Oxygen consumption in isolated E. coli membranes from cells expressing the Arabidopsis IMMUTANS gene product (PTOX) and control cells. a, Oxygen uptake was measured using an O2 electrode after addition of NADH as an electron donor, KCN, and n-propyl-gallate (nPG). Dithionite (Na2S2O4) was added at the end of the experiment to verify that the reactions did not proceed to complete oxygen depletion. Numbers refer to oxygen consumption in nmol O2 min−1 mg−1 protein in the linear zone of the traces (when full effect of the added compound was obtained). b, Relative respiration rate after sequential addition of NADH (set as 100), KCN, and nPG. Means of 12 experiments and se are shown. c, Same as a except that nPG was added prior to KCN. Traces are of the same scale in a given panel.