Anaerobically grown Escherichia coli cells were shown to acidify the reaction medium in response to oxygen or dimethyl sulfoxide (DMSO) pulses, with the H+/e- stoichiometry being close to 2.5 and 1.5, respectively. In the presence of the NADH dehydrogenase I (NDH-I) inhibitor 8-methyl-N- vanillyl-6-nonenamide (capsaicin) or in mutants lacking NDH-I, this ratio decreased to 1 for O2 and to 0 for DMSO. These data suggest that (i) the H+/e- stoichiometry for E. coli NDH-I is at least 1.5 and (ii) the DMSO reductase does not generate a proton motive force.
ASJC Scopus subject areas
- Molecular Biology