title: Purification and biochemical characterization of polyphenol oxidases from embryogenic and nonembryogenic cotton (Gossypium hirsutum L.) cells.
abstract: Polyphenol oxidases (PPOs) were isolated from cell suspensions of two cultivars of cotton (Gossypium hirsutum L.), and their biochemical characteristics were studied. PPO from Coker 312, an embryogenic cultivar, showed a highest affinity to catechol 20 mM, and PPO from R405-2000, a nonembryogenic cultivar, showed a highest affinity to 4-methylcatechol 20 mM. The optimal pH for PPO activity was 7.0 and 6.0 for Coker 312 and R405-2000, respectively. The enzyme had an optimal temperature of 25 degrees C and was relatively stable at 20-30 degrees C. Reducing sodium metabisulfite, ascorbic acid, dithiothreitol, SnCl(2), and FeCl(3) markedly inhibited PPO activity, whereas its activity was highly enhanced by Mg(2+), Ca(2+), and Mn(2+) and was moderately inhibited by Ba(2+), Cu(2+), and Zn(2+). The analysis revealed a single band on the sodium dodecyl sulfate polyacrylamide gel electrophoresis which corresponded to a molecular weight of 55 kDa for Coker 312 and 42 kDa for R405-2000.
authors.affiliation: Groupe d'Etude des Substances Végétales à Activités Biologiques, Institut des sciences de vigne et du Vin, UFR des Sciences Pharmaceutiques, Université de Bordeaux 2, 146 rue Léo-Saignat, 33076 Bordeaux cedex, France.
authors.forename: Tanoh Hilaire
authors.initials: TH
authors.lastname: Kouakou
authors.forename: Yatty Justin
authors.initials: YJ
authors.lastname: Kouadio
authors.forename: Patrice
authors.initials: P
authors.lastname: Kouamé
authors.forename: Pierre
authors.initials: P
authors.lastname: Waffo-Téguo
authors.forename: Alain
authors.initials: A
authors.lastname: Décendit
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Mérillon
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D004156:Catechol Oxidase / Q000378:metabolism*; D002396:Catechols / Q000378:metabolism; D002712:Chlorides; D003300:Copper / Q000494:pharmacology; D004229:Dithiothreitol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005290:Ferric Compounds / Q000494:pharmacology; D003368:Gossypium / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D013447:Sulfites / Q000378:metabolism; D013696:Temperature; D017971:Tin Compounds / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
chemical_list: D002396:Catechols; D002712:Chlorides; D004791:Enzyme Inhibitors; D005290:Ferric Compounds; D013447:Sulfites; D017971:Tin Compounds; C018599:4-methylcatechol; C023599:stannous chloride; D001464:Barium; D008345:Manganese; C005200:sodium metabisulfite; D003300:Copper; D004156:Catechol Oxidase; D008274:Magnesium; D015032:Zinc; D001205:Ascorbic Acid; D002118:Calcium; D004229:Dithiothreitol; C024555:ferric chloride