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Sequencing of T-Superfamily Conotoxins from Conus virgo: Pyroglutamic Acid Identification and Disulfide Arrangement by MALDI Mass Spectrometry
- Source :
- Journal of the American Society for Mass Spectrometry. (8):1396-1404
- Publisher :
- American Society for Mass Spectrometry. Published by Elsevier B.V.
-
Abstract
- De novo mass spectrometric sequencing of two Conus peptides, Vi1359 and Vi1361, from the vermivorous cone snail Conus virgo, found off the southern Indian coast, is presented. The peptides, whose masses differ only by 2 Da, possess two disulfide bonds and an amidated C-terminus. Simple chemical modifications and enzymatic cleavage coupled with matrix assisted laser desorption ionization (MALDI) mass spectrometric analysis aided in establishing the sequences of Vi1359, ZCCITIPECCRI-NH(2), and Vi1361, ZCCPTMPECCRI-NH(2), which differ only at residues 4 and 6 (Z = pyroglutamic acid). The presence of the pyroglutamyl residue at the N-terminus was unambiguously identified by chemical hydrolysis of the cyclic amide, followed by esterification. The presence of Ile residues in both the peptides was confirmed from high-energy collision induced dissociation (CID) studies, using the observation of w(n)- and d(n)-ions as a diagnostic. Differential cysteine labeling, in conjunction with MALDI-MS/MS, permitted establishment of disulfide connectivity in both peptides as Cys2-Cys9 and Cys3-Cys10. The cysteine pattern clearly reveals that the peptides belong to the class of T-superfamily conotoxins, in particular the T-1 superfamily.
- Subjects :
- chemistry.chemical_classification
Chromatography
biology
Chemistry
Stereochemistry
Conus Snail
Mass spectrometry
biology.organism_classification
Cyclic peptide
Conus virgo
Pyrrolidonecarboxylic Acid
Matrix-assisted laser desorption/ionization
chemistry.chemical_compound
Structural Biology
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Conus
Animals
Conotoxin
Pyroglutamic acid
Amino Acid Sequence
Conotoxins
Spectroscopy
Cysteine
Subjects
Details
- Language :
- English
- ISSN :
- 10440305
- Issue :
- 8
- Database :
- OpenAIRE
- Journal :
- Journal of the American Society for Mass Spectrometry
- Accession number :
- edsair.doi.dedup.....7993657896eeb87b2592973d83e1b21f
- Full Text :
- https://doi.org/10.1016/j.jasms.2007.04.009