The analysis of 13C-labeled lipids by mass spectrometry is challenging due to the complexity from labeling the large number of carbon atoms in lipids. To further add to the complexity, different adducts can be produced during electrospray ionization and in-source fragmentation, which can create complex overlapping isotope patterns that can only be resolved using high-resolution mass spectrometry. Co-elution of lipids even after chromatographic separation also adds to the potential for overlapping mass spectra. Here, we describe a procedure that enables full 13C-labeled patterns to be resolved in complex microalgal lipid extracts as well a procedure that provides structural labeling information. Mass resolving powers of 240000 full width half-maximum (fwhm) and fast targeted MS/MS allowed the differentiation of isotopologues, adducts, and unresolved lipid species after chromatographic separation. This enabled the percentage of 13C enrichment to be calculated for each individual lipid species over a time series in the microalgal lipidome. The application of tandem mass spectrometry (MS/MS) also allowed the degree of labeling within the headgroup vs acyl chains to be determined, further adding to the detail of information collected. This information is particularly useful for studying lipid synthesis and remodeling processes and can be extended to other biological systems.

中文翻译：

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用于解析微藻脂质体中 13C 富集模式的超高分辨率质谱方法。


由于标记脂质中大量碳原子的复杂性，通过质谱分析 13C 标记的脂质具有挑战性。为了进一步增加复杂性，在电喷雾电离和源内碎裂过程中可能会产生不同的加合物，这可能会产生复杂的重叠同位素模式，而这些模式只能使用高分辨率质谱法来解析。即使在色谱分离后，脂质的共洗脱也增加了重叠质谱的可能性。在这里，我们描述了一种能够在复杂的微藻脂质提取物中解析完整 13C 标记模式的程序，以及提供结构标记信息的程序。 240000 半峰全宽 (fwhm) 的质量分辨能力和快速靶向 MS/MS 允许在色谱分离后区分同位素体、加合物和未解析的脂质种类。这使得能够计算微藻脂质组中每个脂质种类在一段时间内的 13C 富集百分比。串联质谱 (MS/MS) 的应用还可以确定头基与酰基链内的标记程度，进一步增加收集信息的细节。该信息对于研究脂质合成和重塑过程特别有用，并且可以扩展到其他生物系统。