Lewis Sigler Institute for Integrative Genomics and Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Anal Chem. 2020 Sep 1;92(17):11573-11581. doi: 10.1021/acs.analchem.0c00985. Epub 2020 Aug 12.
Annotation of untargeted high-resolution full-scan LC-MS metabolomics data remains challenging due to individual metabolites generating multiple LC-MS peaks arising from isotopes, adducts, and fragments. Adduct annotation is a particular challenge, as the same mass difference between peaks can arise from adduct formation, fragmentation, or different biological species. To address this, here we describe a buffer modification workflow (BMW) in which the same sample is run by LC-MS in both liquid chromatography solvent with NH-acetate buffer and in solvent with the buffer modified with NH-formate. Buffer switching results in characteristic mass and signal intensity changes for adduct peaks, facilitating their annotation. This relatively simple and convenient chromatography modification annotated yeast metabolomics data with similar effectiveness to growing the yeast in isotope-labeled media. Application to mouse liver data annotated both known metabolite and known adduct peaks with 95% accuracy. Overall, it identified 26% of ∼27 000 liver LC-MS features as putative metabolites, of which ∼2600 showed HMDB or KEGG database formula match. This workflow is well suited to biological samples that cannot be readily isotope labeled, including plants, mammalian tissues, and tumors.
由于同位素、加合物和碎片的存在，非靶向高分辨率全扫描 LC-MS 代谢组学数据的注释仍然具有挑战性。加合物注释是一个特别的挑战，因为峰之间的相同质量差异可能是由于加合物形成、碎片化或不同的生物种类引起的。为了解决这个问题，我们在这里描述了一种缓冲液修饰工作流程 (BMW)，其中相同的样品通过 LC-MS 在含有 NH-乙酸盐缓冲液的液相色谱溶剂和含有缓冲液修饰的 NH-甲酸盐的溶剂中运行。缓冲液切换导致加合物峰的特征质量和信号强度发生变化，从而便于对其进行注释。这种相对简单方便的色谱修饰方法对酵母代谢组学数据的注释效果与在同位素标记培养基中培养酵母相似。应用于小鼠肝脏数据，以 95%的准确度注释了已知代谢物和已知加合物峰。总的来说，它将约 27000 个肝脏 LC-MS 特征中的 26%鉴定为假定代谢物，其中约 2600 个显示出 HMDB 或 KEGG 数据库公式匹配。该工作流程非常适合不易进行同位素标记的生物样本，包括植物、哺乳动物组织和肿瘤。
