peroksidaz

Peroksidaz are a family of enzymes that catalyze the reduction of hydrogen peroxide and organic peroxides, using various substrates as electron donors. They are heme-containing oxidoreductases and are widely distributed in living organisms, including plants, animals, fungi, and bacteria. Peroxidases participate in defense, lignin formation, pigment synthesis, and the removal of reactive oxygen species. They are distinguished from catalases, which primarily decompose hydrogen peroxide to water and oxygen.

Most peroxidases operate via a catalytic cycle that uses a heme prosthetic group. Hydrogen peroxide oxidizes the resting ferric enzyme to Compound I, a reactive high-valent iron species. Compound I then oxidizes substrates, forming substrate radicals and reducing to Compound II, which is subsequently restored to the resting ferric state by another substrate molecule.

Major families include plant peroxidases (such as class III peroxidases including horseradish peroxidase), animal peroxidases (myeloperoxidase and lactoperoxidase), and microbial peroxidases (catalase–peroxidases and dye-decolorizing peroxidases). Horseradish peroxidase is widely used in biochemistry and diagnostics; myeloperoxidase participates in immune defense by generating reactive oxidants.

Applications span analytical assays (ELISA, Western blot), biosensors, wastewater treatment, and polymerization of phenolic compounds. In nature they participate in lignin degradation, pigment formation, and antimicrobial defenses. Peroxidases exhibit diverse substrate ranges and optimal pH values, reflecting adaptation to their specific physiological roles.