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.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
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]