Biomacromolecules. 2018 Jun 11;19(6):2286-2293. doi: 10.1021/acs.biomac.8b00258. Epub 2018 May 9.
β-Glucosidase (BG) catalyzes the hydrolysis of cellobiose to glucose and is a rate-limiting enzyme in the conversion of lignocellulosic biomass to sugars toward biofuels. Since the cost of enzyme is a major contributor to biofuel economics, we report the bioconjugation of a temperature-responsive polymer with the highly active thermophilic β-glucosidase (B8CYA8) from Halothermothrix orenii toward improving enzyme recyclability. The bioconjugate, with a lower critical solution temperature (LCST) of 33 °C withstands high temperatures up to 70 °C. Though the secondary structure of the enzyme in the conjugate is slightly distorted with a higher percentage of β-sheet like structure, the stability and specific activity of B8CYA8 in the conjugate remains unaltered up to 30 °C and retains more than 70% specific activity of the unmodified enzyme at 70 °C. The conjugate can be reused for β-glucosidic bond cleavage of cellobiose for at least four cycles without any significant loss in specific activity.
β-葡萄糖苷酶（BG）催化纤维二糖水解为葡萄糖，是木质纤维素生物质转化为糖以生产生物燃料过程中的限速酶。由于酶的成本是生物燃料经济的主要贡献因素，我们报告了一种温度响应性聚合物与高温嗜热β-葡萄糖苷酶（B8CYA8）的生物偶联，以提高酶的可回收性。该生物偶联物的低临界溶液温度（LCST）为 33°C，可承受高达 70°C 的高温。尽管偶联物中酶的二级结构略有扭曲，具有更高比例的β-折叠样结构，但 B8CYA8 在偶联物中的稳定性和比活性在 30°C 下保持不变，在 70°C 下仍保留未修饰酶的 70%以上的比活性。该偶联物可用于纤维二糖的β-糖苷键断裂，至少可重复使用 4 次，而比活性没有明显损失。
