Passarelli Melissa K, Ewing Andrew G, Winograd Nicholas
The Pennsylvania State University, Chemistry Building, University Park, PA 16802 ; The University of Gothenburg, Department of Chemistry, S-41296, Gothenburg, Sweden.
Surf Interface Anal. 2013 Jan 1;45(1):298-301. doi: 10.1002/sia.5036. Epub 2012 May 3.
Although secondary ion mass spectrometry (SIMS) has been successfully employed for mapping lipid distributions at the cellular level, the identification of intact lipid species in situ is often complicated by isobaric interference. The high mass resolution and tandem MS capabilities of a C(60)-QSTAR hybrid instrument has been utilized to identify over 50 lipid species from mouse macrophages (RAW 264.7). In this investigation, lipid assignments made based on mass accuracy were confirmed with tandem MS analyses. Data obtained from C(60)-SIMS was compared to LC-MS data obtained by the LIPID MAPS consortium. A majority of the lipids detected with LC-MS, but not detected with C(60)-SIMS were present at concentrations below 2.0 pmol/µg of DNA. Matrix related effects prevented the detection of lipids with the glycerophosphoethanolamine (PE) headgroup, glycerophosphoserine (PS) headgroup and lipids with polyunsaturated fatty acyl (PUFA) chains in the C(60)-SIMS analyses. Lipid distributions obtained from a lawn of RAW 264.7 cells stimulated with the endotoxin KDO(2)-Lipid A were also studied. The results obtained with C(60)-SIMS agreed with the established LC-MS data for the glycerophosphoinositol lipid class (PI) with adequate molecular sensitivity achieved with as few as 500 cells.
尽管二次离子质谱（SIMS）已成功用于在细胞水平绘制脂质分布图，但原位完整脂质种类的鉴定常常因等压干扰而变得复杂。C(60)-QSTAR 混合仪器的高质量分辨率和串联质谱功能已被用于从小鼠巨噬细胞（RAW 264.7）中鉴定出 50 多种脂质种类。在本研究中，基于质量准确度做出的脂质归属通过串联质谱分析得到了证实。将从 C(60)-SIMS 获得的数据与脂质代谢组学联盟获得的液相色谱-质谱（LC-MS）数据进行了比较。大多数用 LC-MS 检测到但未用 C(60)-SIMS 检测到的脂质，其浓度低于 2.0 pmol/μg DNA。在 C(60)-SIMS 分析中，基质相关效应阻碍了对带有甘油磷酰乙醇胺（PE）头部基团、甘油磷酰丝氨酸（PS）头部基团的脂质以及带有多不饱和脂肪酰基（PUFA）链的脂质的检测。还研究了用内毒素 KDO(2)-脂质 A 刺激的 RAW 264.7 细胞铺板的脂质分布。用 C(60)-SIMS 获得的结果与已确立的甘油磷酰肌醇脂质类别（PI）的 LC-MS 数据一致，用少至 500 个细胞就能实现足够的分子灵敏度。
