hidroxilase

Hydroxylase, or hidroxilase in some languages, is an enzyme that catalyzes hydroxylation, the introduction of a hydroxyl group (-OH) into an organic substrate. These enzymes play roles in metabolism, collagen synthesis, neurotransmitter production, and detoxification. The general reaction requires molecular oxygen and often involves reducing equivalents such as NADPH, with electron transfer via flavin or iron-containing cofactors.

Two main classes exist: monooxygenases and dioxygenases. Monooxygenases insert one oxygen atom into the substrate while reducing the other to water; dioxygenases insert both atoms of molecular oxygen into the substrate. A major group of monooxygenases is the cytochrome P450 family, which metabolizes drugs and steroids in the endoplasmic reticulum and uses NADPH via associated reductases; other monooxygenases also employ heme or non-heme iron, flavins, or other cofactors.

Notable examples include phenylalanine hydroxylase (phenylalanine to tyrosine; requires tetrahydrobiopterin), tyrosine hydroxylase (tyrosine to L-DOPA; catecholamine synthesis), and tryptophan hydroxylase (tryptophan to 5-hydroxytryptophan; serotonin synthesis). Prolyl hydroxylases play essential roles in collagen maturation and cellular oxygen sensing. Oxygenases acting on lipids and steroids broaden the functional scope of the enzyme class. Biochemically, many hydroxylases rely on iron at the active site, with cofactors such as BH4, FMN, or FAD to shuttle electrons.

Biological significance is broad: hydroxylation modulates protein structure and function, enables neurotransmitter production, and facilitates xenobiotic metabolism and oxygen sensing. Cellular localization varies by enzyme family, including cytosol, mitochondria, and endoplasmic reticulum.