Direct Identification of Intact Proteins Using a Low-Resolution Mass Spectrometer with CIDⁿ/ETnoD

Area of Science:

• Proteomics
• Mass Spectrometry
• Analytical Chemistry

Background:

• Proteomics is a rapidly growing field with intact protein identification as a key area.
• Low-resolution mass spectrometry presents challenges for accurate intact protein identification compared to high-resolution methods.

Purpose of the Study:

• To investigate the capability of identifying intact proteins using collision-induced dissociation (CID) and electron transfer without dissociation (ETnoD).
• To develop and validate a novel method combining CID and ETnoD for enhanced protein sequencing.

Main Methods:

• Utilized myoglobin as a model protein for testing.
• Generated stable product ions using CID and identified them with ETnoD.
• Employed a sequential charge-reduced precursor ion (CRI) generation strategy with ETnoD.
• Developed a multistage protocol termed CIDⁿ/ETnoD, combining CID and ETnoD for validation.

Main Results:

• Demonstrated the successful generation of stable product ions using CID.
• Showcased the ability of ETnoD to identify product ions and determine fragment charges and sequences.
• Validated the CIDⁿ/ETnoD protocol on several intact proteins, achieving multiple sequence identifications.

Conclusions:

• The CIDⁿ/ETnoD method enhances the identification of intact proteins using low-resolution mass spectrometry.
• This approach offers a robust strategy for detailed protein sequence analysis and validation.