Purification of two peroxidase isoenzymes of Aloe barbadensis which oxidize p-coumaric acid

• Published in: Plant physiology and biochemistry 2002-02, Vol.40 (2), p.127-132
• Main Authors: Esteban-Carrasco, Alberto, Zapata, José Miguel, López-Serrano, Matías, Sabater, Bartolomé, Martín, Mercedes
• Format: Article
• Language: English
• Subjects: ACIDE COUMARIQUE; ACIDOS CUMARICOS; Agronomy. Soil science and plant productions; ALOE BARBADENSIS; Analytical, structural and metabolic biochemistry; Biological and medical sciences; COUMARIC ACIDS; DRUG PLANTS; Economic plant physiology; Enzymes; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydroquinone; Metabolism; Nutrition. Photosynthesis. Respiration. Metabolism; Oxidoreductases; p-coumaric acid; PEROXIDASAS; Peroxidase; PEROXIDASES; PEROXYDASE; Plant physiology and development; PLANTAS MEDICINALES; PLANTE MEDICINALE; PURIFICACION; PURIFICATION; Reactive oxygen species
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/S0981-9428(01)01355-9

Using a combination of hydrophobicity and ion-exchange chromatography methods, one cationic (p I 9.0) and one anionic (p I 4.5) peroxidase (donor: hydrogen-peroxide oxidoreductase; EC 1.11.1.7) isoenzymes of Aloe barbadensis have been purified (the cationic peroxidase to homogeneity as judged by SDS-PAGE analysis and microsequencing). This allowed us to initiate the investigation of individual catalytic properties to be related to their respective functions in vivo. The two peroxidases have an optimal activity at pH 6.0. Apparent affinities for H 2O 2 range between 0.01 and 0.14 mM depending on the phenolic substrate and the isoenzyme. The apparent K m values for the phenolics ( p-coumaric acid and hydroquinone) are some 25-fold lower in the anionic (around 0.02 mM) than in the cationic (around 0.77 and 0.34 mM, respectively) isoenzyme. The possible functions of the activities are discussed.