ossidasi

Ossidasi, or oxidases in English, are a broad class of enzymes that catalyze oxidation–reduction reactions in which molecular oxygen (O2) serves as the terminal electron acceptor. In many oxidases, electrons are transferred from a substrate to O2, producing hydrogen peroxide (H2O2) or water (H2O) as byproducts. Some oxidases that participate in cellular respiration reduce O2 directly to water as part of the electron transport chain. The term is sometimes contrasted with oxygenases, which incorporate oxygen atoms into substrates.

Most oxidases depend on cofactors such as flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN), heme groups, or copper ions to shuttle electrons. These cofactors enable the enzyme to accept electrons from the substrate and pass them to O2. Oxidases are found across biology, from microorganisms to animals, and play roles in energy production, metabolism, and protective responses.

Representative examples include cytochrome c oxidase (complex IV of the mitochondrial respiratory chain), which reduces O2 to water; glucose oxidase and lactate oxidase, used in food processing and biosensors and typically producing H2O2; xanthine oxidase, which oxidizes purines to uric acid with H2O2 formation; and monoamine oxidases, which degrade neurotransmitters by transferring electrons to O2. Multicopper oxidases and other oxidases also participate in pigment formation, lignin breakdown, and environmental detoxification.

Applications of oxidases span medicine, biochemistry, and industry, including diagnostic assays, biosensors for glucose and other analytes, and industrial biocatalysis. In microbiology, oxidase tests help identify bacteria based on their terminal oxidase activity.