STRUCTURAL CHARACTERIZATION OF PHOSPHATIDYL-MYO-INOSITOL MANNOSIDES FROM

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 介绍了单酰化PIM（三酰化PIM）和双酰化PIM（四酰化PIM）的多级离子阱质谱表征方法，即分别在糖苷上附加一个或两个脂肪酸取代基的PIM（双酰化PIM）。虽然甘油主链上的脂肪酸取代基的分配和确认可以通过先前文章中描述的方法容易地实现，但是糖苷部分的身份及其酰化状态可以通过在单酰基-PIM和二酰基-PIM的MS 2光谱中观察由二酰基甘油部分（[M-H-二酰基甘油]-）裂解产生的突出酰基糖苷离子来确定。2-O-甘露糖苷上的脂肪酸取代基（即R3 CO2 H）与肌醇上的脂肪酸取代基（即，R4 CO2 H）是基于以下发现：[M-H-二酰基甘油]-的MS 3光谱含有由2-O-甘露糖苷处脂肪酸的进一步损失产生的显著离子（即，[M-H-二酰基甘油-R3 CO2 H]-离子）;而由肌醇上脂肪酸取代基的损失产生的离子（即[M-H-二酰基甘油-R4 CO2 H]-离子）丰度低。肌醇上的脂肪酰基部分也可以通过[M-H-二酰基甘油R3 CO2 H]-离子的MS 4的产物离子光谱来鉴别，其产生对应于R4 CO2 H损失的显著离子。在MS 2光谱中还观察到[M-H-酰基甘露糖]-离子，因此可以确认与2-O-甘露糖苷连接的脂肪酸取代基的身份。从MS 2、MS 3和MS 4的多阶段产物离子光谱获得的组合信息允许对从M分离的混合物中的单酰基-PIM和二酰基-PIM的复杂结构进行归属。牛卡介苗

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.