Fig. 1: Mo-CODHMs oxidizes CO with high catalytic efficiency to below atmospheric concentrations.
From: Quinone extraction drives atmospheric carbon monoxide oxidation in bacteria
a, Gas chromatography analysis of the CO concentration of the headspace of sealed vials containing Mo-CODHMs or no enzyme, with 200 μM menadione as the electron acceptor. b, Gas chromatography analysis of the CO concentration of the headspace of sealed vials containing Mo-CODHMs or no enzyme, with 50 μM methylene blue as the electron acceptor. Mo-CODHMs can oxidize CO below atmospheric concentrations (black dashed line). In a and b, data are the mean ± s.d. c, Steady-state Michaelis–Menten kinetics of Mo-CODHMs consumption of CO in the headspace of sealed vials with 50 μM methylene blue as the electron acceptor. Repeat measurements shown in a–c were conducted on distinct samples. d, Steady-state Michaelis–Menten kinetics of Mo-CODHAc consumption of CO in the headspace of sealed vials, with 50 μM methylene blue as the electron acceptor. e, DC voltammogram of surface-confined Mo-CODHMs on a PIGE electrode obtained at pH 8.0, under N2 (scan rate = 100 mV s−1, T = 21 °C). Mo labels the peak likely corresponding to the redox transitions of the Mo cofactor, while * and *′ label peaks that correspond to unassigned redox processes possibly attributable to the enzyme FeS clusters or FAD. f, Comparison of the DC voltammograms obtained at pH 8.0, under N2 (black line), CO (red) and CO2 (blue) saturation (scan rate = 50 mV s−1, T = 21 °C). A positive shift of approximately +110 mV for the MoVI/IV process was observed because of the decrease in pH when the solution was saturated with CO2. Voltammetry was conducted five times on three separately prepared samples, with a representative sample shown. conc., concentration; MoVI/IV, change in the charge of the Mo ion from 6+ to 4+.
