Jia Hongfei, Zhu Guangyu, Vugrinovich Bradley, Kataphinan Woraphon, Reneker Darrell H, Wang Ping
Department of Chemical Engineering, The University of Akron, Akron, Ohio 44325-3906, USA.
Biotechnol Prog. 2002 Sep-Oct;18(5):1027-32. doi: 10.1021/bp020042m.
Improvement of catalytic efficiency of immobilized enzymes via materials engineering was demonstrated through the preparation of bioactive nanofibers. Bioactive polystyrene (PS) nanofibers with a typical diameter of 120 nm were prepared and examined for catalytic efficiency for biotransformations. The nanofibers were produced by electrospinning functionalized PS, followed by the chemical attachment of a model enzyme, alpha-chymotrypsin. The observed enzyme loading as determined by active site titration was up to 1.4% (wt/wt), corresponding to over 27.4% monolayer coverage of the external surface of nanofibers. The apparent hydrolytic activity of the nanofibrous enzyme in aqueous solutions was over 65% of that of the native enzyme, indicating a high catalytic efficiency as compared to other forms of immobilized enzymes. Furthermore, nanofibrous alpha-chymotrypsin exhibited a much-improved nonaqueous activity that was over 3 orders of magnitude higher than that of its native counterpart suspended in organic solvents including hexane and isooctane. It appeared that the covalent binding also improved the enzyme's stability against structural denaturation, such that the half-life of the nanofibrous enzyme in methanol was 18-fold longer than that of the native enzyme.
通过制备生物活性纳米纤维，证明了通过材料工程提高固定化酶的催化效率。制备了典型直径为120nm的生物活性聚苯乙烯（PS）纳米纤维，并检测其生物转化的催化效率。纳米纤维通过静电纺丝功能化PS制备，随后化学连接模型酶α-胰凝乳蛋白酶。通过活性位点滴定法测定的观察到的酶负载量高达1.4%（重量/重量），对应于纳米纤维外表面超过27.4%的单层覆盖。纳米纤维酶在水溶液中的表观水解活性超过天然酶的65%，表明与其他形式的固定化酶相比具有较高的催化效率。此外，纳米纤维α-胰凝乳蛋白酶表现出大大提高的非水活性，比悬浮在包括己烷和异辛烷在内的有机溶剂中的天然对应物高出3个数量级以上。共价结合似乎也提高了酶对结构变性的稳定性，使得纳米纤维酶在甲醇中的半衰期比天然酶长18倍。
