Ozone-induced dissociation: Elucidation of double bond position within mass-selected lipid ions
Ozone-induced dissociation: Elucidation of double bond position within mass-selected lipid ions
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DOI：
10.1021/ac7017684
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发表时间：
2008-01-01
影响因子：
7.4
通讯作者：
Blanksby, Stephen J.
中科院分区：
文献类型：
--
作者：
Thomas, Michael C.;Mitchell, Todd W.;Blanksby, Stephen J.
在粗脂提取物电喷雾电离过程中，由脂质形成的离子在四极线性离子阱质谱仪中被大量选择，并允许与臭氧蒸汽反应。不饱和脂离子与臭氧之间的气相离子-分子反应发现分子内每个碳-碳双键产生两个主要产物离子。这些化学诱导碎片的质量电荷比是前体离子中不饱和位置的诊断。这种新的分析技术被称为臭氧诱导离解（OzID），可以与传统的碰撞诱导离解（CID）串联或并行应用，在复杂混合物中提供未知脂类的近乎完整的结构分配，而无需事先分馏或衍生化。在这项研究中，OzID被应用于一系列复杂的脂质提取物，包括人晶状体、牛肾和商业橄榄油，从而证明该技术适用于广泛的脂质类别，包括中性和酸性甘油磷脂、鞘磷脂和三酰基甘油。气相臭氧分解反应还观察到不同类型的前体离子，包括[M + H](+), [M + Li](+), [M + Na]（+）和[M H](-)：在每种情况下产生的碎片数据允许双键位置的明确分配。在人晶体脂质提取物中，使用CID和OzID组合鉴定了三个鞘磷脂区域异构体，即SM(d18:0/15Z-24:1)， SM（d18:0/17Z-24:1）和SM(d18:0/19Z-24:1)，以及一种新型磷脂酰乙醇胺烷基醚GPEtn（11Z-18:1e/9Z18:1）。这些发现表明，仅基于CID的脂质鉴定掩盖了脂质生物化学的自然结构多样性，并说明了OzID作为自动化、高通量脂质分析方案的补充方法的潜力。
Ions formed from lipids during electrospray ionization of crude lipid extracts have been mass-selected within a quadrupole linear ion trap mass spectrometer and allowed to react with ozone vapor. Gas-phase ion-molecule reactions between unsaturated lipid ions and ozone are found to yield two primary product ions for each carbon-carbon double bond within the molecule. The mass-to-charge ratios of these chemically induced fragments are diagnostic of the position of unsaturation within the precursor ion. This novel analytical technique, dubbed ozone-induced dissociation (OzID), can be applied both in series and in parallel with conventional collision-induced dissociation (CID) to provide near-complete structural assignment of unknown lipids within complex mixtures without prior fractionation or derivatization. In this study, OzID is applied to a suite of complex lipid extracts from sources including human lens, bovine kidney, and commercial olive oil, thus demonstrating the technique to be applicable to a broad range of lipid classes including both neutral and acidic glycerophospholipids, sphingomyelins, and triacylglycerols. Gas-phase ozonolysis reactions are also observed with different types of precursor ions including [M + H](+), [M + Li](+), [M + Na](+), and [M H](-): in each case yielding fragmentation data that allow double bond position to be unambiguously assigned. Within the human lens lipid extract, three sphingomyelin regioisomers, namely SM(d18:0/15Z-24:1), SM(d18:0/17Z-24:1), and SM(d18:0/19Z-24:1), and a novel phosphatidylethanolamine alkyl ether, GPEtn(11Z-18:1e/9Z18:1), are identified using a combination of CID and OzID. These discoveries demonstrate that lipid identification based on CID alone belies the natural structural diversity in lipid biochemistry and illustrate the potential of OzID as a complementary approach within automated, high-throughput lipid analysis protocols.