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

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。我们报道了负离子电喷雾串联质谱法用于心脏磷脂（CL）结构表征的方法，这是一种含有两个不同磷脂酰基的四酰基链磷脂，其中连接到甘油骨架的脂肪酸残基的结构分配是通过低能CAD串联质谱法进行的，以前没有描述过。离子阱或串联四极杆仪器结合离子阱ms3谱或源CAD生成离子谱获得的[M - H]-和[M - 2H]2-离子的低能ms2谱为CL表征提供了完整的结构信息。[M - H]-离子的ms2光谱包含两组突出的片段离子，它们由磷脂酸、脱水磷脂酰甘油和（磷脂酸+ 136）阴离子组成。在[M - H]-离子的ms2光谱中观察到的两种不同的磷脂阴离子的丰度的显著差异导致了磷脂酰部分附着在中心甘油的1‘或3’位置上的分配。在进一步碰撞解离后，磷脂阴离子的ms3光谱提供了识别脂肪酰基取代基及其在甘油主链中的位置的信息。用TSQ或ITMS获得的[M - 2H]2-离子的ms2光谱包含互补信息，以确定结构归属。并论证了上述方法在心磷脂异构体鉴别和由多种分子结构组成的复杂心磷脂种类鉴定中的应用。

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.