MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
Analyst. 2020 Jan 20;145(2):513-522. doi: 10.1039/c9an01515a.
Plasmanyl and plasmenyl glycerophosphocholine are ether lipids featuring the 1-O-alkyl or 1-O-alk-1'-enyl ether linkage at the sn-1 position of the glycerol backbone, respectively. Aberrant levels of ether glycerophosphocholines (ether PCs) have been correlated with cellular dysfunctions and various human diseases. Profiling ether PCs with accurate structural information is challenging because of the common presence of isomeric and isobaric species in a lipidome. The Paternò-Büchi (PB) reaction, a double bond (C[double bond, length as m-dash]C) specific derivatization method, is capable of pinpointing C[double bond, length as m-dash]C locations in unsaturated lipids, when coupled with subsequent tandem mass spectrometry (MS/MS). In this study, we have tailored the acetone PB reaction for the analysis of ether PCs. PB-MS/MS via low energy collision-induced dissociation (CID) provides diagnostic ions specific to the alkenyl ether C[double bond, length as m-dash]C bond, which are different from those derived from the isolated C[double bond, length as m-dash]C bond in the alkyl or acyl chain, thereby facilitating the distinction of isomeric plasmenyl from plasmanyl PCs. PB-MS/MS coupled with high resolution MS and multi-stage MS/MS further enable confident identification of isomeric ether PCs and isobaric diacyl PCs from mixtures. A total of 45 ether PCs in human plasma have been identified for ether linkage type and chain composition, while 28 ether PCs have structures being fully characterized down to C[double bond, length as m-dash]C locations.
Plasmanyl 和 plasmenyl 甘油磷胆碱分别是甘油骨架 sn-1 位上具有 1-O-烷基或 1-O-烯基醚键的醚脂类。异常水平的醚甘油磷胆碱（醚 PC）与细胞功能障碍和各种人类疾病有关。由于脂质组中存在异构和等质量的物种，因此具有准确结构信息的醚 PC 谱图分析具有挑战性。Paternò-Büchi（PB）反应是一种双键（C[双键，长度为破折号]C）特异性衍生化方法，当与随后的串联质谱（MS/MS）结合使用时，能够精确定位不饱和脂质中的 C[双键，长度为破折号]C 位置。在这项研究中，我们对用于分析醚 PC 的丙酮 PB 反应进行了调整。通过低能量碰撞诱导解离（CID）的 PB-MS/MS 提供了特定于烯基醚 C[双键，长度为破折号]C 键的诊断离子，这些离子与烷基或酰基链中孤立的 C[双键，长度为破折号]C 键衍生的离子不同，从而有助于区分异构的 plasmenyl 和 plasmanyl PCs。PB-MS/MS 与高分辨率 MS 和多级 MS/MS 相结合，进一步能够从混合物中可靠地鉴定出异构醚 PC 和等质量的二酰基 PC。共鉴定出 45 种人血浆中的醚 PC ，确定了醚键类型和链组成，而 28 种醚 PC 的结构完全表征到 C[双键，长度为破折号]C 位置。
