title: Molecular and kinetic study of catalase-1, a durable large catalase of Neurospora crassa.
abstract: Catalase-1 (Cat-1), one of the two monofunctional catalases of Neurospora crassa, increases during asexual spore formation to constitute 0.6% of total protein in conidia. Cat-1 was purified 170-fold with a yield of 48% from conidiating cultures. Like most monofunctional catalases, Cat-1 is a homotetramer, resistant to inactivation by solvents, fully active over a pH range of 4-12, and inactivated by 3-amino-1,2,4-triazole. Unlike most monofunctional catalases, Cat-1 consists of 88 kDa monomers that are glycosylated with alpha-glucose and/or alpha-mannose, is unusually stable, and is not inactivated or inhibited by hydrogen peroxide. Cat-1 was more resistant than other catalases to heat inactivation and to high concentrations of salt and denaturants. Cat-1 exhibited unusual kinetics: at molar concentrations of hydrogen peroxide the apparent V was 10 times higher than at millimolar concentrations. Inactivation of Cat-1 activity with azide and hydroxylamine was according to first order kinetics, while cyanide at micromolar concentrations was a reversible competitive inhibitor.
authors.affiliation: Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, México, D.F., Mexico.
authors.forename: A
authors.initials: A
authors.lastname: Díaz
authors.forename: P
authors.initials: P
authors.lastname: Rangel
authors.forename: Y
authors.initials: Y
authors.lastname: Montes de Oca
authors.forename: F
authors.initials: F
authors.lastname: Lledías
authors.forename: W
authors.initials: W
authors.lastname: Hansberg
mesh_terms: D001386:Azides / Q000494:pharmacology; D002374:Catalase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D002384:Catalysis; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism; D006031:Glycosylation; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D019811:Hydroxylamine / Q000494:pharmacology; D007700:Kinetics; D046911:Macromolecular Substances; D008358:Mannose / Q000378:metabolism; D009492:Neurospora crassa / Q000201:enzymology*; D011489:Protein Denaturation
chemical_list: D001386:Azides; D004791:Enzyme Inhibitors; D046911:Macromolecular Substances; D019811:Hydroxylamine; D006861:Hydrogen Peroxide; D002374:Catalase; D005947:Glucose; D008358:Mannose