Question

Activated neutrophils and macrophages (types of white blood cells) fight invading bacteria by releasing superoxide. These cells contain an NADPH oxidase that catalyzes the reaction:

2O₂+ NADPH --> 2O₂^-. + NADP⁺ + H⁺

Write the mechanism for this reaction showing all electrons on oxygens.

Answer 1

Phagocytosis Killing/ Degradation→
burst in oxygen use with increase of glycogenolysis, increased glucose oxidase (HMP shunt) and production of active oxygen metabolites as follows:

2O₂+ NADPH --> 2O₂^-. + NADP⁺ + H⁺
2H⁺ +O₂⁺ → H2O2

Myeloperoxidase

MPO produces hypochlorous acid (HOCl) from hydrogen peroxide (H2O2) and chloride anion (Cl-)

H2O2 + Cl- → HOCl

MPO independent killing

H2O2 + O2- --> OH + OH- +O2

OH- is a potent free radical

SOD

(2O2 - + 2 H+ → H2O2 + O2)