Immobilization and catalytic properties of lipase on chitosan for hydrolysis and esterification reactions

Abstract

-The objective of this study was to evaluate the immobilization of lipase on a chitosan support by physical adsorption, aiming at its application in hydrolytic and synthetic reactions. Two types of chitosan (flakes and porous) were used for immobilizing lipase from a microbial source (Candida rugosa) and animal cells (porcine pancreas). The best results for recovery of total activity after immobilization were obtained for microbial lipase and porous chitosan beads. This set was selected for further immobilization studies, including full characterization of the immobilized derivative in aqueous and organic media. In aqueous medium, the operational and thermal stabilities of this preparation were quantified. In organic medium, the direct synthesis of n-butyl butyrate in organic solvent was chosen as a model reaction. The influence of several parameters, such as temperature, initial butyric acid concentration and amount of enzyme in the reaction system, was analyzed. Production of n-butyl butyrate was optimized and an ester yield response equation was obtained, making it possible to predict ester yields from known values of the three main factors. Use of this immobilized preparation was extended to the direct esterification of a large range of carboxylic acids (from C 2 to C 12 ) with a variety of alcohols (from C 2 to C 10 ).

Determinação das propriedades catalíticas em meio aquoso e orgânico da lipase de Candida rugosa imobilizada em celulignina quimicamente modificada por carbonildiimidazol

“…Em meios ácidos, estes grupos ficam protonados e o ataque nucleofílico da serina no grupo carbonílico do substrato (triglicerídeo) pode comprometer a formação do complexo acil-enzima. Os grupos hidroxilas (-OH) presentes na estrutura do suporte possuem afinidade pelos hidrogênios ionizáveis (H + 21 , um suporte catiônico. Nesse caso, o suporte agiu no sentido de ter mais íons com carga negativa nas proximidades da enzima, deslocando o perfil atividade-pH da enzima imobilizada para valores inferiores a pH = 7,0.…”

“…Com relação ao somatório do número de carbonos dos materiais de partida, observa-se mais uma vez que para substratos com número superior a 14 carbonos, ocorre uma redução gradativa da conversão molar do substrato no éster correspondente 16,21 .…”

Seed lipases: sources, applications and properties - a review

“…The participation of lipases in the worldwide enzyme industry market has grown significantly and it is believed that, in the future, they will acquire importance comparable to that of the peptidases, which currently represent 25 to 40% of industrial enzyme sales (Hasan et al 2006). Lipases act, by definition, at the organic-aqueous interface, catalyzing the hydrolysis of estercarboxylate bonds and releasing fatty acids and organic alcohols (Pereira et al, 2003;Leal et al 2002;Kamimura et al, 1999;Merçon et al 1997). However, as Pottevin showed for the first time in 1906, in water-restricted environments, the reverse reaction (esterification) or even various transesterification reactions can occur Castilho 2008, Castro et al 2000).…”

Comparative performance of microbial lipases immobilized on magnetic polysiloxane polyvinyl alcohol particles

“…Esterification activity was expressed as µmol of formed butyl butyrate. g -1 .min -1 of the dry support (Pereira et al, 2003).…”