Occurrences, Physical and Biochemical Properties of Laccase

Laccases (benzenediol: oxygen oxidoreductase, EC 1.10.3.2) are multicopper oxidases that are widely distributed among plants, insects, and fungi. They belong to a group of polyphenol oxidases containing copper atoms in the catalytic centre which are usually called multicopper oxidases. It utilizes molecular oxygen to oxidize various aromatic and non-aromatic compounds. They have been described in different genera of ascomycetes, some deuteromycetes, and mainly in basidiomycetes. The enzyme catalyze the one electron oxidation of a wide variety of organic and inorganic substrates, including mono-diand polyphenols, amino-phenols, methoxyphenols, aromatic amines, and ascorbate, with the concamitant four electron reduction of oxygen to water. Laccases are found in Prokaryotes and Eukaryotes. Laccase is localized both intracellular and extracellular fraction. In addition to the general inhibitors a very wide range of compounds are known to inhibit laccase. Fungal laccases typically exhibit pH optima in the acidic pH range and stable at temperature between 30-50°C, and isoeletric points (pI) ranging between 3 to 7. Km ranges from 10s of mM for syringaldazine and ABTS to 100 s of mM for DMP and guaiacol. Their importance in the synthesis and biodegradation of lignin remains an intensively studied subject and the biotechnological aspects of these enzymes seems to be just beginning. This review helps to understand the properties of this important enzyme for efficient utilization for its biotechnological and environmental applications.