Conversion of 7-Dehydrocholesterol to 7-Ketocholesterol Is Catalyzed by Human Cytochrome P450 7A1 and Occurs by Direct Oxidation without an Epoxide Intermediate

On the formation of 7-ketocholesterol from 7-dehydrocholesterol in patients with CTX and SLO

“…To summarize, the present results suggest that 7-dehydrocholesterol is likely to be a precursor to 7-ketocholesterol, not only under the in vitro conditions previously described ( 8 ) but also under in vivo conditions with high levels of 7-dehydrocholesterol. The high levels of 7-dehydrocholesterol must be combined with normal or high activity of the cholesterol 7 ␣ -hydroxylase.…”

“…described a new pathway from 7-dehydrocholesterol into 7-ketocholesterol with cholesterol-7,8-epoxide (cholest-5-en-7,8-epoxide) as a side product. In parallel with this there is a conversion of lathosterol into a mixture of 7-ketocholestanol and cholestanol-7,8-epoxide ( 8 ). Both conversions were found to be catalyzed by the human cholesterol 7 ␣ -hydroxylase (CYP7A1).…”

Evaluation of plasma cholestane-3β,5α,6β-triol and 7-ketocholesterol in inherited disorders related to cholesterol metabolism

“…Therefore, the high oxysterol levels observed In SLOS patients, the defect of 7-dehydrocholesterol reductase causes a massive accumulation of 7-dehydrocholesterol (7-DHC) ( 22 ). The fi nding of increased 7-KC alone in SLOS patients can therefore be easily explained by conversion of excessive 7-DHC into 7-KC ( 23 ). FH is a rare autosomal dominant genetic disorder that leads to a massive increase of blood cholesterol in most cases due to mutations in the LDL receptor gene ( 24 ).…”

Unusual Cytochrome P450 Enzymes and Reactions

“…Notable examples are the conversion of vinyl halides to ␣-haloacetaldehydes (18,28). A recent similar example involves the "direct" conversion of 7,8-dehydrocholesterol to 7-ketocholesterol by the human P450 CYP7A1 (29). Strained cycloalkyl rings undergo rearrangements (2,30).…”