:Cholest-4-en-3-one 26-monooxygenase

{{Short description|Class of enzymes}}

{{Infobox enzyme

| Name = Cholest-4-en-3-one 26-monooxygenase

| EC_number = 1.14.13.141

| CAS_number =

| GO_code =

| image =

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Cholest-4-en-3-one 26-monooxygenase ({{EC number|1.14.13.141}}, CYP125, CYP125A1, cholest-4-en-3-one 27-monooxygenase) is an enzyme with systematic name cholest-4-en-3-one,NADH:oxygen oxidoreductase (26-hydroxylating).{{cite journal | vauthors = Rosłoniec KZ, Wilbrink MH, Capyk JK, Mohn WW, Ostendorf M, van der Geize R, Dijkhuizen L, Eltis LD | title = Cytochrome P450 125 (CYP125) catalyses C26-hydroxylation to initiate sterol side-chain degradation in Rhodococcus jostii RHA1 | journal = Molecular Microbiology | volume = 74 | issue = 5 | pages = 1031–43 | date = December 2009 | pmid = 19843222 | pmc = 5218833 | doi = 10.1111/j.1365-2958.2009.06915.x }}{{cite journal | vauthors = McLean KJ, Lafite P, Levy C, Cheesman MR, Mast N, Pikuleva IA, Leys D, Munro AW | title = The Structure of Mycobacterium tuberculosis CYP125: molecular basis for cholesterol binding in a P450 needed for host infection | journal = The Journal of Biological Chemistry | volume = 284 | issue = 51 | pages = 35524–33 | date = December 2009 | pmid = 19846552 | pmc = 2790982 | doi = 10.1074/jbc.M109.032706 | doi-access = free }}{{cite journal | vauthors = Capyk JK, Kalscheuer R, Stewart GR, Liu J, Kwon H, Zhao R, Okamoto S, Jacobs WR, Eltis LD, Mohn WW | title = Mycobacterial cytochrome p450 125 (cyp125) catalyzes the terminal hydroxylation of c27 steroids | journal = The Journal of Biological Chemistry | volume = 284 | issue = 51 | pages = 35534–42 | date = December 2009 | pmid = 19846551 | pmc = 2790983 | doi = 10.1074/jbc.M109.072132 | doi-access = free }}{{cite journal | vauthors = Ouellet H, Guan S, Johnston JB, Chow ED, Kells PM, Burlingame AL, Cox JS, Podust LM, de Montellano PR | title = Mycobacterium tuberculosis CYP125A1, a steroid C27 monooxygenase that detoxifies intracellularly generated cholest-4-en-3-one | journal = Molecular Microbiology | volume = 77 | issue = 3 | pages = 730–42 | date = August 2010 | pmid = 20545858 | pmc = 2909382 | doi = 10.1111/j.1365-2958.2010.07243.x }} This enzyme catalyses the following chemical reaction

: cholest-4-en-3-one + NADH + H⁺ + O₂ $\backslash rightleftharpoons$ 26-hydroxycholest-4-en-3-one + NAD⁺ + H₂O

Cholest-4-en-3-one 26-monooxygenase is a heme thiolate (P450) enzyme.