-beta-methylsterol monooxygenase.
CA   A 3-beta-hydroxy-4,4-dimethylsteroid + 3 NADH + 3 O(2) = a 3-beta-
CA   hydroxy-4-beta-carboxy-4-alpha-methylsteroid + 3 NAD(+) + 4 H(2)O.
CC   -!- Contains a Rieske [2Fe-2S] iron-sulfur cluster.
CC   -!- This bacterial enzyme (SdmA) participates in the biosynthesis of
CC       bacterial sterols.
CC   -!- Together with SdmB it forms an enzyme system that removes one methyl
CC       group from the C-4 position of 4,4-dimethylated steroid molecules.
CC   -!- SdmA catalyzes three successive oxidations of the C-4-beta methyl
CC       group, turning it into a carboxylate group; the second enzyme, SdmB,
CC       is a bifunctional enzyme that catalyzes two different activities.
CC   -!- As EC 1.1.1.417 it catalyzes an oxidative decarboxylation that
CC       results in reduction of the 3-beta-hydroxy group at the C-3 carbon to
CC       an oxo group.
CC   -!- As EC 1.1.1.270 it reduces the 3-oxo group back to a 3-beta-hydroxyl.
CC   -!- Unlike the animal/fungal enzyme EC 1.14.18.9 and the plant enzymes
CC       EC 1.14.18.10 and EC 1.14.18.11, this enzyme acts preferentially on
CC       the 4-beta-methyl group.
CC   -!- Since no epimerization of the remaining C-4-alpha methyl group
CC       occurs, the enzyme can only remove one methyl group, leaving a
CC       4-alpha-monomethylated product.
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