GLUCOSE-OXIDASE AND OTHER ENZYMES OF HYDROGEN-PEROXIDE METABOLISM FROM CUTICLE OF SCHISTOCERCA-AMERICANA-GREGARIA

Extracts of locust cuticle contain glucose oxidase. The enzyme was specific for the oxidation of β-d-glucopyranose to d-gluconate, probably via d-glucono-1,5-lactone. Oxygen was required for the reaction and hydrogen peroxide was generated in amounts stoichiometric with the gluconate formed. The enzyme had a Km for glucose of 28 mM and a pH optimum of 6.5. Other enzymes present in extracts of locust cuticle included peroxidase, catalase and superoxide dismutase. The activity of glucose oxidase in locust cuticle increased during the first few days of adult life and thereafter remained constant, whereas in haemolymph the activity of the enzyme reached a peak after 4-5 days and then decreased. The proposed role for glucose oxidase in cuticle is to generate hydrogen peroxide. This may then function as an oxidizing agent for sclerotization reactions or may act as an antibacterial agent. © 1979.