School of Chemistry, Biology, and Material Engineering, Suzhou University of Science and Technology, Suzhou, 215009, P. R. China.
Emory University, MSC 5919, 810 Whatcoat St, Oxford, GA, USA.
Appl Biochem Biotechnol. 2020 Mar;190(3):826-838. doi: 10.1007/s12010-019-03131-w. Epub 2019 Sep 7.
β-Glucosidase (BG) hydrolyzes cellobiose into glucose, and is a vital step in converting ionic liquids (ILs)-pretreated biomass to sustainable biofuels. The inactivation mechanism of BG from Paenibacillus sp. LLZ1 induced by microcrystalline cellulose was explored in various concentrations of ILs, composed of [Emim] cation and [DEP], [OAc], [Br], [Cl], and [BF] anions. The FTIR analysis of inactivated BG indicated that the ILs altered its β-sheet content. Moreover, circular dichroism spectroscopy (CD) suggested that the α-helix content decreased, while the β-sheet content increased with the presence of ILs in general. Interestingly, the secondary structure of BG had almost no change after [Emim]DEP treatment, while ionic liquid [Emim]BF treatment caused the irreversible denaturation of BG. Eventually, by adding 0.4 mM of Aerosol OT surfactant, the BG activity was increased by 20.1% in the presence of 25% [Emim]DEP, and the corresponding glucose yield from hydrolysis of cellobiose was increased by 23.9%.
β-葡萄糖苷酶（BG）将纤维二糖水解成葡萄糖，是将离子液体（ILs）预处理的生物质转化为可持续生物燃料的关键步骤。本研究探索了嗜热脂肪地芽孢杆菌 LLZ1 来源的 BG 在不同浓度 ILs（[Emim]阳离子和[DEP]、[OAc]、[Br]、[Cl]和[BF]阴离子）中的微晶纤维素诱导失活动力学。失活 BG 的傅里叶变换红外光谱（FTIR）分析表明，ILs 改变了其β-折叠含量。此外，圆二色性光谱（CD）表明，一般来说，α-螺旋含量随着 ILs 的存在而降低，而β-折叠含量增加。有趣的是，[Emim]DEP 处理后 BG 的二级结构几乎没有变化，而离子液体[Emim]BF 处理导致 BG 不可逆变性。最终，通过添加 0.4mM 的 Aerosol OT 表面活性剂，在 25%[Emim]DEP 存在下 BG 活性提高了 20.1%，并且从纤维二糖水解获得的相应葡萄糖产量提高了 23.9%。
