EC 1.17.99.10     
Accepted name: steroid C-25 hydroxylase
Reaction: cholest-4-en-3-one + acceptor + H2O = 25-hydroxycholest-4-en-3-one + reduced acceptor
Other name(s): s25dA1 (gene name); s25dA1B3 (gene name); s25dA1C3 (gene name); cholesterol C-25 dehydrogenase; steroid C-25 dehydrogenase
Systematic name: cholest-4-en-3-one:acceptor oxidoreductase (25-hydroxylating)
Comments: The enzyme, characterized from the bacterium Sterolibacterium denitrificans, participates in the anaerobic degradation of cholesterol. The enzyme can accept several substrates including vitamin D3. The enzyme contains a bis(guanylyl molybdopterin) cofactor, five [Fe-S] clusters, and one heme b. cf. EC 1.14.99.38, cholesterol 25-monooxygenase, an oxygen-requiring eukaryotic enzyme that catalyses a similar transformation.
References:
1.  Dermer, J. and Fuchs, G. Molybdoenzyme that catalyzes the anaerobic hydroxylation of a tertiary carbon atom in the side chain of cholesterol. J. Biol. Chem. 287 (2012) 36905–36916. [PMID: 22942275]
2.  Rugor, A., Tataruch, M., Staron, J., Dudzik, A., Niedzialkowska, E., Nowak, P., Hogendorf, A., Michalik-Zym, A., Napruszewska, D.B., Jarzebski, A., Szymanska, K., Bialas, W. and Szaleniec, M. Regioselective hydroxylation of cholecalciferol, cholesterol and other sterol derivatives by steroid C25 dehydrogenase. Appl. Microbiol. Biotechnol. 101 (2017) 1163–1174. [PMID: 27726023]
3.  Rugor, A., Wojcik-Augustyn, A., Niedzialkowska, E., Mordalski, S., Staron, J., Bojarski, A. and Szaleniec, M. Reaction mechanism of sterol hydroxylation by steroid C25 dehydrogenase - Homology model, reactivity and isoenzymatic diversity. J. Inorg. Biochem. 173 (2017) 28–43. [PMID: 28482186]
4.  Jacoby, C., Eipper, J., Warnke, M., Tiedt, O., Mergelsberg, M., Stark, H.J., Daus, B., Martin-Moldes, Z., Zamarro, M.T., Diaz, E. and Boll, M. Four molybdenum-dependent steroid C-25 hydroxylases: heterologous overproduction, role in steroid degradation, and application for 25-hydroxyvitamin D3 synthesis. mBio 9:e00694-18 (2018). [PMID: 29921665]
[EC 1.17.99.10 created 2020]