Kinetic and thermodynamic study of laccase cross-linked onto glyoxyl Immobead 150P carrier: Characterization and application for beechwood biografting

Abstract

In this study, we cross-linked aminated Thermothelomyces thermophilus laccase onto Immobead 150P epoxy carrier, and achieved an immobilization yield of 99.84 %. The optimum temperature and pH values for the oxidation of ABTS by laccase were determined to be 70 °C and pH 3.0. After 6 h at 50 °C, laccase activity was diminished by about 13 % in the free form and 28 %, in the immobilized form. K_m values for both free and cross-linked laccase were 0.051 and 0.567 mM, whereas V_max values were 2.027 and 0.854 μmol. min^-1, respectively. The immobilized laccase was able to preserve its full activity for 6 weeks, retaining approximately 95 % and 78 % of its initial activity after 8 and 20 weeks, respectively. The contact angles were two-fold higher when the laccase enzyme was occupied in the biografting reaction, revealing that the hydrophobic compound bonded stably onto beechwood samples.

Keywords: Biografting; Immobilization; Kinetics; Laccase; Wood hydrophobization.