title: Influence of pH, benzoic acid, glutathione, EDTA, 4-hexylresorcinol, and sodium chloride on the pressure inactivation kinetics of mushroom polyphenol oxidase.
abstract: Pressure inactivation of mushroom PPO was studied for pH values ranging from 4 to 8, and the effect of some antibrowning agents on the pressure stability of mushroom PPO at pH 6.5 was evaluated. pH reduction below 6.5 resulted in a lowered inactivation threshold pressure and an increase of the absolute value of the activation volume (or a decrease of the z(p) value), the latter two parameters reflecting the pressure dependency of the inactivation rate constant. An increase in pH from 6.5 to 8, on the other hand, did only marginally affect the pressure stability of the enzyme. Mushroom PPO at pH 6.5 was markedly sensitized toward pressure by the presence of 2.5 mM 4-hexylresorcinol and slightly stabilized by the presence of 5 mM EDTA. The presence of 5 mM glutathione, sodium chloride, or benzoic acid caused no significant alteration of the enzyme pressure stability. Only in the presence of 4-hexylresorcinol, significant changes of the activation volume and z(p) value were noticed.
authors.affiliation: Department of Food and Microbial Technology, Faculty of Agricultural and Applied Biological Sciences, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Leuven, Belgium.
authors.forename: C A
authors.initials: CA
authors.lastname: Weemaes
authors.forename: L R
authors.initials: LR
authors.lastname: Ludikhuyze
authors.forename: I
authors.initials: I
authors.lastname: Van den Broeck
authors.forename: M E
authors.initials: ME
authors.lastname: Hendrickx
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D019817:Benzoic Acid / Q000494:pharmacology; D004156:Catechol Oxidase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D004795:Enzyme Stability; D005978:Glutathione / Q000494:pharmacology; D006604:Hexylresorcinol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011312:Pressure; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D012965:Sodium Chloride; D019817:Benzoic Acid; D004492:Edetic Acid; D004156:Catechol Oxidase; D005978:Glutathione; D006604:Hexylresorcinol