CHAR OF CARDIOLIPIN BY TQ & MSQ ION-TRAP MASS SPEC WITH ELECTROSPRAY IONIZ

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。我们报告了用于心磷脂（CL）结构表征的负离子电喷雾串联质谱方法，心磷脂（CL）是一种含有两个不同磷脂酰部分的四酰基链磷脂，其中通过低能量CAD串联质谱法对附着在甘油骨架上的脂肪酸残基进行了结构归属之前尚未描述过。用离子阱或串联四极杆仪器获得的[M-H]-和[M -2 H]2-离子的低能MS 2-谱与离子阱MS 3-谱或源CAD产物离子谱相结合，为CL表征提供了完整的结构信息。[M-H]-离子的MS 2-光谱包含两组主要碎片离子，包括磷脂酸、脱水磷脂酰甘油和（磷脂酸+136）阴离子。在[M-H]-离子的MS 2-光谱中观察到的两种不同磷脂阴离子丰度的显著差异导致连接到中心甘油的1'或3'位置的磷脂酰部分的归属。在进一步碰撞解离后，磷脂阴离子的MS 3-光谱提供了识别脂肪酰基取代基及其在甘油骨架中的位置的信息。采用TSQ或ITMS获得的[M -2 H]2-离子的MS 2-光谱包含确认结构归属的补充信息。上述方法在心磷脂异构体的分化和复杂的心磷脂物种组成的多个分子结构的鉴定中的应用也得到了证明。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We report negative-ion electrospray tandem mass spectrometric methods for structural characterization of cardiolipin (CL), a four-acyl-chain phospholipid containing two distinct phosphatidyl moieties, of which structural assignment of the fatty acid residues attached to the glycerol backbones performed by low-energy CAD tandem mass spectrometry has not been previously described. The low-energy MS2-spectra of the [M - H]- and [M - 2H]2- ions obtained with ion-trap or with tandem quadrupole instrument combined with ion-trap MS3-spectra or with source CAD product-ion spectra provide complete structural information for CL characterization. The MS2-spectra of the [M - H]- ions contain two sets of prominent fragment ions that comprise a phosphatidic acid, a dehydrated phosphatidylglycerol, and a (phosphatidic acid + 136) anion. The substantial differences in the abundances of the two distinct phosphatidic anions observed in the MS2-spectra of the [M - H]- ions lead to the assignment of the phosphatidyl moieties attached to the 1' or 3' position of central glycerol. Upon further collisional dissociation, the MS3-spectra of the phosphatidic anions provide information to identify the fatty acyl substituents and their position in the glycerol backbone. The MS2-spectra of the [M - 2H]2- ions obtained with TSQ or ITMS contain complementary information to confirm structural assignment. The applications of the above methods in the differentiation of cardiolipin isomers and in the identification of complex cardiolipin species consisting of multiple molecular structures are also demonstrated.