| Abstract: | AbstractThe reaction kinetics of Candida antarctica lipase B (CalB) in the commercially available preparation Novozym® 435 (N435) were compared to those of preparations of CalB immobilised on Accurel® MP1000 (porous polypropylene). Two polypropylene preparations were made using enzyme loadings of 0.2% and 2% (w/w). All three preparations were used in hydrolysis as well as transesterification of two substrates, ethyl acrylate and ethyl methacrylate with octanol. Reactions carried out at water activity levels from 0.06 to 0.96 and at octanol concentrations between 25 and 500 mM showed that both water and octanol can inhibit CalB. Pronounced mass transfer limitations were also observed, which were more pronounced for N435 than for the two MP1000 preparations. The MP1000 preparations could thus use the lipase more efficiently in these reactions, achieving a specific activity (per g enzyme) between 5 and 20 times that of N435. To achieve high rates in the transesterification reaction, it is recommended to use low water activity and moderate alcohol concentration. In order to carry out a hydrolysis reaction, an intermediate water activity should be used to balance the effects of water as a limiting substrate and as a competitive inhibitor. |
