氨基化二氧化硅颗粒固定木瓜蛋白酶研究

采用正硅酸乙酯与N-(β-氨乙基)氨丙基三乙氧基硅烷在油包水形成的微胶囊中同步水解的方法，一步法制备了氨基化的二氧化硅颗粒，得到的颗粒粒径在0.3～0.5μm之间，平均大小为0.37μm, 氨基含量和颗粒大小可控，氨基含量高达56mmol/g。此颗粒经戊二醛处理后，采用共价法固定木瓜蛋白酶，固定化最适pH6.5，最佳给酶量为15mg/g载体，固定化酶的最适反应温度为70℃，最适反应pH为6.5，固定化酶热稳定性，pH耐受性，贮存稳定性都明显高于游离酶，表明此颗粒可作为一种优良的酶固定化载体。

Immobilization and Stabilization of Papain on SiO2 Particles Containing Amine Groups

Numerous approaches and materials have been explored for preparation of immobilization enzymes because they have considerable advantages over enzyme in bulk solution. Among present enzyme carriers inorganic materials have lower cost and more stability than organic materials. But the present inorganic materials contain less active sites and have to undergo some complicated processes before binding enzyme. So it is necessary to explore a new kind of inorganic enzyme carrier. Papain, a well characterized thiol protease kinetically and structurally, is a suitable model to compare the efficiency of various immobilization procedures. SiO2 particles containing amine groups were synthesized by synchronous hydrolysis of tetraethylorthosilicate (TEOS) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) in W/O Microemulsion of Triton X-100/cyclohexane/ammonium hydroxide system. The obtained particles have a diameter range from 0.3 microm to 0.5 microm, and their average size is 0.37 microm and can be controlled by adjusting water to surfactant molar ratio and water to TEOS and AEAPS molar ratio. Compared with traditional porous silica beads, these particles contain much more amine groups and their amine group content can be easily changed in the process of synthesis. Papain was immobilized on the particles which were treated by glutaraldehyde with covalent method. The optimum immobilization conditions of enzyme were as follows: enzyme load was 15 mg/g carrier, pH was 6.5. The pH and temperature optima were 6.5 and 70 degrees C for immobilized enzyme. All above indicate this kind of particle can be a good enzyme immobilization carrier.