Purification and characterization of an ascorbate peroxidase from potato tuber mitochondria

• Published in: Plant physiology and biochemistry Vol. 38; no. 10; pp. 773 - 779
• Main Authors: De Leonardis, Silvana, Dipierro, Nunzio, Dipierro, Silvio
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 2000; Elsevier
• Subjects: Agronomy. Soil science and plant productions; ascorbate; ascorbate peroxidase; Biological and medical sciences; CHEMICOPHYSICAL PROPERTIES; Economic plant physiology; Enzymes; Fundamental and applied biological sciences. Psychology; HORTALIZAS (PLANTAS); Metabolism; MITOCHONDRIA; MITOCHONDRIE; MITOCONDRIA; Nutrition. Photosynthesis. Respiration. Metabolism; PEROXIDASAS; PEROXIDASES; PEROXYDASE; Plant physiology and development; PLANTE LEGUMIERE; PROPIEDADES FISICOQUIMICAS; PROPRIETE PHYSICOCHIMIQUE; reactive oxygen species; SOLANUM TUBEROSUM; VEGETABLE CROPS; NEM, N-ethylmaleimide; ascorbate peroxidase; p-HMB, p-hydroxymercuribenzoate; Solanum tuberosum; mitochondria; AsA, ascorbic acid or ascorbate; AFR, ascorbate-free radical; SOD, superoxide dismutase; mAPX, mitochondrial ascorbate peroxidase; reactive oxygen species; ascorbate; ROS, reactive oxygen species; DHA, dehydroascorbate; cAPX, cytosolic ascorbate peroxidase; APX, ascorbate peroxidase; Purification; Enzyme; L-Ascorbate peroxidase; Characterization; Mitochondria; Enzymatic activity; Peroxidases; Dicotyledones; Angiospermae; Tuber; Spermatophyta; Oxidoreductases; Tuber plant; Solanaceae; Catalyst activity
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/S0981-9428(00)01188-8

Ascorbate peroxidase (APX) has been purified from potato tuber ( Solanum tuberosum L.) mitochondria. The potato enzyme appeared to be localized inside mitochondria. The mitochondrial APX was purified to homogeneity and its physico-chemical and kinetic properties were compared with those of the cytosolic enzyme. The molecular mass of mAPX was 31 kDa, as estimated by SDS-PAGE, and was similar to that of the cytosolic enzyme, but its relative mobility in non-denaturing PAGE was different from the cytosolic APX. The K m values of mAPX for AsA and H 2O 2 were 76.1 ± 23.1 and 80.3 ± 24.9 μM, respectively, and were higher than those of the cytosolic enzyme. Mitochondrial APX was sensitive to inhibition by sulfhydryl reagents, such as mersalyl and p-hydroxymercuribenzoate (p-HMB). A role for the mitochondrial ascorbate-ascorbate peroxidase system in the scavenging of toxic oxygen species inside potato tuber mitochondria is proposed.