Accepted name: stachydrine N-demethylase
Reaction: L-proline betaine + NAD(P)H + H+ + O2 = N-methyl-L-proline + formaldehyde + NAD(P)+ + H2O
Other name(s): L-proline betaine N-demethylase; stc2 (gene name)
Systematic name: L-proline betaine,NAD(P)H:oxygen oxidoreductase (formaldehyde-forming)
Comments: The enzyme, characterized from the bacterium Sinorhizobium meliloti 1021, consists of three different types of subunits. The catalytic unit contains a Rieske [2Fe-2S] iron-sulfur cluster, and catalyses the monooxygenation of a methyl group. The resulting N-methoxyl group is unstable and decomposes spontaneously to form formaldehyde. The other subunits are involved in the transfer of electrons from NAD(P)H to the catalytic subunit.
1.  Daughtry, K.D., Xiao, Y., Stoner-Ma, D., Cho, E., Orville, A.M., Liu, P. and Allen, K.N. Quaternary ammonium oxidative demethylation: X-ray crystallographic, resonance Raman, and UV-visible spectroscopic analysis of a Rieske-type demethylase. J. Am. Chem. Soc. 134 (2012) 2823–2834. [PMID: 22224443]
2.  Kumar, R., Zhao, S., Vetting, M.W., Wood, B.M., Sakai, A., Cho, K., Solbiati, J., Almo, S.C., Sweedler, J.V., Jacobson, M.P., Gerlt, J.A. and Cronan, J.E. Prediction and biochemical demonstration of a catabolic pathway for the osmoprotectant proline betaine. MBio 5 (2014) e00933. [PMID: 24520058]
[EC created 2017]