Laccase

Laccases ( EC 1.10.3.2 ) are copper-containing, "blue" enzymes that are found in many plants, fungi and microorganisms. The first laccase was isolated in 1883 from the sap of the Japanese lacquer tree ( Rhus vernicifera ). Hence the name laccase was chosen for this enzyme. Eukaryotes and prokaryotes were the laccases in the biological domains demonstrated; they are ubiquitous in white rot fungi, but also occur in woody plants, where they are involved in the Ligninsynthese, as in some insects (eg wasps venom) and bacteria ( eg Bacillus subtilis). Laccases catalyze the oxidation of phenolic substances coupled with the reduction of oxygen. The phenol group is oxidized to a radical, while the oxygen is reduced to water:

Laccases belong to the most oxidoreductases, due to their substrate specificity, they are also referred to as monophenol. The catalytically active center contains four copper ions, which can be distinguished according to their spectroscopic properties. The "blue" type 1 copper is involved in substrate oxidation, a type 2 - and two type 3 copper ions form a trinuclear cluster that binds oxygen and reduced to water. The first crystal structure of a laccase was published in 2002, this originates from the fungus Trametes versicolor.

Active laccases can be easily detected because they are able to oxidize the chromogenic substrates ABTS, syringaldazin and guaiacol.

Laccases can be used industrially for bleaching pulp in the paper industry the bleaching of textile dyes, in the production of wine corks, and in other applications.