Laccase

Laccase is a multicopper oxidase enzyme that transfers electrons from phenolic and related substrates to oxygen, producing water. Its copper centers enable oxidation without requiring hydrogen peroxide.

Multicopper oxidase: A family of enzymes that use multiple copper ions to oxidize substrates while reducing oxygen to water. Laccases belong to this enzyme family and share its copper-based oxygen-reduction machinery.
Copper protein: A protein that binds copper ions as structural components or participants in biological reactions. Laccase activity depends on copper ions coordinated within its protein structure.
Lignin: A complex aromatic polymer that strengthens plant cell walls and resists biological degradation. Laccases contribute to lignin modification and breakdown by lignin-degrading fungi.
Peroxidase: An enzyme that catalyzes oxidation reactions using hydrogen peroxide as an electron acceptor. Unlike peroxidases, laccase uses molecular oxygen directly and does not require hydrogen peroxide.
Type 1 copper protein: A copper protein whose blue copper center accepts electrons from a substrate. This center receives electrons during the first step of laccase catalysis.
Phenol: An aromatic compound with a hydroxyl group directly bonded to a benzene ring. Phenolic compounds are common laccase substrates because their oxidation forms stabilized radicals.
White-rot fungus: A fungus that decomposes lignin in wood, often leaving cellulose-rich material behind. Many white-rot fungi secrete laccases as part of their lignin-degrading enzyme systems.
Tyrosinase: A copper-containing enzyme that hydroxylates monophenols and oxidizes ortho-diphenols to quinones. Tyrosinase has defined monophenolase and diphenolase activities, unlike laccase’s broader oxidation profile.
Type 2 copper: A copper center that participates in oxygen binding and reduction in multicopper oxidases. It works with the type 3 copper pair at laccase’s oxygen-reducing site.
Molecular oxygen: The diatomic molecule O₂ that serves as the terminal electron acceptor in aerobic metabolism. Laccase uses oxygen as its electron acceptor and reduces it to water.

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