Monooksygenaasi

Monooksygenaasi, also known as monooxygenase, is a class of enzymes that catalyzes monooxygenation reactions: it inserts one atom of molecular oxygen into an organic substrate while the other oxygen atom is reduced to water or, in some cases, hydrogen peroxide. These enzymes are distinct from dioxygenases, which incorporate both atoms of O2 into substrates.

The mechanism of action typically involves electron transfer from a reducing agent such as NADPH or NADH. Depending on the enzyme family, cofactors or prosthetic groups facilitate oxygen activation. The best-known families are cytochrome P450 monooxygenases (CYPs), which use a heme iron and receive electrons via P450 reductase; and flavin-containing monooxygenases (FMOs), which rely on flavin cofactors (FAD and FMN) within their reductase systems. Other monooxygenases include bacterial methane monooxygenase and various plant and fungal enzymes that participate in specialized metabolite biosynthesis.

Monooksygenaasi act on a wide range of substrates, including drugs and other xenobiotics, supporting phase I metabolism in pharmacology by introducing hydroxyl groups to increase solubility for excretion. They also participate in primary and secondary metabolism, contributing to the biosynthesis of hormones, fatty acids, terpenoids, alkaloids, and other natural products. In plants and microorganisms, monooxygenases enable diversification of chemical structures that underlie ecological interactions and defense.

Applications of monooxygenases span drug development, biocatalysis, and environmental bioremediation, where selective hydroxylation can simplify synthesis or degrade pollutants. Ongoing research aims to improve their activity, selectivity, and stability for industrial and therapeutic uses.