%0 Journal Article %T Immobilization of a Commercial Lipase from Penicillium camembertii (Lipase G) by Different Strategies %A Adriano A. Mendes %A Larissa Freitas %A Ana Karine F. de Carvalho %A Pedro C. de Oliveira %A Heizir F. de Castro %J Enzyme Research %D 2011 %I Hindawi Publishing Corporation %R 10.4061/2011/967239 %X The objective of this work was to select the most suitable procedure to immobilize lipase from Penicillium camembertii (Lipase G). Different techniques and supports were evaluated, including physical adsorption on hydrophobic supports octyl-agarose, poly(hydroxybutyrate) and Amberlite resin XAD-4; ionic adsorption on the anionic exchange resin MANAE-agarose and covalent attachment on glyoxyl-agarose, MANAE-agarose cross-linked with glutaraldehyde, MANAE-agarose-glutaraldehyde, and epoxy-silica-polyvinyl alcohol composite. Among the tested protocols, the highest hydrolytic activity (128.2 ¡À 8.10£¿IU¡¤g£¿1 of support) was achieved when the lipase was immobilized on epoxy-SiO2-PVA using hexane as coupling medium. Lipase immobilized by ionic adsorption on MANAE-agarose also gave satisfactory result, attaining 55.6 ¡À 2.60£¿IU¡¤g£¿1 of support. In this procedure, the maximum loading of immobilized enzyme was 9.3£¿mg¡¤g£¿1 of gel, and the highest activity (68.8 ¡À 2.70£¿IU¡¤g£¿1 of support) was obtained when 20£¿mg of protein¡¤g£¿1 was offered. Immobilization carried out in aqueous medium by physical adsorption on hydrophobic supports and covalent attachment on MANAE-agarose-glutaraldehyde and glyoxyl-agarose was shown to be unfeasible for Lipase G. Thermal stability tests revealed that the immobilized derivative on epoxy-SiO2-PVA composite using hexane as coupling medium had a slight higher thermal stability than the free lipase. 1. Introduction Lipases (triacylglycerol acyl hydrolases EC 3.1.1.3) are hydrolases that act on carboxylic ester bonds. The natural physiologic role of lipases is the hydrolysis of triglycerides into fatty acids and glycerol, but they can also catalyze esterifications and interesterifications in nonaqueous media [1¨C5]. A peculiarity mechanism action of lipases is the interfacial activation. Most lipases have a ¦Á-helical oligopeptide structure covering their active site (lid or flap) and making them inaccessible to substrates. In the absence of a hydrophobic interface, the active site is secluded from the reaction medium, and the enzyme is in the so-called ¡°closed conformation.¡± However, in the presence of a hydrophobic interface (a drop of oil), the lipase changes its conformation and exposes the catalytic site to the hydrophobic phase, yielding the ¡°open conformation¡± [6¨C9]. The limitations of the industrial use of lipases have been mainly due to their high cost, which may be overcome by immobilization techniques on solid supports. Immobilization facilitates the separation of products and provides more flexibility with enzyme/substrate contact by %U http://www.hindawi.com/journals/er/2011/967239/