peroxidasecatalyzed

Peroxidase-catalyzed reactions are enzymatic oxidations in which a peroxidase enzyme uses hydrogen peroxide as the oxidant to transform a diverse set of substrates. In biology and biocatalysis, these reactions can involve phenolic compounds, amines, dyes, lignin-related substrates, and various organic molecules. Peroxidases play roles in plant defense, lignin biosynthesis, wound response, and microbial metabolism, among other processes.

Most heme-containing peroxidases operate via a catalytic cycle that begins when the resting ferric enzyme reacts with hydrogen peroxide to form Compound I, an iron(IV)-oxo species with a porphyrin radical. Compound I accepts electrons from substrates, forming Compound II and oxidized substrate radicals. A second electron transfer from substrate then regenerates the ferric enzyme and yields the oxidized product. This two-electron transfer mechanism underlies many of the enzyme’s oxidation reactions and explains the broad yet enzyme-specific substrate scope.

Key enzymes include horseradish peroxidase (HRP), soybean peroxidase, lactoperoxidase, and myeloperoxidase. They exhibit broad substrate tolerance but differ in kinetics, pH optima, and redox potential requirements. Peroxidases are widely used in analytical chemistry, especially in immunoassays and blotting, where HRP-labeled probes oxidize chromogenic or chemiluminescent substrates such as TMB, ABTS, and DAB to produce measurable signals.

Applications extend to biocatalysis, environmental remediation, and polymer chemistry, where controlled oxidation and coupling reactions are desirable. Limitations include sensitivity to hydrogen peroxide concentration, which can inactivate the enzyme at high levels, and substrate- or solvent-dependent activity and stability.