The NR, NR, -tétraméthyl-1,4-phénylènediamine are not component reagent of the research of the Cytochrome-oxydase in bacteriology. Indeed, in the presence of dioxygene, the cytochrome-oxydase is able to catalyze the oxidation of the reduced form of N-methylated derivatives of the Paraphénylènediamine in semi-quinone (pink purplished).