The formation of the highly reactive oxygen species hydrogen peroxide and superoxide radical in the cell may lead to deleterious effects. Two cellular enzymes that quench reactive oxygen species are catalase and superoxide dismutase. Recently, the oxyacid methanesulfinate (CH3S(O)O–) was reported as the biochemical product of a reduced flavin (FMNH–)-dependent monooxygenase, providing for the first time an in vivo metabolic role for methanesulfinate. In the reaction, the enzyme MsuE functions as a reduced nicotinamide adenine dinucleotide (NADH)-dependent flavin reductase; FMNH– is used by the monooxygenase as a co-substrate to convert dimethylsulfone to methanesulfinate. Interestingly, in the presence of MsuE and the substrates NADH and FMN, but in the absence of the monooxygenase, methanesulfinate is oxidized to the oxyacid methanesulfonate (CH3S(O)2O–). Presumably, free FMNH– formed via MsuE, NADH, and FMN reacts with molecular oxygen and produces (hydro)peroxyflavin, hydrogen peroxide, and superoxide radical. One or more of the aforementioned chemical species may facilitate the S-O bond forming reaction observed in the conversion of sulfinate to sulfonate. The presence of catalase and superoxide dismutase in the aerobic assay provides insight into methanesulfinate oxidation. Aerobic assays were conducted in buffered aqueous solutions with methanesulfinate, NADH, FMN, MsuE, and varied amounts of catalase and/or superoxide dismutase. The sulfur-containing chemical species present as a function of time were identified by 1H NMR spectroscopy, thus providing insight into the oxidants capable of transforming the metabolite methanesulfinate.

Oxidation of methanesulfinate to methanesulfonate in the presence of catalase and superoxide dismutase

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.