Functional characterization of 3-ketosteroid 9 alpha-hydroxylases in Rhodococcus ruber strain chol-4

摘要

The 3-Ketosteroid-9 alpha-Hydroxylase, also known as KshAB [androsta-1,4-diene-3,17-dione, NADH:oxygen oxidoreductase (9 alpha-hydroxylating); EC 1.14.13.142)], is a key enzyme in the general scheme of the bacterial steroid catabolism in combination with a 3-ketosteroid-Delta(1)-dehydrogenase activity (KstD), being both responsible of the steroid nucleus (rings A/B) breakage. KshAB initiates the opening of the steroid ring by the 9 alpha-hydroxylation of the C9 carbon of 4-ene-3-oxosteroids (e.g. AD) or 1,4-diene-3-oxosteroids (e.g. ADD), transforming them into 9 alpha-hydroxy-4-androsten-3,17-dione (9OHAD) or 9 alpha-hydroxy-1,4-androstadiene-3,17-dione (9OHADD), respectively.