Marja-Leena Niku-Paavola

Laccase — a Useful Enzyme for Modification of Biopolymers

Laccases are an interesting group of multi-copper enzymes, which have potential within various applications. They have surprisingly broad substrate specificities and can oxidize simple diphenols, polyphenols, diamines, and aromatic amines. Laccases oxidize their substrates by a one-electron transfer mechanism. Molecular oxygen is used as an electron acceptor. The substrate loses a single electron and usually forms a free radical. Laccases are widely distributed in nature. The best known laccase producers are from fungal origin. They have several functions in nature e.g. are involved in both polymerisation and de-polymerisation processes of lignin. Laccases have been used successfully in bioglueing of lignocellulose material in order to produce lignocellulose based composites, like fibre or particle boards. Promising results with laccases have also been achieved in grafting reactions. Oxidation of biopolymer substrates such as starch or cellulose has been carried out with laccases combined with mediators.