Evaluation of styrene-divinylbenzene beads as a support to immobilize lipases

A commercial and very hydrophobic styrene-divinylbenzene matrix, MCI GEL^® CHP20P, has been compared to octyl-Sepharose^® beads as support to immobilize three different enzymes: lipases from Thermomyces lanuginosus (TLL) and from Rhizomucor miehie (RML) and Lecitase ^® Ultra, a commercial artificial phospholipase. The immobilization mechanism on both supports was similar: interfacial activation of the enzymes versus the hydrophobic surface of the supports. Immobilization rate and loading capacity is much higher using MCI GEL^® CHP20P compared to octyl-Sepharose^® (87.2 mg protein/g of support using TLL, 310 mg/g using RML and 180 mg/g using Lecitase^® Ultra). The thermal stability of all new preparations is much lower than that of the standard octyl-Sepharose^® immobilized preparations, while the opposite occurs when the inactivations were performed in the presence of organic co-solvents. Regarding the hydrolytic activities, the results were strongly dependent on the substrate and pH of measurement. Octyl-Sepharose ^® immobilized enzymes were more active versus p-NPB than the enzymes immobilized on MCI GEL^® CHP20P, while RML became 700-fold less active versus methyl phenylacetate. Thus, the immobilization of a lipase on this matrix needs to be empirically evaluated, since it may present very positive effects in some cases while in other cases it may have very negative ones.