STRUCTURAL CHARACTERIZATION OF PHOSPHATIDYL-MYO-INOSITOL MANNOSIDES FROM

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 介绍了单酰化PIM(三酰化PIM)和二酰化PIM(四酰化PIM)的多级离子陷阱质谱学方法，即分别由一个或两个附加的脂肪酸取代基所组成的二酰化PIM(二酰化PIM)。虽然甘油主链上的脂肪酸取代基的指认和确认可以通过前一篇文章中描述的方法很容易地实现，但是通过观察单酰基-PIM和双酰基-PIM的MS2谱中二酰甘油部分([M-H-二甘油]-)裂解产生的显著的酰基糖苷离子，可以确定糖苷部分及其酰化状态的同一性。2-O-甘露糖苷(即R3CO2H)和肌醇(即R4CO2H)上的脂肪酸取代基的区别是基于以下发现：[M-H-二酰基甘油]-的MS3光谱中包含一个由于2-O-甘露糖苷上的脂肪酸进一步丢失而产生的显著离子(即[M-H-二甘油-R3CO2H]-离子)；而由于肌醇上的脂肪酸取代基(即[M-H-二甘油-R4CO2H]-离子)的丢失而产生的离子是低丰度的。肌醇上的脂肪酰基部分也可以通过[M-H-二酰基甘油R3CO2H]-离子MS4的乘积离子光谱来鉴定，该离子产生一个与R4CO2H损失相对应的显著离子。在MS2谱中还观察到一个[M-H-酰基甘露糖]-离子，从而证实了2-O-甘露糖苷上的脂肪酸取代基的同一性。从MS2、MS3和MS4的多级产物离子谱中获得的组合信息允许指认从牛分枝杆菌卡介苗分离的混合物中单酰基和双酰基PIMs的复杂结构。

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 multiple-stage ion-trap mass spectrometric approaches towards to the structural characterization of the monoacyl-PIM (triacylated PIM) and the diacyl-PIM (tetracylated PIM), namely, the PIM (diacylated PIM) consisting of one or two additional fatty acid substituents attached to the glycoside, respectively, were described. While the assignment and confirmation of the fatty acid substituents on the glycerol backbone can be easily achieved by the methods described in the previous article, the identity of the glycoside moiety and its acylation state can be determined by the observation of a prominent acylglycoside ion arising from cleavage of the diacylglycerol moiety ([M - H - diacylglycerol]-) in the MS2 spectra of monoacyl-PIM and diacyl-PIM. The distinction of the fatty acid substituents on the 2-O-mannoside (i.e, R3CO2H) from that on the inositol (i.e., R4CO2H) is based on the findings that the MS3 spectrum of [M - H - diacylglycerol]- contains a prominent ion arising from further loss of the fatty acid at the 2-O-mannoside (i.e, the [M - H - diacylglycerol - R3CO2H]- ion); while the ion arising from loss of the fatty acid substituent at the inositol (i.e, the [M - H - diacylglycerol - R4CO2H]- ion) is of low abundance. The fatty acyl moiety on the inositol can also be identified by the product-ion spectrum from MS4 of the [M - H - diacylglycerol R3CO2H]- ion, which gives rise to a prominent ion corresponding to loss of R4CO2H. An [M - H - acylmannose]- ion was also observed in the MS2 spectra and thus, the identity of the fatty acid substituent attached to 2-O-mannoside can be confirmed. The combined information obtained from the multiple-stage product-ion spectra from MS2, MS3, and MS4 permit the assignment of the complex structures of monoacyl-PIMs and diacyl-PIMs in a mixture isolated from M. bovis Bacillus Calmette Guerin.