Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States.
J Am Chem Soc. 2021 Apr 7;143(13):5172-5181. doi: 10.1021/jacs.1c01352. Epub 2021 Mar 24.
Molecular imprinting is a powerful and yet simple method to create multifunctional binding sites within a cross-linked polymer network. We report a new class of synthetic glucosidase prepared through molecular imprinting and postfunctionalization of cross-linked surfactant micelles. These catalysts are protein-sized water-soluble nanoparticles that can be modified in multiple ways. As their natural counterparts, they bind a glucose-containing oligo- or polysaccharide. They contain acidic groups near the glycosidic bond to be cleaved, with the number and distance of the acid groups tuned systematically. Hydrolysis of cellulose in a key step in biomass conversion but is hampered by the incalcitrance of the highly crystalline cellulose fibers. The synthetic glucosidases are shown to hydrolyze cellobiose and cellulose under a variety of conditions. The best catalyst, with a biomimetic double acid catalytic motif, can hydrolyze cellulose with one-fifth of the activity of commercial cellulases in aqueous buffer. As a highly cross-linked polymeric nanoparticle, the synthetic catalyst is stable at elevated temperatures in both aqueous and nonaqueous solvents. In a polar aprotic solvent/ionic liquid mixture, it hydrolyzes cellulose several times faster than commercial cellulases in aqueous buffer. When deposited on magnetic nanoparticles, it retains 75% of its activity after 10 cycles of usage.
分子印迹是一种强大而简单的方法，可以在交联聚合物网络中创建多功能结合位点。我们报告了一种通过分子印迹和交联表面活性剂胶束的后功能化制备的新型合成葡萄糖苷酶。这些催化剂是蛋白大小的水溶性纳米颗粒，可以通过多种方式进行修饰。与天然对应物一样，它们结合含有葡萄糖的寡糖或多糖。在要切割的糖苷键附近存在酸性基团，并且酸性基团的数量和距离被系统地调整。纤维素的水解是生物质转化中的关键步骤，但由于高度结晶的纤维素纤维的顽固性而受到阻碍。合成的葡萄糖苷酶在多种条件下显示出对纤维二糖和纤维素的水解作用。具有仿生双酸催化基序的最佳催化剂可以在水缓冲液中以商业纤维素酶五分之一的活性水解纤维素。作为一种高度交联的聚合物纳米颗粒，合成催化剂在水相和非水溶剂中在高温下都稳定。在极性非质子溶剂/离子液体混合物中，它在纤维素缓冲液中的水解速度比商业纤维素酶快几倍。当沉积在磁性纳米颗粒上时，它在 10 次使用循环后保留了 75%的活性。
