Gas phase derivatization for lipidomic MS analysis

描述（由申请人提供）：脂质组学方法现在获得认可是基于快速，全面的质谱（MS）分析碳长度和脂肪酰基的不饱和程度及其在甘油脂的第1,2或3位的位置（区域特异性）。脂质组学分析面临的最重要的分析问题是，目前还没有一种通用的方法能够同时提供脂肪酰基的双键位置和区域特异性信息。我们建议利用我们实验室开发的一种新的质谱方法，该方法应该能够完整、自动地表征粗脂提取物中所有酰基化的脂质。在化学电离（Cl）质谱（MS）过程中产生加合物的离子-分子反应实际上是一个气相衍生化过程。在1999年以来的8篇系列论文中，我们报道了用乙腈CI/MS/MS共同发现了不饱和脂肪酸甲酯（FAME）的气相衍生化反应。所得加合物的破碎提供了第一个快速、方便的FAME结构分析。乙腈CI在m/ z54处产生一个离子，在双键间共价加成；由此产生的[M+54]+离子在碰撞激活后经历电荷驱动的碎裂，产生诊断离子，明确地确定了多不饱和化合物中双键的位置。最近，这一反应已被观察到大气压CI在液体流。我们提出了一个双管齐下的方法：1)开发基于乙腈的APCI，用于分析来自粗脂提取物的脂类中脂肪酰基的双键位置；2)完成乙腈GClCIIMSlMS的开发，包括分析所有多不饱和非亚甲基中断脂肪酸。这些目标最终将与传统的MS/MS模式（前体，产物和中性损失扫描）相结合，气相衍生化含酰基化合物的分析应该为大多数甘油脂提供完整的结构和定量信息，并且可以自动进行脂质组学分析。

DESCRIPTION (provided by applicant): Lipidomic approaches now gaining acceptance are based on the rapid, comprehensive mass spectrometry (MS) analysis of carbon length and degree of unsaturation in fatty acyl groups and their positions (regiospecificity) at the sn 1,2, or 3 positions of glycerolipids. The most important analytical issue facing lipidomic analysis is that no general method has emerged that delivers double bond position in the fatty acyl groups simultaneously with regiospecific information, We propose to exploit a novel mass spectrometric method developed in our laboratory that should enable complete, automated characterization of all acylated lipids in crude lipid extracts, Ion-molecule reactions that result in adducts during chemical ionization (Cl) mass spectrometry (MS) are effectively a gas phase derivatization process. In a series of 8 papers since 1999, we reported co-discovery of gas derivatization of unsaturated fatty acid methyl esters (FAME) by acetonitrile CI/MS/MS. Fragmentation of the resulting adducts provides the first rapid, convenient structural analysis of FAME. Acetonitrile CI produces an ion at m/z 54 which adds covalently across double bonds; the resulting [M+54]+ ion undergoes charge-driven fragmentation upon collisional activation to yield diagnostic ions that unequivocally establish the position of double bonds in polyunsaturates. Recently, this reaction has been observed for atmospheric pressure CI in a liquid stream. We propose a two pronged approach where we 1) develop APCI based on acetonitrile for analysis of double bond position for fatty acyl groups within lipid classes derived from crude lipid extracts, and 2) complete development of acetonitrile GClCIIMSlMS to include analysis of all polyunsaturated non-methylene-interrupted fatty acids. These goals will eventually be coupled, and together with conventional MS/MS modes (precursor, product, and neutral loss scans), analysis of gas phase derivatized acyl-containing compounds should provide complete structural and quantitative information for most glycerolipids and can be automated for lipidomic analysis.