VIBRATIONALLY COOLED MALDI, TLC MALDI FTMS FOR GANGLIOSIDES, NEUTRAL GLYCOLIPIDS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们先前开发的薄层色谱（TLC）与振动冷却（VC）MALDI-FTMS直接耦合的方法允许简单处理具有FT高分辨率的TLC，其不受TLC板的不规则表面的影响。使用振动冷却对于神经节苷脂的稳定和检测是必要的。 该技术的优化导致了直接从TLC板解吸的离子的高灵敏度。在自行研制的FT-ICR质谱仪上，采用倍频355 nm的Nd：YAG（UV）激光器、337 nm的氮激光器和2.94nm的Er：YAG（IR）激光器，进行了MALDI-FTMS实验。碰撞冷却气体在解吸-电离事件期间升高离子源中的压力。使用从不锈钢板上解吸的标准品作为校准品，对相邻样品进行内部校准（InCAS）。从TLC上解吸的神经节苷脂的灵敏度低fmol（分离前在TLC板上点样的总量）。InCAS的使用已证明，分析物从不均匀的TLC板表面解吸后，准确度不受影响，神经节苷脂标准品的质量准确度通常为0.5-1.5 ppm。研究了冷却气体类型、与电离-脱附过程相协调的气体脉冲、冷却气体压力、气体脉冲持续时间、不同的激光强度、聚焦和光束轮廓等参数对分子稳定化的影响。以尿素为基质的神经节苷脂的软IR-解吸，连同在振动冷却源中的冷却，消除了唾液酸损失。所开发的方法正在应用于生物系统的样品，如全脑神经节苷脂混合物，利什曼原虫脂质，神经元细胞的富含神经节苷脂的脂筏和人乳中的HIV保护糖脂。红外多光子解离（CO2激光，10.7 μ m）和SORI-CAD被用作补充解离方法。在这一年中，对原有的VC-MALDI系统进行了重建，并对其性能进行了重新评估。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Our previously developed method of direct coupling of thin layer chromatography (TLC) with Vibrationally-Cooled (VC) MALDI-FTMS allows simple handling of TLC with FT high resolution which is not affected by the irregular surface of the TLC plate. Use of vibrational cooling is necessary for ganglioside stabilization and detection. Optimization of this technique has led to high sensitivity for the ions desorbed directly from the TLC plate. MALDI-FTMS experiments have been carried out on our home-built FT-ICR mass spectrometer with 7T magnet and Nd:YAG (UV) laser, frequency tripled to 355 nm, nitrogen laser (337 nm) and Er:YAG (IR) laser (2.94 um). The collision cooling gas raises the pressure in the ion source during the desorption-ionization event. Internal Calibration on Adjacent Samples (InCAS) is performed using standards desorbed from the stainless steel plate as calibrants. The sensitivity the has been obtained for the gangliosides desorbed from TLC is low fmol (total amount spotted on a TLC plate prior to separation). The use of InCAS has demonstrated that accuracy is not affected upon desorption of the analyte from uneven TLC plate surface and mass accuracy is usually 0.5-1.5 ppm for ganglioside standards. The effect of several parameters on molecule stabilization was studied, such as the type of the cooling gas, gas pulsing coordinating with ionization-desorption event, cooling gas pressure, duration of gas pulse, different laser intensities, focusing and beam profile. Soft IR-desorption of the gangliosides with urea as the matrix, together with cooling in the Vibrationally Cooled source eliminated sialic acid loss. The developed method is being applied to the samples from biological systems such as whole brain ganglioside mix, Leishmania lipids, ganglioside-rich lipid rafts from neuronal cells and HIV-protective glycolipids from human milk. Infrared multiphoton dissociation (CO2 laser, 10.7 um) and SORI-CAD are being used as complementary dissociation methods. During this year the original VC-MALDI system was rebuilt and its performance is being re-evaluated.