Comparative analysis of ceramide structural modification found in fungal cerebrosides by electrospray tandem mass spectrometry with low energy collision-induced dissociation of Li+ adduct ions
Comparative analysis of ceramide structural modification found in fungal cerebrosides by electrospray tandem mass spectrometry with low energy collision-induced dissociation of Li+ adduct ions
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DOI：
10.1002/(sici)1097-0231(20000415)14:7
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发表时间：
2000-01-01
影响因子：
2
通讯作者：
Takahashi, HK
中科院分区：
文献类型：
--
作者：
Levery, SB;Toledo, MS;Takahashi, HK
真菌脑苷脂（单己糖神经酰胺，或 CMH）表现出许多哺乳动物鞘糖脂中未发现的神经酰胺结构修饰，这对其完整表征提出了额外的挑战。研究发现，Li+阳离子化与电喷雾电离质谱和低能碰撞诱导解离串联质谱 (ESI-MS/CID-MS) 相结合，对于复杂真菌 CMH 的详细结构分析特别有效，尤其是混合物中丰度极低的微量成分。在相似条件下分析的相同 CMH 组分的 [M + Li](+) 相对于 [M + Na](+) 的碰撞诱导解离中，观察到灵敏度和碎片显着增加。首先通过分析各种标准 CMH 来系统评估特定修饰对片段化的影响，这些 CMH 逐渐表达更多功能化的神经酰胺，其中包括具有非羟基和 2-羟基脂肪 N-酰化的牛脑半乳糖脑苷脂； [0071] 植物葡糖脑苷脂除了鞘氨醇碱基的(E)-Delta(4)不饱和度外还具有(E/Z)-Delta(8)；已知一对真菌脑苷脂通过鞘氨醇部分上的支链 9-甲基基团进一步修饰，并具有完全饱和或 (E)-Delta(3) 不饱和的 2-羟基脂肪 N-酰基部分。然后将该方法应用于非致病性菌丝真菌黑曲霉的 CMH 组分中主要和次要成分的表征；以及来自白色念珠菌（酵母形式）的致病菌株；三个隐球菌属。 （所有酵母形式）；和巴西副球孢子菌（酵母和菌丝体形式）。所有受检物种的主要成分主要（且广泛）差异在于 2-羟基脂肪 N-酰基 Delta(3) 不饱和度水平，但在次要成分中，根据鞘氨醇或 N-酰基链长度的差异，以及是否存在鞘氨醇 Bs 不饱和度或 9-甲基，观察到了显着程度的额外结构多样性。一些变体是同量异位的，并且并非均匀存在于所有物种中，这证实需要进行 MS/CID-MS 分析来全面表征真菌 CMH 组分中的所有成分。观察到的神经酰胺分布的多样性可能反映了真菌之间在脑苷脂生物合成和功能方面的显着物种特异性差异。版权所有 (C) 2000 John Wiley & Sons, Ltd.
Fungal cerebrosides (monohexosylceramides, or CMHs) exhibit a number of ceramide structural modifications not found in mammalian glycosphingolipids, which present additional challenges for their complete characterization. The use of Li+ cationization, in conjunction with electrospray ionization mass spectrometry and low energy collision-induced dissociation tandem mass spectrometry (ESI-MS/CID-MS), was found to be particularly effective for detailed structural analysis of complex fungal CMHs, especially minor components present in mixtures at extremely low abundance. A substantial increase in both sensitivity and fragmentation was observed on collision-induced dissociation of [M + Li](+) versus [M + Na](+) of the same CMH components analyzed under similar conditions. The effects of particular modifications on fragmentation were first systematically evaluated by analysis of a wide variety of standard CMHs expressing progressively more functionalized ceramides, These included bovine brain galactocerebrosides with non-hydroxy and 2-hydroxy fatty N-acylation; a plant glucocerebroside having (E/Z)-Delta(8) in addition to (E)-Delta(4) unsaturation of the sphingoid base; and a pair of fungal cerebrosides known to be further modified by a branching 9-methyl group on the sphingoid moiety, and to have a 2-hydroxy fatty N-acyl moiety either fully saturated or (E)-Delta(3) unsaturated. The method was then applied to characterization of both major and minor components in CMH fractions from a non-pathogenic mycelial fungus, Aspergillus niger; and from pathogenic strains of Candida albicans (yeast form); three Cryptococcus spp. (all yeast forms); and Paracoccidioides brasiliensis (both yeast and mycelium forms). The major components of all species examined differed primarily (and widely) in the level of 2-hydroxy fatty N-acyl Delta(3) unsaturation, but among the minor components a significant degree of additional structural diversity was observed, based on differences in sphingoid or N-acyl chain length, as well as on the presence or absence of the sphingoid Bs unsaturation or 9-methyl group. Some variants were isobaric, and were not uniformly present in all species, affirming the need for MS/CID-MS analysis for full characterization of all components in a fungal CMH fraction. The diversity in ceramide distribution observed may reflect significant species-specific differences among fungi with respect to cerebroside biosynthesis and function. Copyright (C) 2000 John Wiley & Sons, Ltd.