Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, United States.
Department of Chemistry, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, United States.
Anal Chem. 2020 May 5;92(9):6521-6528. doi: 10.1021/acs.analchem.0c00129. Epub 2020 Apr 23.
We describe the creation of a mass spectral library of acylcarnitines and conjugated acylcarnitines from the LC-MS/MS analysis of six NIST urine reference materials. To recognize acylcarnitines, we conducted in-depth analyses of fragmentation patterns of acylcarnitines and developed a set of rules, derived from spectra in the NIST17 Tandem MS Library and those identified in urine, using the newly developed hybrid search method. Acylcarnitine tandem spectra were annotated with fragments from carnitine and acyl moieties as well as neutral loss peaks from precursors. Consensus spectra were derived from spectra having similar retention time, fragmentation pattern, and the same precursor / and collision energy. The library contains 157 different precursor masses, 586 unique acylcarnitines, and 4 332 acylcarnitine consensus spectra. Furthermore, from spectra that partially satisfied the fragmentation rules of acylcarnitines, we identified 125 conjugated acylcarnitines represented by 987 consensus spectra, which appear to originate from Phase II biotransformation reactions. To our knowledge, this is the first report of conjugated acylcarnitines. The mass spectra provided by this work may be useful for clinical screening of acylcarnitines as well as for studying relationships among fragmentation patterns, collision energies, structures, and retention times of acylcarnitines. Further, these methods are extensible to other classes of metabolites.
我们描述了从 LC-MS/MS 分析 NIST 六种尿液参考物质中酰基肉碱和共轭酰基肉碱的质谱库的创建。为了识别酰基肉碱，我们对酰基肉碱的碎片模式进行了深入分析，并使用新开发的混合搜索方法，从 NIST17 串联 MS 库中的谱图以及在尿液中鉴定的谱图中得出了一套规则。酰基肉碱串联谱图用肉碱和酰基部分的片段以及来自前体的中性丢失峰进行注释。共识谱图源自具有相似保留时间、碎裂模式和相同前体/碰撞能的谱图。该库包含 157 种不同的前体质量、586 种独特的酰基肉碱和 4332 种酰基肉碱共识谱图。此外，从部分满足酰基肉碱碎裂规则的谱图中，我们鉴定了 125 种由 987 种共识谱图代表的共轭酰基肉碱，它们似乎源自 II 相生物转化反应。据我们所知，这是共轭酰基肉碱的首次报道。本工作提供的质谱可能有助于酰基肉碱的临床筛选，以及研究酰基肉碱的碎裂模式、碰撞能、结构和保留时间之间的关系。此外，这些方法可扩展到其他代谢物类别。
