(24S)-7alpha-dihydroxycholesterol + NAD(+) => (24S)-7alpha,24-dihydroxycholest-4-en-3-one + NADH + H(+)
(24s)-7alpha-dihydroxycholesterol + nad(+) => (24s)-7alpha,24-dihydroxycholest-4-en-3-one + nadh + h(+)