title: Interaction of purified alternative oxidase from thermogenic Arum maculatum with pyruvate.
abstract: Plant alternative oxidase (AOX) activity in isolated mitochondria is regulated by carboxylic acids, but reaction and regulatory mechanisms remain unclear. We show that activity of AOX protein purified from thermogenic Arum maculatum spadices is sensitive to pyruvate and glyoxylate but not succinate. Rapid, irreversible AOX inactivation occurs in the absence of pyruvate, whether or not duroquinol oxidation has been initiated, and is insensitive to duroquinone. Our data indicate that pyruvate stabilises an active conformation of AOX, increasing the population of active protein in a manner independent of reducing substrate and product, and are thus consistent with an exclusive effect of pyruvate on the enzyme's apparent V(max).
authors.affiliation: Biochemistry and Biomedical Sciences Division, School of Life Sciences, University of Sussex, Falmer, Brighton, UK.
authors.forename: J E
authors.initials: JE
authors.lastname: Carré
authors.forename: C
authors.initials: C
authors.lastname: Affourtit
authors.forename: A L
authors.initials: AL
authors.lastname: Moore
mesh_terms: D031058:Arum / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability / Q000187:drug effects; D006873:Hydroquinones; D007700:Kinetics; D024101:Mitochondrial Proteins; D010088:Oxidoreductases / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism* / Q000494:pharmacology; D000099188:Alternative Oxidase
chemical_list: D006873:Hydroquinones; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D019289:Pyruvic Acid; D000099188:Alternative Oxidase; C016421:duroquinol