Mass spectrometry (MS) using an electron multiplier for intact protein analysis remains limited. Because of the massive size and complex structure of proteins, the slow flight speed of their ions results in few secondary electrons and thus low detection sensitivity and poor spectral resolution. Thus, we present a compact ion trap-mass spectrometry approach to directly detect ion packets and obtain the high-resolution molecular signature of proteins. The disturbances causing deviations of ion motion and mass conversion have been clarified in advance. The radio frequency waveform used to manipulate ions is proposed to be a sequence of constant-frequency steps, interconnected by short time-outs, resulting in least dispersive distortion. Furthermore, more such constant-phase conjunctions are arranged in each step to compensate for fluctuations resulting from defects in the system and operation. In addition, two auxiliary pulses are generated in the right phase of each step to select ions of a specific secular state to detect one clean and sharp spectral line.This study demonstrates a top-down approach for the MS measurement of cytochrome C molecules, resulting in a spectral profile of the protein in its natural state at a resolution of 20 Da. Additionally, quick MS scans of other proteins were performed.

中文翻译：

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通过相位调制、步进频率扫描离子阱质谱进行高分辨率完整蛋白质分析


使用电子倍增器进行完整蛋白质分析的质谱 (MS) 仍然有限。由于蛋白质体积大、结构复杂，其离子飞行速度慢，二次电子少，检测灵敏度低，光谱分辨率差。因此，我们提出了一种紧凑的离子阱质谱方法来直接检测离子包并获得蛋白质的高分辨率分子特征。导致离子运动和质量转换偏差的扰动已被提前阐明。用于操纵离子的射频波形被建议为一系列恒定频率步骤，通过短超时互连，从而产生最小的色散失真。此外，在每一步中还设置更多这样的恒相位连接，以补偿由于系统和操作缺陷而产生的波动。此外，在每个步骤的正确阶段生成两个辅助脉冲，以选择特定长期状态的离子来检测一条干净而清晰的谱线。这项研究展示了一种自上而下的细胞色素 C 分子 MS 测量方法，结果天然状态下蛋白质的光谱图，分辨率为 20 Da。此外，还对其他蛋白质进行了快速 MS 扫描。