Transhydrogenase

Transhydrogenase is an enzyme that catalyzes the reductive transfer of a hydride ion from NADH to NADP+. This process is also known as hydride transfer. The enzyme is found in the inner mitochondrial membrane of eukaryotic cells, as well as in the plasma membrane of prokaryotic cells.

Function

Transhydrogenase plays a crucial role in maintaining the balance of NADH and NADPH in the cell. NADH is primarily involved in catabolic reactions, where it acts as an electron donor. On the other hand, NADPH is used in anabolic reactions, where it acts as an electron acceptor. By transferring a hydride ion from NADH to NADP+, transhydrogenase helps to ensure that the cell has an adequate supply of both types of coenzyme.

Structure

Transhydrogenase is a membrane protein that spans the inner mitochondrial or plasma membrane. It is composed of three subunits: dI, dII, and dIII. The dI and dII subunits form a proton channel that allows protons to flow across the membrane, while the dIII subunit binds NADH and NADP+ and catalyzes the hydride transfer reaction.

Clinical significance

Mutations in the gene encoding transhydrogenase can lead to a variety of metabolic disorders. For example, a deficiency in transhydrogenase activity can result in an imbalance of NADH and NADPH, which can disrupt cellular metabolism and lead to disease.

See also

• NADH
• NADP+
• Hydride transfer
• Metabolic disorders