oksüdaasi

Oksüdaasi, or oxidases, are enzymes that catalyze oxidation–reduction reactions in which molecular oxygen (O2) serves as the final electron acceptor. In these reactions, electrons are transferred from a substrate to oxygen, producing hydrogen peroxide (H2O2) or water (H2O). Oxidases are a diverse subset of the oxidoreductase family and often rely on cofactors such as flavins, heme groups, or metal centers to shuttle electrons.

Examples of oxidases include cytochrome c oxidase (the terminal enzyme of the mitochondrial respiratory chain), glucose oxidase, xanthine oxidase, and monoamine oxidases. Some oxidases, like cytochrome c oxidase, donate electrons to the respiratory chain and form water, while others, such as glucose oxidase and xanthine oxidase, generate hydrogen peroxide as a byproduct during substrate oxidation. Plant enzymes such as polyphenol oxidases (tyrosinases) also fall into this category and participate in pigment formation and browning reactions.

Biological roles of oxidases are varied. In cellular respiration, certain oxidases drive the production of ATP by transferring electrons to oxygen. In metabolism, they participate in the catabolism of sugars, purines, and amines, and their activity can influence levels of reactive oxygen species. In plants and microbes, oxidases contribute to defense responses and wound signaling. Some oxidases have signaling or regulatory roles through the transient production of reactive oxygen species.

Applications of oxidases include industrial biocatalysis and biosensing. Glucose oxidase, for example, is used in glucose sensors to detect H2O2 or O2 consumption. Other oxidases are explored for detoxification, synthesis of value-added products, and food processing, where enzymatic browning or pigment formation is relevant.