Question

Which of the following helps in generating the oxygen (respiratory) burst in neutrophils?

• A. Superoxide dismutase
• B. NADPH oxidase
• C. Peroxidase
• D. Glutathione reductase

Hint:

Think of the enzyme that makes superoxide and whose defect causes chronic granulomatous disease.

Answer 1

The Correct Option is B

When a neutrophil engulfs a pathogen it triggers a sudden surge in oxygen consumption known as the respiratory or oxidative burst, whose purpose is to manufacture microbe-killing reactive oxygen species. The enzyme that ignites this burst is NADPH oxidase, a multi-subunit complex assembled on the phagosomal membrane that hands electrons from NADPH to oxygen and thereby generates the superoxide radical. From that superoxide the cell goes on to form hydrogen peroxide, and myeloperoxidase then converts peroxide and chloride into bactericidal hypochlorous acid. The competing options are not initiators: superoxide dismutase and glutathione reductase are protective enzymes that detoxify reactive species, and peroxidase operates only after peroxide has already been produced. The importance of NADPH oxidase is underscored clinically by chronic granulomatous disease, which results from its failure. Hence the enzyme responsible for generating the oxygen burst is NADPH oxidase. \[\boxed{\text{NADPH oxidase}}\]