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Abstract: 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 (V max and K m) 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. [Copyright &y& Elsevier]

Abstract: Candida rugosa lipase was immobilized by covalent binding on hybrid matrix of polysiloxane–polyvinyl alcohol chemically modified with different activating agents as glutaraldehyde, sodium metaperiodate and carbonyldiimidazole. The experimental results suggested that functional activating agents render different interactions between enzyme and support, producing consequently alterations in the optimal reaction conditions. Properties of the immobilized systems were assessed and their performance on hydrolytic and synthetic reactions were evaluated and compared with the free enzyme. In hydrolytic reactions using p-nitrophenyl palmitate as substrate all immobilized systems showed higher thermal stability and optima pH and temperature values in relation to the free lipase. Among the activating compounds, carbonyldiimidazole resulted in a total recovery of activity on the support and the highest thermal stability. For the butyl butyrate synthesis, the best performance (molar conversion of 95% and volumetric productivity of 2.33gL−1 h−1) was attained with the lipase immobilized on POS–PVA activated with sodium metaperiodate. The properties of the support and immobilized derivatives were also evaluated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopies and chemical composition (FTIR). [Copyright &y& Elsevier]