Du Yang, Zhao Fengjiao, Xing Junpeng, Liu Zhiqiang, Cui Meng
Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin130022, China.
University of Science and Technology of China, Hefei, Anhui230029, China.
J Am Soc Mass Spectrom. 2023 Mar 1;34(3):366-373. doi: 10.1021/jasms.2c00238. Epub 2023 Feb 3.
Flavonoids are polyphenolic secondary metabolites with extensive biological activities and pharmacological effects. Exploring the interactions of flavonoids with proteins may be helpful for understanding their biological processes. Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool to characterize the noncovalent protein-ligand (PL) complexes. However, some protein-flavonoid complexes are labile during electrospray ionization. Here, the labile lysozyme-flavonoid (rutin, icariin, and naringin) complexes were determined by direct ESI-MS without derivation. It has been found that low amounts of N-methylpyrrolidinone and dimethylformamide can protect labile lysozyme-flavonoid complexes away from dissociation during electrospray ionization process. The intact lysozyme-flavonoid complexes were specifically observed in mass spectra, and the measured binding affinities by ESI-MS were matched with the fluorescence data. The effects of additives on the analysis of lysozyme-flavonoid complexes were investigated by ESI-MS, combined with the molecular docking and fluorescence. This strategy was helpful to investigate the labile PL interactions by direct ESI-MS.
黄酮类化合物是具有广泛生物活性和药理作用的多酚类次生代谢产物。探索黄酮类化合物与蛋白质的相互作用可能有助于理解它们的生物学过程。电喷雾电离质谱（ESI-MS）是表征非共价蛋白质-配体（PL）复合物的有力工具。然而，一些蛋白质-黄酮类化合物复合物在电喷雾电离过程中不稳定。在此，通过直接ESI-MS无需衍生化即可测定不稳定的溶菌酶-黄酮类化合物（芦丁、淫羊藿苷和柚皮苷）复合物。已发现少量的N-甲基吡咯烷酮和二甲基甲酰胺可保护不稳定的溶菌酶-黄酮类化合物复合物在电喷雾电离过程中不发生解离。在质谱中特异性观察到完整的溶菌酶-黄酮类化合物复合物，通过ESI-MS测定的结合亲和力与荧光数据相符。结合分子对接和荧光，通过ESI-MS研究了添加剂对溶菌酶-黄酮类化合物复合物分析的影响。该策略有助于通过直接ESI-MS研究不稳定的PL相互作用。
