title: Determination of ascorbic acid with immobilized green zucchini ascorbate oxidase.
abstract: Ascorbate oxidase from zucchini squash was immobilized onto CH-Sepharose via carbodiimide. The properties of the immobilized enzyme were found to be similar to those of the free ascorbate oxidase. The immobilized enzyme was utilized in a flow-through system equipped with a polarographic detector which monitors the oxygen depletion due to the reaction ascorbic acid + 1/2 O2----dehydroascorbic acid + H2O. This method, the response of which is linear between 3 X 10(-7) and 5 X 10(-4) M ascorbate, was utilized to measure the ascorbic acid in biological samples such as human plasma and fruit juices at a rate of about 60 determinations every hour with a standard deviation lower than 5%.
mesh_terms: D001204:Ascorbate Oxidase; D001205:Ascorbic Acid / Q000032:analysis* / Q000097:blood; D001628:Beverages / Q000032:analysis; D002957:Citrus / Q000032:analysis; D004800:Enzymes, Immobilized; D006801:Humans; D010088:Oxidoreductases; D010944:Plants / Q000201:enzymology
chemical_list: D004800:Enzymes, Immobilized; D010088:Oxidoreductases; D001204:Ascorbate Oxidase; D001205:Ascorbic Acid