Reactome | CYP11A1 cleaves 20a,22b-DHCHOL

CYP11A1 cleaves 20a,22b-DHCHOL

Stable Identifier

R-HSA-193101

Type

Reaction [transition]

Species

Homo sapiens

Compartment

mitochondrial matrix, mitochondrial inner membrane

Synonyms

(20R,22R)-20,22-dihydroxycholesterol + 2 H(+) + O2 + 2 reduced (adrenodoxin) => 4-methylpentanal + 2 H2O + 2 oxidized (adrenodoxin) + pregnenolone, 20alpha,22beta-hydroxycholesterol is cleaved by CYP11A1 to yield pregnenolone and isocaproaldehyde, 20alpha,22beta-hydroxycholesterol + NADPH + H+ + O2 => pregnenolone + isocaproaldehyde + NADP+ + H2O

ReviewStatus

5/5

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Metabolism (Homo sapiens)

- Biological oxidations (Homo sapiens)
  - Phase I - Functionalization of compounds (Homo sapiens)
    - Cytochrome P450 - arranged by substrate type (Homo sapiens)
      - Endogenous sterols (Homo sapiens)
        
        CYP11A1 cleaves 20a,22b-DHCHOL (Homo sapiens)
- Metabolism of lipids (Homo sapiens)
  - Metabolism of steroids (Homo sapiens)
    - Metabolism of steroid hormones (Homo sapiens)
      - Pregnenolone biosynthesis (Homo sapiens)
        
        CYP11A1 cleaves 20a,22b-DHCHOL (Homo sapiens)

General

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20alpha,22beta-hydroxycholesterol (20a,22b-DHCHOL), NADPH + H+, and O2 react to form pregnenolone (PREG), isocaproaldehyde (ISCAL), NADP+ and H2O. This cleavage reaction is catalysed by CYP11A (P450scc) associated with the inner mitochondrial membrane (Strushkevich et al. 2011). PREG is substantially more hydrophilic than cholesterol (CHOL) and hydroxycholesterol (HCHOL) and is released into the mitochondrial matrix.

Literature References

PubMed ID	Title	Journal	Year
3024157	Human cholesterol side-chain cleavage enzyme, P450scc: cDNA cloning, assignment of the gene to chromosome 15, and expression in the placenta Miller, WL, Chung, BC, Voutilainen, R, Mohandas, TK, Matteson, KJ	Proc Natl Acad Sci U S A	1986
21636783	Structural basis for pregnenolone biosynthesis by the mitochondrial monooxygenase system Park, HW, Grabovec, I, Usanov, S, MacKenzie, F, Cherkesova, T, Strushkevich, N	Proc. Natl. Acad. Sci. U.S.A.	2011
9578606	Expression of catalytically active human cytochrome p450scc in Escherichia coli and mutagenesis of isoleucine-462 Downs, T, Tuckey, RC, Woods, ST, Triantopoulos, T, Sadleir, J, Headlam, MJ	Arch Biochem Biophys	1998