STUDIES ON SULFATIDES BY QUADRUPOLE ION-TRAP MASS SPECTRMETRY WITH ELECTROSPRAY

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。用碰撞激活离解(CAD)四极离子陷阱串联电喷雾电离质谱法对硫脂的结构进行了表征。当在负离子模式下进行CAD时，硫脂的[M-H](-)离子产生丰富的结构信息离子，这些离子允许长链碱基和包括双键位置在内的脂肪酸组成的明确的辅助。脂肪酰基取代物上双键位置的确定是基于对经典电荷遥控碎裂过程中产生的一系列离子的观察，这些离子类似于高能CAD和串联四极杆质谱仪所观察到的离子。由于重排过程，也观察到不寻常的内部半乳糖残留物。硫脂的[M-H](-)离子也解离为神经酰胺阴离子，神经酰胺阴离子经历连续的碎裂过程，产生有助于鉴定神经酰胺部分的离子，并表明含有鞘氨醇亚类的硫脂与具有鞘氨醇长链碱基亚类的硫脂有区别。具有spingosine LCB和α-羟基脂肪酰基取代基(D18：1/HFA-硫脂)的硫酸酯亚类的MS(2)谱具有显著的离子组m/z568、550、540和522，它们来自脂肪酰基CO CH(OH)键的初级裂解，并且很容易与来自非羟基硫化物亚类(D18：1/NFA-硫脂)的那些离子组相区分，其中离子组丰度低。提出了硫脂在低能CAD作用下的碎裂途径。这些途径得到了各种化合物及其H-D交换类似物的MS和MS光谱的支持。

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. The structural characterization of sulfatides by collisional-activated dissoctiation (CAD) quadrupole ion-trap tandem mass spectrometric methods with electrospray ionization is described. When subjected to CAD in the negative-ion mode, the [M - H](-) ions of sulfatides yield abundant structurally informative ions that permit unequivocal assisgmensts of the long-chain base, and fatty acid constituent including the location of double bond. The identification of the position of the double bond on the fatty acyl substitute is based on the observation of the series of the ions arising from classical charge-remote fragmentation processes similar to those observied by high-energy CAD and by tandem quadrupole mass spectrometry. An unusual internal galactose residue due to a rearrangement process was also observed. The [M - H](-) ions of sulfatides also dissociates to a ceramide anion, which undergoes consecutive fragmentation porcesses to yield ions informative for identification of teh ceramide moiety and premits distinction the sulfatide with a sphingosine subclass from that with a sphinganine long-chain base subclass. The MS(2)-spectra of the sulfatide subclass with a spingosine LCB and a alpha-hydroxy fatty acyl substituent (d18:1/hFA-sulfatide) are featured by the prominent ion sets of m/z568, 550, 540 and 522, originated from a primary cleavage of the fatty acyl CO CH(OH) bond, and are readily differentiable from those arising from the non-hydroxy sulfatide subclass (d18:1/nFA-sulfatide), in which the ion sets are low abundance. The fragmentation pathways of sulfatides under low-energy CAD are proposed. The pathways are supported by the MS- and MS-spectra of various compounds, and of their H-D exchanged analogs.