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Contryphan sequence diversity: Messy N-terminus processing, effects on chromatographic behaviour and mass
M Vijayasarathy1, Sanjeev Kumar1, M A Venkatesha1
1National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
Journal of Proteomics
|January 1, 2023
Summary
Contryphans, peptides from cone snail venom, are classified by proline positions in their disulfide loop. Anomalous LC profiles and mass spectral fragments offer rapid identification methods for these diverse peptides.
Area of Science:
- Biochemistry
- Peptidomics
- Venomics
Background:
- Contryphans are abundant peptides in cone snail venom, characterized by a single disulfide bond and a macrocyclic loop.
- Sequence diversity arises from proteolytic processing and post-translational modifications of precursor proteins.
- Proline residues at specific positions within the disulfide loop influence contryphan structure and dynamics.
Purpose of the Study:
- To classify contryphans based on sequence features, particularly proline residue occurrence.
- To investigate the relationship between contryphan sequence, conformational dynamics, and chromatographic behavior.
- To develop rapid diagnostic methods for identifying contryphans in crude venom using LC-MS/MS.
Main Methods:
- Analysis of a large dataset of contryphan sequences.
- Liquid Chromatography-Mass Spectrometry (LC-MS) analysis of diverse contryphans.
- Synthesis and analysis of analogs to delineate structural features responsible for anomalous behavior.
Main Results:
- Contryphan classification based on proline at positions 2 and 5 within the disulfide loop.
- Presence of Pro at position 2 and a D-residue at position 3 causes slow conformational dynamics and anomalous LC profiles.
- Non-canonical mass spectral fragments, generated by N-Cα bond cleavage, indicate Pro at position 5.
Conclusions:
- Anomalous LC profiles serve as a diagnostic for the Pro2-DXxx3 motif.
- Non-canonical mass spectral fragments are diagnostic for Pro at position 5.
- LC-ESI-MS/MS analysis of crude Conus venom enables rapid contryphan identification based on these diagnostic features.
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