High-Resolution Intact Protein Analysis via Phase-Modulated, Stepwise Frequency Scan Ion Trap Mass Spectrometry

TL;DR

This paper introduces a new ion trap mass spectrometry method for high-resolution intact protein analysis, improving detection sensitivity and resolution.

Contribution

A novel phase-modulated, stepwise frequency scan ion trap mass spectrometry technique for intact protein analysis is proposed.

Findings

The method achieves a resolution of 20 Da for cytochrome C molecules in their natural state.

The approach reduces dispersive distortion and compensates for system and operational fluctuations.

Quick mass spectrometry scans of other proteins were successfully performed.

Abstract

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.

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