Laccase of Coriolus zonatus

Laccase is one of the lignolytic enzymes found in liquid cultures of the fungus Coriolus zonatus in defined medium. The enzyme was isolated from culture liquid and characterized. Laccase from C. zonatus is a single-chain protein with a molecular mass of 60 kDa. Carbohydrate moiety of enzyme consisted of mannose, galactose and N-acetyl-glucosamine in a ratio of 6:2:0.6, respectively, and comprised 10% of the entire molecule. Isoelectric point was detected at pH 4.6. Laccase was found to have a pH optimum of 4.9 and temperature optimum of 55 degree C. Substrate specificity studies were conducted with catechol, K-ferrocyanide, hydroquinone, and sinapinic acid as substrates. The highest efficiency of catalysis was observed with sinapic acid as the substrate. The kinetic constants k sub(cat) and K sub(m) of this reaction were 624 s super(-1) and 7 mu M, respectively.