Summary
Laccase (CAS 80498-15-3) is a copper protein with a molecular weight of approximately 120,000, featuring four copper atoms and susceptibility to inhibition by CN-. This enzyme exhibits the capability to oxidize polyphenols, facilitating the methylation of phenols and diamines. Oxygen substitution allows for the oxidation of a broad spectrum of substrates with structures akin to rho-polyphenols. Some fungal laccases can additionally oxidize monovalent phenols like cresol and ascorbic acid.
CAS number: 80498-15-3
Molecular formula: C9H13NO
Molecular weight: 151.2
EINECS number: 420-150-4
Reaction Mechanism:
Laccase functions as a single-electron oxidoreductase. The catalysis of oxidation reactions across various substrates involves the generation of substrate free radicals and the synergistic action of four copper ions within the laccase molecule. The substrate binds to the type I Cu2+ site in the enzyme's active center, transferring it to the trinuclear site through the Cys-His pathway. This site subsequently transfers electrons to the second substrate oxygen molecule bound to the active center, reducing it to water. The entire reaction process necessitates continuous single-electron oxidation to achieve full laccase reduction, followed by the transfer of reduced enzyme molecules to molecular oxygen through four-electron transfer. During this process, oxygen reduction may occur in two steps, generating a hydrogen peroxide intermediate that is further reduced to water with the involvement of two additional single electrons.
Industry Applications
Wine Industry:
Laccase acts as an adsorbent to selectively catalyze the oxidation of certain polyphenols, causing polymerization and subsequent removal through the clarification process.
No adverse changes in other sensory properties of wine occur, and laccase is stable in acidic media (suitable pH range: 2.5-4.0).
Used as a fining agent in conjunction with silica solution or polyvinylpyrrolidone, laccase proves more efficient than conventional clarification methods.
Recommended dosage: 5~500g enzyme per ton of raw materials, with adjustments based on the actual process.
Beer Industry:
Laccase is employed to remove oxygen at the end of the beer production process, extending beer storage time.
This method replaces the traditional process involving polyvinylpyrrolidone to remove polyphenols and subsequent removal of polyvinylpyrrolidone.
Juice Processing:
Laccase is used in the filtration process to improve flavor and color in juice, surpassing traditional methods using ascorbic acid and sulfate.
Aids in maintaining quality stability of juice drinks.
Baked Goods:
Laccase's ability to cross-link polymers enhances the mechanical strength, stability, and reduces stickiness of dough in baking.
Improves dough structure and increases the softness of baked products.