Kinetic differences of purified laccases from six Pleurotus ostreatus strains

Aims: Enzyme kinetics of purified laccases from six different Pleurorus ost reatus strains were determined in the oxidation of syringaldazine, guaiacol and ABTS. Methods and Results: Significant differences in the kinetic constants were found. Catalytic activity (k(cat)) ranged from 19 to 941 U mg(-1) for syrin galdazine, from 18 to 1565 U mg-l for ABTS, and from 4 to 44 U mg-l for gua iacol. The apparent affinity constants (K-M) also showed significant differ ences between the different strains, from 12 to 52 mu mol l(-1) for syringa ldazine, from 8 to 79 mu mol l(-1) for ABTS, and from 0.46 to 6.61 mmol l(- 1) for guaiacol. No differences were found either on the effect of increasi ng concentrations of organic solvent (acetonitrile) or on the activity pH p rofile. The temperature profile was the same for all the P. ostreatus strai ns, except for the IE8 strain, which seems to be more sensitive to temperat ure. The kinetic and stability data from the six P. ostreatus strains were also compared with those obtained from other white rot fungi, Coriolopsis g allica and Trametes versicolor, showing clear differences. Conclusions: The different P. ostreatus isolates show-ed different kinetic constants. Significance and Impact of the Study: The different enzymatic properties of laccases from various P. ostreatus strains should be considered for a pote ntial industrial or environmental application.