Oxygen dependent killing is done through which of the following enzymes?: (A) NADPH oxidase, (B) Super oxide dismutase, (C) Catalase, (D) Glutathione peroxidase
Answer is A. Oxygen dependent killing is done through NADPH oxidase, which oxidases NADPH and reduces oxygen to superoxide anion. Superoxide is then conveed to hydrogen peroxide by spontaneous dismutation. In presence of chloride, myeloperoxidase in neutrophils can conve hydrogen peroxide to hypochlorous acid, which is bactericidal. Catalase, Superoxide dismutase and Glutathione peroxidase are free radical scavenging enzymes that break down hydrogen peroxide and superoxide anion. Ref: Pathologic Basis Of Disease, Robbins, 6th Edition, Page 62; 7th Edition, Page 60, 16.