开发基于质谱的用于复杂生物样品中瓜氨酸化蛋白的大规模定性和定量分析策略
Mass spectrometric imaging (MSI) provides an attractive opportunity to detect and probe the molecular content of tissues in an anatomical context. To expand the mass range of a high resolution accurate mass (HRAM) MSI platform, we employed volatile matrices to produce multiply charged ions in MALDI source via laserspray ionization (LSI) and matrix assisted ionization in vacuum (MAIV) techniques on the MALDI Orbitrap platform. These new ionization techniques enabled substantial expansion of the mass range of the instrument and generated improved fragmentation efficiency compared to traditional MALDI-MS. To further enhance the chemical information extracted from in situ MALDI MSI experiments, we report on a multiplex-MSI method, which combines HRAM MSI technology with data dependent acquisition (DDA) tandem MS analysis in a single experiment. To improve the dynamic range and efficiency of in situ DDA, we introduce a novel gas-phase fractionation strategy prior to MS/MS scans, to decrease molecular complexity of tissue samples for enhanced peptidome coverage. In addition, the utility of a novel subatmospheric pressure (SubAP)/MALDI source coupled with a hybrid quadrupole-orbitrap mass spectrometer for in situ imaging of glycans from formalin-fixed paraffin-embedded (FFPE) tissue sections and its translation to clinical cancer tissue microarray analysis will be highlighted. Finally, to further improve the sensitivity of MALDI MSI, a photoactive compound, 2-nitrobenzaldehyde is used to initiate a nanosecond photochemical reaction (nsPCR). This nsPCR strategy enables enhanced neuropeptide identification and visualization from complex tissue samples through on-demand removal of surrounding matrices within nanoseconds. The utility of this new approach for in situ analysis of endogenous biomolecules is evaluated and demonstrated.
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2022-08-24
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