Thioredoxinjärjestelmät

Thioredoxin reductase is an essential enzyme found in all living organisms, playing a crucial role in cellular redox homeostasis. It belongs to the family of flavoproteins, utilizing a redox-active disulfide bond within its active site to catalyze the reduction of thioredoxin. Thioredoxin itself is a small protein that acts as a reducing agent for a wide range of cellular targets, including other proteins, DNA, and lipids.

The primary function of thioredoxin reductase is to regenerate the reduced form of thioredoxin. In its oxidized state, thioredoxin contains an intramolecular disulfide bond. When thioredoxin reduces a target molecule, this disulfide bond is broken, forming two free sulfhydryl groups. Thioredoxin reductase then uses NADPH as a reducing power source to re-form the disulfide bond in thioredoxin, thereby returning it to its active, reduced state. This cycle is vital for maintaining the appropriate redox balance within the cell, which influences numerous cellular processes such as DNA synthesis, cell proliferation, and apoptosis. Dysregulation of the thioredoxin system has been implicated in various diseases, including cancer and neurodegenerative disorders.