Li Fengling

Function of VP2 protein in the stability of the secondary structure of virus-like particles of genogroup II norovirus at different pH levels: function of VP2 protein in the stability of NoV VLPs.

VP2 is the minor structural protein of noroviruses (NoV) and may function in NoV particle stability. To determine the function of VP2 in the stability of the NoV particle, we constructed and purified two kinds of virus-like particles (VLPs), namely, VLPs (VP1) and VLPs (VP1+VP2), from Sf9 cells infected with recombinant baculoviruses by using a Bac-to-Bac® baculovirus expression system. The two kinds of VLPs were treated with different phosphate buffers (pH 2 to pH 8); the secondary structure was then analyzed by far UV circular dichroism (CD) spectroscopy. Results showed that significant disruptions of the secondary structure of proteins were not observed at pH 2 to pH 7. At pH 8, the percentages of a-helix, β-sheet, and β-turn in VLPs (VP1) were decreased from 11% to 8%, from 37% to 32%, and from 20% to 16%, respectively. The percentage of coil was increased from 32% to 44%. By contrast, the percentages of α-helix, β-sheet, and β-turn in VLPs (VP1+VP2) were decreased from 11% to 10%, from 37% to 35%, and from 20% to 19%, respectively. The percentage of coil was increased from 32% to 36%. VLPs (VP1+VP2) was likely more stable than VLPs (VP1), as indicated by the percentage of the secondary structures analyzed by CD. These results suggested that VP2 could stabilize the secondary structure of VLPs under alkaline pH conditions. This study provided novel insights into the molecular mechanism of the function of VP2 in the stability of NoV particles.

通过式固相萃取-液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查鱼肉中全氟化合物及其前体物质

采用通过式固相萃取技术去除样品基质中脂肪和磷脂等杂质干扰，利用液相色谱-四极杆/静电场轨道阱高分辨质谱（LC-Q Exactive Orbitrap MS）的同时定性定量功能，建立了鱼肉中18种全氟化合物（Perfluorinated compounds，PFCs）及其21种前体物质的同时分析方法。样品经90%乙腈溶液提取，Oasis PRiME HLB通过式固相萃取柱净化，C 18 色谱柱分离，同时在液相色谱系统混合器和进样器之间串联一根延迟色谱柱，去除液相色谱系统的背景干扰； 质谱数据采集使用Q Exactive高分辨质谱的Full MS/dd-MS 2 监测模式，以Full MS一级质谱全扫描提取母离子精确质量数所得的色谱峰面积进行定量，以保留时间和dd-MS 2 数据依赖子离子扫描所得的二级子离子质谱图进行定性确证。39种目标物的精确质量数偏差不大于3×10 -6 ，浓度与母离子峰面积的线性关系良好，相关系数≥0.99，检出限为0.02~0.50 μg/kg。基质加标回收率在61.7%~122%之间，相对标准偏差（RSD）为6.9%~18.8%。 本方法实现了18种PFCs及其21种前体物质的同时确证和测定，拓展了生物基质中全氟化合物的检测种类，而且前处理方法更为简化、部分化合物的灵敏度比文献报道方法提高约一个数量级，为全氟化合物前体物质的生物转化研究提供了高效的技术基础。