A Strategy for Peptide Sequence Confirmation
No single method answers every sequence-identity question. A strong confirmation strategy combines orthogonal evidence.
Intact mass
Confirms that the observed molecular mass is consistent with the expected composition.
Tandem MS
Provides fragment-level sequence evidence and can localize modifications.
Peptide mapping
Useful for larger peptides or proteins and for disulfide or modification localization.
Amino acid analysis
Supports composition but not residue order.
Chromatography
Can distinguish some sequence analogs, epimers, or conformers when mass alone cannot.
Special challenges
- leucine versus isoleucine
- D- versus L-residues
- sequence rearrangements
- disulfide isomers
- isobaric substitutions
- labile modifications
Frequently asked questions
Is intact mass enough for a short synthetic peptide?
It may be strong evidence but does not resolve every structural ambiguity.
Can MS/MS prove stereochemistry?
Generally not without specialized methods.
Why use a reference standard?
It provides comparative retention and spectral behavior.
Does high HPLC purity prove sequence?
No.
Key takeaways
Sequence confirmation is strongest when intact mass, fragment data, chromatographic behavior, and material history agree.
References
- Aebersold R, Mann M. Mass-spectrometric exploration of proteome structure and function. Nature. 2016.
- Gross JH. Mass Spectrometry: A Textbook. Springer.
TSMS Labs educational disclaimer: For laboratory research and educational purposes only. Not for human consumption. This content is not medical, clinical, or regulatory advice.