The study of superparamagnetic nanoparticle-supported lipase
Abstract: The content of immobilization of enzyme was introduced ,including conceptions，preparation methods and properties .There are many limitations in application of free enzyme. So in this paper, immobilization of lipase was studied. Superparamagnetic nanoparticles were first immobilized with 3-aminopropyltriethoxysilane.Then glutaraldehyde was employed as a linker to the lipase to the surface of nanoparticles to form Iron Oxide-lipase. The lipase can catalyze the chiral resolution with high selectivity. To determine the effection of immobilization, the selectively transesterification of racemic 2-bromopropionic acid, 2-chlorinpropionic acid, 2-bromocaproic acid was taken as model reaction. The reaction equation was as follows:
Average isolation yields of 76% and 80% ware obtained for R-butyl esters and the yields of 78% and 82% ware obtained for S-carboxylates, respectively. The ee value of isolated R-butyl esters and S-carboxylates were usually higher than 99%. In a typical experiment, to determine the possibility of recycling the nanoparticle-supported lipase for repeated uses, racemic 2-bromopropionic acid was chosen as model reaction. The conversion percentages dropped from 29% to 20% after four reaction cycles for Iron Oxide-lipase. In comparison, the free lipase demonstrated much higher enzymatic activity with a conversion yield of 55% in the first round reaction. However, the catalytic activity of the free enzyme decreased rapidly from 55% to 7% in the second reaction cycle. It completely lost its enzymatic activity in its third and fourth rounds of reaction.
Keywords：Superparamagnetic nanoparticles; lipase; immobilization; transesterification
