Quinone reductase that provides resistance to thiol-specific stress caused by electrophilic quinones (Probable). Contributes to resistance to 2-methylhydroquinone (2-MHQ) and catechol (PubMed:17725564, PubMed:18208493). Exhibits NADH-dependent 2,6-dichloroindophenol (DCIP) oxidoreductase activity (PubMed:17284825). Also exhibits azoreductase activity. Catalyzes the reductive cleavage of the azo bond in aromatic azo compounds to the corresponding amines (PubMed:17284825). Can reduce methyl red (PubMed:17284825). 2 a quinone + H(+) + NADH = 2 a 1,4-benzosemiquinone + NAD(+) anthranilate + N,N-dimethyl-1,4-phenylenediamine + 2 NAD(+) = 2-(4-dimethylaminophenyl)diazenylbenzoate + 2 H(+) + 2 NADH Binds 1 FMN per subunit. Strongly inhibited by Pb(2+) and weakly inhibited by Cu(2+), Hg(2+) and Fe(2+). Stable in presence of Ag(+). Optimum pH is 7.5. Activity increases linearly up to 40 degrees Celsius. Stable up to 55 degrees Celsius after incubation for 30 min at pH 7.5. During incubation at 25 degrees Celsius for 16h, the enzyme is stable between pH 5.5 and 9.0, where 80% activity is observed. Homodimer. Repressed by MhqR. Induced by thiol specific stress conditions, such as exposure to 2-methylhydroquinone (2-MHQ), catechol or diamide. Not induced by oxidative stress due to hydrogen peroxide or methylglyoxal. Deletion mutant is sensitive to 2-MHQ and catechol. Belongs to the azoreductase type 1 family.