Oxidation of hydroquinone by both cellular and extracellular grapevine peroxidase fractions

• Published in: Biochimie Vol. 74; no. 2; pp. 143 - 148
• Main Authors: Zapata, J.M., Caldéron, A.A., Muñoz, R, Ros Barceló, A.
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.02.1992
• Subjects: Ampyrone - metabolism; benzoquinone; Benzoquinones - metabolism; BIOCHEMISTRY; BIOCHIMIE; BIOQUIMICA; CELL CULTURE; Cells, Cultured; COMPOSE PHENOLIQUE; COMPUESTOS FENOLICOS; CULTIVO DE CELULAS; CULTURE DE CELLULE; grapevine; Hydrogen Peroxide - metabolism; Hydrogen-Ion Concentration; hydroquinone oxidation; Hydroquinones - metabolism; Isoelectric Focusing; Isoenzymes - metabolism; Kinetics; OXIDACION; OXIDATION; Oxidation-Reduction; OXYDATION; PEROXIDASAS; peroxidase; Peroxidase - metabolism; PEROXIDASES; PEROXYDASE; PHENOLIC COMPOUNDS; Plants - enzymology; VITIS VINIFERA; AAP; hydroquinone oxidation; benzoquinone; MN; peroxidase; grapevine; BQ
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/0300-9084(92)90038-G

The oxidation of hydroquinone by two peroxidase (EC 1.11.1.7) fractions obtained from the cells and spent medium of cell cultures of grapevine ( Vitis vinifera cv Monastrell) has been studied, and their comparative efficacy ( k cat / K Mratio) studied in both the H 2O 2-consuming and hydroquinone-consuming reactions. While the efficacy in the H 2O 2-consuming reaction is practically identical for both enzyme fractions, the cellular peroxidase has five-fold more efficacy in the hydroquinone-consuming reaction than the peroxidase located in the spent medium. Screening of cellular peroxidases capable of oxidizing hydroquinone on polyacrylamide gels, by means of a staining reaction based on the nucleophilic attack of 4-aminoantipyrine on p-benzoquinone in acidic media, reveals that all the cellular peroxidase isoenzymes are capable of oxidizing hydroquinone, probably yielding a quinone-diimine as a product of the staining reaction. Since isoperoxidases found in cellular fractions are also present in the spent medium, the values found for the different efficacies in the hydroquinone-consuming reaction must be considered as the results of the different proportions in which each peroxidase isoenzyme was found in the two fractions. The localization of a benzoquinone-generating system of high efficacy inside the plant cell, and probably located in vacuoles, is discussed with respect to the harmful role which the quinone/semiquinone pair might play in cell death, as part of the hypersensitive response expressed within the mechanism of plant disease resistance.