Chalmers University of Technology, Department of Chemical and Biological Engineering, Gothenburg, Sweden.
Colloids Surf B Biointerfaces. 2012 Dec 1;100:22-30. doi: 10.1016/j.colsurfb.2012.04.042. Epub 2012 May 24.
Immobilization of enzymes usually improves the recyclability and stability and can sometimes also improve the activity compared to enzymes free in solution. Mesoporous silica is a widely studied material as host for immobilized enzymes because of its large internal surface area and tunable pores. It has previously been shown that the pore size is critical both for the loading capacity and for the enzymatic activity; however, less focus has been given to the influence of the particle size. In this work the effect of particle size and particle morphology on the immobilization of lipase from Mucor miehei and Rhizopus oryzae have been investigated. Three kinds of mesoporous silica, all with 9 nm pores but with varying particle size (1000 nm, 300 nm and 40 nm) have been synthesized and were used as host for the lipases. The two lipases, which have the same molecular size but widely different isoelectric points, were immobilized into the silica particles at varied pH values within the interval 5-8. The 300 nm particles were proven to be the most suitable carrier with respect to specific activity for both enzymes. The lipase from M. miehei was more than four times as active when immobilized at pH 8 compared to free in solution whereas the difference was less pronounced for the R. oryzae lipase.
酶的固定化通常可以提高酶的可回收性和稳定性，有时还可以提高酶的活性，与游离在溶液中的酶相比。介孔硅由于其较大的内表面积和可调节的孔而被广泛研究作为固定化酶的宿主。以前已经表明，孔径对于负载能力和酶活性都是至关重要的；然而，对于粒径的影响关注较少。在这项工作中，研究了粒径和颗粒形态对米根霉脂肪酶和米根霉脂肪酶固定化的影响。合成了三种具有 9nm 孔径但粒径不同（1000nm、300nm 和 40nm）的介孔硅，并将其用作脂肪酶的宿主。这两种脂肪酶具有相同的分子大小，但等电点差异很大，在 pH 值为 5-8 的范围内，在不同的 pH 值下被固定在二氧化硅颗粒中。对于两种酶，300nm 颗粒在比活方面都是最适合的载体。与游离在溶液中的酶相比，在 pH 值为 8 时固定化的米根霉脂肪酶的活性提高了四倍以上，而米根霉脂肪酶的差异则不那么明显。
