Evidence about the catecholoxidase activity of the enzyme ascorbate oxidase extracted from Cucurbita pepo medullosa.
Pure ascorbate oxidase (L-ascorbate:oxygen oxidoreductase, EC 1.10.3.3) isolated from Cucurbita pepo medullosa, which is known to be specific for ascorbic acid, shows a secondary catecholoxidase activity at approx. pH 6.7. This activity was tested against natural and synthetic compounds possessing a catechol-like structure. Among natural compounds (+)-catechin furnishes the same complex oxidation mixture obtained with other oxidases. Among synthetic compounds, 3,5-di-t-butylcatechol and 4-t-butylcatechol give the corresponding o-quinones. The significance of this secondary activity in the darkening process of fruits and vegetables which contain ascorbate oxidase is also discussed.
Evidence about the catecholoxidase activity of the enzyme ascorbate oxidase extracted from Cucurbita pepo medullosa. Pure ascorbate oxidase (L-ascorbate:oxygen oxidoreductase, EC 1.10.3.3) isolated from Cucurbita pepo medullosa, which is known to be specific for ascorbic acid, shows a secondary catecholoxidase activity at approx. pH 6.7. This activity was tested against natural and synthetic compounds possessing a catechol-like structure. Among natural compounds (+)-catechin furnishes the same complex oxidation mixture obtained with other oxidases. Among synthetic compounds, 3,5-di-t-butylcatechol and 4-t-butylcatechol give the corresponding o-quinones. The significance of this secondary activity in the darkening process of fruits and vegetables which contain ascorbate oxidase is also discussed.