title: Conformational mapping of a viral fusion peptide in structure-promoting solvents using circular dichroism and electrospray mass spectrometry.
abstract: The N-terminal domain of human immunodeficiency virus (HIV)-1 glycoprotein 41,000 (FP; residues 1-23; NH2-AVGIGALFLGFLGAAGSTMGARS-CONH2) is involved in the fusion and cytolytic processes underlying viral-cell infection. Here, we use circular dichroism (CD) spectroscopy, along with electrospray ionization (ESI) mass spectrometry and tandem (MS/MS) mass spectrometry during the course of hydrogen/deuterium exchange, to probe the local conformations of this synthetic peptide in two membrane mimics. Since amino acids that participate in defined secondary structure (i.e., alpha-helix or beta-sheet) exchange amido hydrogens more slowly than residues in random structures, deuterium exchange was combined with CD spectroscopy to map conformations to specific residues. For FP suspended in the highly structure-promoting solvent hexafluoroisopropanol (HFIP), CD spectra indicated high alpha-helix and disordered structures, whereas ESI and MS/MS mass spectrometry indicated that residues 5-15 were alpha-helical and 16-23 were disordered. For FP suspended in the less structure-promoting solvent trifluoroethanol (TFE), CD spectra showed lower alpha-helix, with ESI and MS/MS mass spectrometry indicating that only residues 9-15 participated in the alpha-helix. These results compare favorably with previous two-dimensional nuclear magnetic resonance studies on the same peptide.
authors.affiliation: Department of Pediatrics, Drew University-King Medical Center and UCLA, Los Angeles, California, USA. awaring@ucla.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Waring
authors.forename: P W
authors.initials: PW
authors.lastname: Mobley
authors.forename: L M
authors.initials: LM
authors.lastname: Gordon
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D015700:HIV Envelope Protein gp41 / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D010449:Peptide Mapping; D011487:Protein Conformation; D012997:Solvents
chemical_list: D015700:HIV Envelope Protein gp41; D010446:Peptide Fragments; D012997:Solvents