RT Journal Article SR Electronic(1) A1 González, Celedonio A1 González, Gregorio A1 Avila, Julio A1 Pérez, M. Dolores A1 Brito, Nélida A1 Siverio, José M.YR 1994 T1 Nitrite causes reversible inactivation of nitrate reductase in the yeast Hansenula anomala JF Microbiology, VO 140 IS 10 SP 2633 OP 2637 DO https://doi.org/10.1099/00221287-140-10-2633 PB Microbiology Society, SN 1465-2080, AB The addition of nitrite, the product of the reaction catalysed by nitrate reductase, to cell suspensions of the yeast Hansenula anomalacaused a reversible inactivation of NADPH-dependent nitrate reductase activity. The haem- and Mo-dependent and Mo-dependent activities of nitrate reductase, determined with the non-physiological electron donors FMNH2and reduced methyl viologen respectively, were less affected. A similar inactivation was found with the proton ionophores 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. The inactive enzyme was found in the particulate fraction and cosedimented with the mitochondrial fraction. When the NADPH-dependent nitrate reductase activity was restored in vivothe enzyme was found in the soluble fraction. The inactivation of nitrate reductase by nitrite, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone was dependent on the external pH. The treatment of isolated mitochondria at alkaline pH with Triton X-100 solubilized about 30% of the inactive enzyme., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-140-10-2633