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Conformational study of a new SGTx1 neurotoxin from the spider Scodra griseipes using mass spectrometry
Author(s) -
Marvin Laure,
Lange Catherine
Publication year - 2001
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.261
Subject(s) - chemistry , mass spectrometry , dithiothreitol , electrospray ionization , time of flight mass spectrometry , tandem mass spectrometry , sample preparation in mass spectrometry , protein mass spectrometry , protonation , chromatography , analytical chemistry (journal) , ionization , organic chemistry , ion , enzyme
SGTx1 is a new neurotoxin from the venom of Scodra griseipes . Because of the small quantity of this natural peptide available, mass spectrometry was used to obtain information on its higher‐order structure. The kinetics of reduction by 1,4‐dithiothreitol (DTT) was monitored by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), and showed that one of the three disulfide bridges was appreciably more accessible to the DTT. Studies based on the charge state distribution (CSD) and H/D exchange of the non‐reduced peptide, under neutral and acidic conditions, were performed using electrospray mass spectrometry (ES‐MS). In neutral solution, SGTx1 showed a maximum charge state of four compared with seven potentially protonated basic residues, and all labile hydrogens were exchanged. However, under acidic conditions, a maximum charge state of only five was observed, and four of the labile hydrogens could not be deuterated. These observations are interpreted in terms of a rigid structure maintained by the disulfide bridges, which can be temporarily relaxed by disulfide bridge scrambling only at higher pH values. Copyright © 2001 John Wiley & Sons, Ltd.