Laccase

Abstract

Abstract Laccases [EC 1.10.3.2, para‐bezenediol:dioxygen oxidoreductases] are multi‐copper proteins that oxidize various aromatic and non‐aromatic compounds by a radical‐catalyzed reaction mechanism using molecular oxygen as the secondary substrate. Laccase has a number of biological roles that include lignification, delignification, turnover of humic substances in soil and aquatic environments, pathogenicity, detoxification, morphogenesis, sporulation, growth and development of rhizomorphs, polymerization of melanin precursors and spore coat resistance. The ability of laccase to catalyze oxidation with only oxygen as a secondary substrate, its broad substrate range, and high catalytic constants have made it an appealing enzyme for a variety of remediative applications. These include bioremediation of phenolic‐rich wastewaters generated by paper and pulp, textile and dye, food and distillery industries as well as bioremediation of soils contaminated with recalcitrant xenobiotics such as chlorinated phenolic compounds, polycyclic aromatic hydrocarbons, explosives, endocrine‐disrupting chemicals, insecticides, fungicides, and herbicides. The enzyme's broad substrate spectrum, the use of readily available oxygen as the final electron acceptor, and no requirement for cofactors or peroxide have made it appealing for a variety of industrial applications in fields ranging from textile dyes, pulp and paper, biosensors, biofuel cells, chemical synthesis, beverage stabilisation, food products, and ethanol production. The advantages of laccase compared to other enzymes include relatively high yields, uncomplicated isolation from bulk fungal cultures, easy screening for specific producers with a broad substrate spectrum, a high degree of stability and activity especially after immobilization, and heterologous expression systems that have already been established. The characteristics of laccase allow for its potential utilization across a number of research areas, which will result in continued intensive investigations to better understand the enzyme and apply it forthe benefit of both humans and the environment.