Design of fine particles of silicon polymer highly effective as entrapping gel for biocatalysts functioning in organic media

用溶胶-凝胶法将脂肪酶包埋在有机硅酸盐中，可以提高固定化制剂的酯化活性和热稳定性。有机改性硅酸盐是由四甲氧基硅烷(TMOS)和烷基有机硅烷的混合物制成的。在本研究中，我们尝试在W/O微乳液中或(2)在载体材料表面形成脂肪酶包埋凝胶，并对所得固定化脂肪酶的一些酶性质进行了研究。在丁酸合成酯的过程中，可以是异戊醇或(()sy+-)。(1)微乳液包埋法：在所考察的各种表面活性剂中，用Brij 97制备的硅酸盐包埋型脂肪酶在室温下表现出最高的催化活性。从TMOS和甲基三甲氧基硅烷的混合物中衍生出来的有机-无机杂化硅酸盐使固定化脂肪酶的活性得到了更大的提高。(2)分散的…载体表面温度更高：在与TMOS混合的各种有机硅烷中，链长大于丙基的烷基三甲氧基硅烷和多甲基甲氧基硅烷使固定化脂肪酶制剂的活性和热稳定性得到提高。当硅藻土，如市售的Celite 545作为载体材料时，固定化的脂肪酶具有最大的酯化活性。通过对各种制备条件的优化，包埋脂肪酶的热稳定性比沉积的脂肪酶提高了20~30ﾟC。这些结果和发现归因于：1)通过在杂化凝胶表面附近合理的紧密包埋，稳定了蛋白质球的三级结构；2)底物优先分配到疏水凝胶中；3)脂肪酶分子与有机硅胶中烷基之间的疏水相互作用。较少

Entrapment of lipase in organically modified silicates, which are derved from a mixture of tetramethoxysilane (TMOS) and alkyl group-containing organic silanes by the sol-gel method, leads to enhancement in esterification activity and thermal stability of immobilized preparation. In this study, we tried to form the lipase-entrapping gels either (1) in W/O microemulsion or (2) on the surface of support materials, and investigated some enzymatic properties of resultant immobilized lipase. In ester synthesis from butyric acid either isoamyl alcohol or ((]SY.+-。[))-menthol as a test reaction, the following results were obtained.(1) Microemulsion-based entrapment : Among various surfactants tested, the silicate-entrapped lipase prepared by using Brij 97 displayd a highest catalytic activity at room temperature. The organic-inorganic hybrid silicate derived from a mixture of TMOS and methyltrimethoxysilane resulted in a more enhanced activity of the immobilized lipase.(2) Dispersed entrapmen … More t on support surface : Among various organic silanes mixed with TMOS,alkyltrimethoxysilanes bearing longer chain length than propyl group, and methoxysilanes with multiple methyl groups brought about enhanced activity and thermostability of the immobilized lipase preparations. When kieselguhr such as commercially available Celite 545 was used as a support material, the entrapped lipase gave a mzximum esterification activity. There existed an optimum amount of gel and an optimum molar ratio of organic silane to TMOS.As the result of optimization of various preparation conditions, the thermostability of entrapped lipase was enhanced by 20-30ﾟC as compared with that of deposited counterpart.These results and findings might be ascribed to 1) stabilization of tertiary structure of protein globules by reasonably tight entrapment in close proximity of the hybrid gel surface, 2) preferential partitioning of substrates to the hydrophobic gel, and 3) hydrophobic interaction between lipase molecules and alkyl groups of the organic silica gel. Less