Department of Chemistry, University of Texas, Austin, Texas 78712, United States.
Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, United States.
Anal Chem. 2024 Jun 4;96(22):9151-9158. doi: 10.1021/acs.analchem.4c00952. Epub 2024 May 17.
Lipopolysaccharides (LPS) and lipooligosaccharides (LOS) are located in the outer membrane of Gram-negative bacteria and are comprised of three distinctive parts: lipid A, core oligosaccharide (OS), and O-antigen. The structure of each region influences bacterial stability, toxicity, and pathogenesis. Here, we highlight the use of targeted activated-electron photodetachment (a-EPD) tandem mass spectrometry to characterize LPS and LOS from two crucial players in the human gut microbiota, Nissle and . a-EPD is a hybrid activation method that uses ultraviolet photoirradiation to generate charge-reduced radical ions followed by collisional activation to produce informative fragmentation patterns. We benchmark the a-EPD method for top-down characterization of triacyl LOS from R2, then focus on characterization of LPS from Nissle and . Notably, a-EPD affords extensive fragmentation throughout the backbone of the core OS and O-antigen regions of LPS from Nissle. This hybrid approach facilitated the elucidation of structural details for LPS from , revealing a putative hexuronic acid (HexA) conjugated to lipid A.
脂多糖 (LPS) 和脂寡糖 (LOS) 位于革兰氏阴性菌的外膜中,由三个不同的部分组成:脂质 A、核心寡糖 (OS) 和 O-抗原。每个区域的结构都影响细菌的稳定性、毒性和发病机制。在这里,我们重点介绍了靶向活性电子光离解 (a-EPD) 串联质谱法在鉴定人类肠道微生物群中两个关键成员 Nissle 和 中的 LPS 和 LOS 中的应用。a-EPD 是一种混合激活方法,它使用紫外光照射产生电荷还原的自由基离子,然后进行碰撞激活以产生信息丰富的碎片模式。我们对 R2 中的三酰基 LOS 进行了自上而下的 a-EPD 特征分析,并对 Nissle 和 中的 LPS 进行了特征分析。值得注意的是,a-EPD 可以对 Nissle 中 LPS 的核心 OS 和 O-抗原区域的整个骨架进行广泛的碎片化。这种混合方法促进了 Nissle 中 LPS 的结构细节的阐明,揭示了与脂质 A 相连的可能的六元羧酸 (HexA)。