Department of Chemistry, School of Sciences, Zhejiang Sci-Tech University, 5 Second Avenue, Xiasha Higher Education Zone, Hangzhou, China.
Enzyme Microb Technol. 2013 Jul 10;53(2):79-84. doi: 10.1016/j.enzmictec.2013.04.011. Epub 2013 May 13.
A general strategy was demonstrated here to immobilize proteins with various isoelectric points (IPs) in layered titanates. The immobilization of proteins with relative low IPs, such as bovine serum albumin (BSA) and lipase, in layered titanates was successfully by a novel polyelectrolyte-assisted electrostatic self-assembly technique, which is impossible by a conventional electrostatic self-assembly method. Lysozyme with relative high IP was detractively interacted with negative titanate nanosheets to form a bioinorganic composite. The native structures of proteins were retained after immobilizing although a significant difference in microstructures was observed among these composites. The amounts of immobilized proteins were up to ~68.3 wt.% for lysozyme, 37.2 wt.% for BSA and 21.5 wt.% for lipase. These composites were stable in the neutral and weakly acidic condition, and only releases <10% proteins in the pH<4 solution. The immobilized lysozyme and lipase exhibit excellent thermal stability, which retain their initial activities of about 70% at 70 °C for about 40 min. In addition, these composites are reusable, and the residual activities of immobilized enzymes are 68% for lysozyme and 61% for lipase after 10 recycles.
这里展示了一种将具有不同等电点（IP）的蛋白质固定在层状钛酸盐中的通用策略。通过一种新的聚电解质辅助静电自组装技术，可以成功地将相对低等电点的蛋白质（如牛血清白蛋白（BSA）和脂肪酶）固定在层状钛酸盐中，而传统的静电自组装方法是不可能的。具有相对高等电点的溶菌酶与负的钛酸盐纳米片之间存在排斥作用，形成了一种生物无机复合材料。尽管这些复合材料的微观结构存在显著差异，但固定蛋白质后仍保留了其天然结构。固定的蛋白质的量高达~68.3wt.%的溶菌酶，37.2wt.%的BSA 和 21.5wt.%的脂肪酶。这些复合材料在中性和弱酸性条件下稳定，仅在 pH<4 的溶液中释放<10%的蛋白质。固定的溶菌酶和脂肪酶表现出优异的热稳定性，在 70°C 下约 40 分钟内保留了其初始活性的约 70%。此外，这些复合材料可重复使用，经过 10 次循环后，固定酶的残余活性分别为溶菌酶的 68%和脂肪酶的 61%。
