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Structural characterization of methionine and leucine enkephalins by hydrogen/deuterium exchange and electrospray ionization tandem mass spectrometry
Author(s) -
Cai Xianmei,
Dass Chhabil
Publication year - 2004
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.1739
Subject(s) - chemistry , hydrogen–deuterium exchange , electrospray ionization , dimer , tandem mass spectrometry , mass spectrometry , protein mass spectrometry , monomer , electrospray , crystallography , stereochemistry , chromatography , organic chemistry , polymer
Conformational changes in two endogenous opioid active pentapeptides methionine enkephalin (Met‐enk) and leucine enkephalin (Leu‐enk) induced by trifluoroethanol (TFE) were identified using hydrogen/deuterium exchange (HDX), coupled with electrospray ionization (ESI) mass spectrometry. The exchange features in individual amino acid residues were characterized by acquiring tandem mass spectra of the deuterated peptides. The exact identity of the labile hydrogens involved in HDX reveals that the monomer forms of both peptides adopt an unfolded conformation in aqueous solvent, but prefer the 5→2 β ‐turn secondary structure under the membrane‐mimetic environment. The ESI mass spectra of Met‐enk and Leu‐enk also reveal that the dimer structure of these peptides coexists with the monomer conformation. The extent of the dimer structure is dependent on the peptide concentration and nature of the solvent. The non‐polar solvents facilitate the dimer formation. Copyright © 2004 John Wiley & Sons, Ltd.