Fig. 3: NicA2 variants are rapidly oxidized by O2.
From: Directed evolution unlocks oxygen reactivity for a nicotine-degrading flavoenzyme
a, Schematic of the reaction of NicA2 with nicotine; Flox, oxidized flavin; Flred, reduced flavin. b, Example traces for the stopped-flow reaction of reduced NicA2 v320 with O2 at a concentration of 450 μM. Raw traces for reactions at all concentrations of O2 can be seen in Supplementary Fig. 1a–h. The second phase of the reaction of NicA2 v320 in the presence of myosmine likely represents a subpopulation of the enzyme that is reacting with O2 in the ligand-free state (Supplementary Fig. 1i). Also shown are the chemical structures for NMM and myosmine. c, Example traces for the reaction of reduced wild-type NicA2 with O2 at a concentration of 450 μM. d, kobs values for the first phase of oxidation are plotted against O2 concentration ([O2]) and fit to a line. The slopes of these lines define the bimolecular rate constants for oxidation by O2, which are presented in numeric form in Table 1.
