Photochemical Immobilization of Cucurbita Fruit Ascorbate Oxidase onto Polyethylene Disc for Determination of Ascorbate in Serum and Foodstuffs

Abstract

Abstract: An ascorbate oxidase purified from the green fruit of zucchini squash (Cucurbita pepo medullosa) was immobilized photochemically on a polyethylene disc with 85% retention of initial activity of free enzyme. The optimum pH (5.5) was unchanged, while K_m was decreased. The polyethylene discs were employed for determination of ascorbic acid in serum and foodstuffs. The working linear range was 2.8 μM to 16 μM. The mean value of ascorbic acid in serum as measured by the method was 0.16 mg/dl in males and 0.209 mg/dl in females. The immobilized enzyme was used 100 times over 4 months, when stored at 4°C.

Keywords::

• ascorbate
• ascorbate oxidase
• photoimmobilization
• polyethylene disc
• serum
• foodstuff

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper