Respiratory burst is due to which enzyme -

Ans. is 'a' i.e., NADPH oxidase Respiratory Burst o To deal with microbial infection, phagocytes produce toxic oxygen radical in a process known as a respiratory burst. The generation of reactive oxygen intermediates is due to activation of NADPH oxidaseQ o During phagocytosis, microbial killing is accomplished largely by oxygen-dependent mechanisms, o This oxygen-dependent killing is due to generation of reactive oxygen species (reactive oxygen intermediates). o The generation of reactive oxygen intermediates is due to rapid activation of an oxidase-NADPH oxidase, o This NADPH oxidase oxidizes NADPH and in the process, reduces oxygen to superoxide anion (O2-). o Superoxide anion is then converted into Hf), by spontaneous dismutation. o H2O2, can be further reduced to the highly reactive hydroxyl radicle (OH). o H2O2 generated by NADPH oxidase system is generally not able to efficiently kill microbes itself, o However, the azurophilic granules of neutrophils contain the enzyme myeloperoxidase (MPO), which in the presence of a halide such as C1-, convertes H2O2 to hypochlorite (HOCl). o Hypochlorite is a potent antimicrobial agent that destroys microbes by halogenation or by oxidation of protein & lipids. o The H2O2 - MPO - halide system is the most efficient bactericidal system in neutrophils.