Question

Describe the action of NADPH-Oxidase. What reaction does it catalyze? What is/are its substrates and the product(s) of it's activity?

Answer 1

•There are following aspects of NADPH in human and plant :

•NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) is a multisubunit membrane-bound enzyme complex that faces the extracellular space. The enzyme comprising membrane and cytosolic components, which actively communicate during the host responses to a wide variety of stimuli, including viral and bacterial infections. It can be found in the plasma membrane as well as in the membranes of phagosomes used by neutrophil white blood cells to engulf microorganisms.

•NADPH oxidase is an enzyme, catalyzes the production of a superoxide free radical by transferring one electron to oxygen from NADPH.

•In plants NADPH is a cofactor, used to donate electrons and a hydrogens to reactions catalyzed by some enzymes. ... As in other reactions, NADPH helps carry electrons and protons driven by sunlight into new carbon-carbon bonds, creating sugar molecules

•NADPH oxidase catalyzes the production of a superoxide free radical by transferring one electron to oxygen from NADPH. During this process O2 is transported from the extracellular space to the cell interior and the H+ is exported.

•NADPH + 2O2 ↔ NADP+ + 2O2− + H+

•Structure of NADPH oxidase in the heart:- NADPH oxidase complex is composed of two major components. Plasma membrane spanning cytochrome b558 composed of p22phox and a Nox subunit (gp91phox (Nox2), Nox4) and cytosolic components composed of four regulatory subunits (p47 phox, p67 phox, p40 phox and Rac1). The low molecular weight G protein rac1 participates in assembly of the active complex. Upon activation, cytosolic components interact with cytochrome b558 to form an active NADPH oxidase enzyme complex, resulting in release of · O 2 − . The primary Nox subunit isoforms in cardiac . [see photo]

•One thing we should know that –

•NADPH oxidase (NOX) is a key player in the network of reactive oxygen species (ROS) producing enzymes. It catalyzes the production of superoxide (O2−), that in turn regulates a wide range of biological functions in a broad range of organisms. Plant Noxes are known as respiratory burst oxidase homologs (Rbohs) and are homologs of catalytic subunit of mammalian phagocyte gp91phox.