Influence of the functional activating agent on the biochemical and kinetic properties of Candida rugosa lipase immobilized on chemically modified cellulignin

Candida rugosa lipase was immobilized by covalent binding on wood cellulignin (Eucaliptus grandis) chemically modified with different activating agents as carbonyldiimidazole, glutaraldehyde and sodium metaperiodate. The resulted immobilized derivatives were evaluated in both aqueous (hydrolysis) and organic (ester synthesis) media. In aqueous media a comparative study between free and immobilized derivatives was provided in terms of pH, temperature and kinetic constants (Vmax and Km) following the hydrolysis of p-nitrophenyl palmitate, in which new optima values were established. The experimental results suggested that functional activating agents render different interactions between enzyme and cellulignin, producing consequently alterations in the optimal reaction conditions. Different behavior was found when the immobilized derivatives were tested in organic media, under these conditions similar esterification activities were observed, independent on the agent used to active the immobilizing support. Reasons for this are discussed on the light of the interactions among the support, functional activating agent and lipase structure.