title: Nitrite causes reversible inactivation of nitrate reductase in the yeast Hansenula anomala.
abstract: The addition of nitrite, the product of the reaction catalysed by nitrate reductase, to cell suspensions of the yeast Hansenula anomala caused 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 FMNH2 and 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 vivo the 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.
authors.affiliation: Dapartamento de Bioquímica y Biología Molecular, Universidad de La Laguna, Tenerife, Canarias, Spain.
authors.forename: C
authors.initials: C
authors.lastname: González
authors.forename: G
authors.initials: G
authors.lastname: González
authors.forename: J
authors.initials: J
authors.lastname: Avila
authors.forename: M D
authors.initials: MD
authors.lastname: Pérez
authors.forename: N
authors.initials: N
authors.lastname: Brito
authors.forename: J M
authors.initials: JM
authors.lastname: Siverio
mesh_terms: D019297:2,4-Dinitrophenol; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000187:drug effects / Q000378:metabolism*; D009573:Nitrites / Q000494:pharmacology; D010843:Pichia / Q000201:enzymology*
chemical_list: D004140:Dinitrophenols; D009573:Nitrites; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D019297:2,4-Dinitrophenol