Document Detail

De novo sequencing and disulfide mapping of a bromotryptophan-containing conotoxin by Fourier transform ion cyclotron resonance mass spectrometry.
MedLine Citation:
PMID:  17134143     Owner:  NLM     Status:  MEDLINE    
T-1-family conotoxins belong to the T-superfamily and are composed of 10-17 amino acids. They share a common cysteine framework and disulfide connectivity and exhibit unusual posttranslational modifications, such as tryptophan bromination, glutamic acid carboxylation, and threonine glycosylation. We have isolated and characterized a novel peptide, Mo1274, containing 11 amino acids, that shows the same cysteine pattern, -CC-CC, and disulfide linkage as those of the T-1-family members. The complete sequence, GNWCCSARVCC, in which W denotes bromotryptophan, was derived from MS-based de novo sequencing. The FT-ICR MS/MS techniques of electron capture dissociation (ECD), infrared multiphoton dissociation, and collision-induced dissociation served to detect and localize the tryptophan bromination. The bromine contributes a distinctive isotopic distribution in all fragments that contain bromotryptophan. ECD fragmentation results in the loss of bromine and return to the normal isotopic distribution. Disulfide connectivity of Mo1274, between cysteine pairs 1-3 and 2-4, was determined by mass spectrometry in combination with chemical derivatization employing tris(2-carboxyethyl)phosphine, followed by differential alkylation with N-ethylmaleimide and iodoacetamide. The ECD spectra of the native and partially modified peptide reveal a loss of bromine in a process that requires the presence of a disulfide bond.
Sudarslal Sadasivan Nair; Carol L Nilsson; Mark R Emmett; Tanner M Schaub; Konkallu Hanumae Gowd; Suman S Thakur; K S Krishnan; Padmanabhan Balaram; Alan G Marshall
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Analytical chemistry     Volume:  78     ISSN:  0003-2700     ISO Abbreviation:  Anal. Chem.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-11-30     Completed Date:  2007-02-09     Revised Date:  2014-09-17    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8082-8     Citation Subset:  IM    
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MeSH Terms
Amino Acid Sequence
Bromides / chemistry*
Chromatography, High Pressure Liquid
Conotoxins / analysis*,  chemistry*
Disulfides / analysis*,  chemistry*
Mass Spectrometry
Peptides / chemistry,  isolation & purification
Spectroscopy, Fourier Transform Infrared / methods*
Tryptophan / analysis,  chemistry*
Grant Support
Reg. No./Substance:
0/Bromides; 0/Conotoxins; 0/Disulfides; 0/Peptides; 8DUH1N11BX/Tryptophan

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