title: Probing melittin helix-coil equilibria in solutions and vesicles.
abstract: Melittin is a toxic, amphipathic peptide that rearranges from a random coil in solution to a helical structure upon binding to cell membranes or lipid vesicles. We have found that mutation of the valine at position five of the peptide to a phenylalanine or 3-nitrotyrosine induces aggregation and helix formation at low concentrations (20-80 microM). Donor-acceptor distances obtained from analyses of fluorescence energy transfer kinetics experiments with the 3-nitrotyrosine mutant indicate that both coil and helix structures are present in 2 and 20 microM aqueous solutions. The helical peptide population increases upon addition of phospholipid vesicles or in high ionic strength solutions.
authors.affiliation: Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hartings
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
authors.forename: Jay R
authors.initials: JR
authors.lastname: Winkler
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D008555:Melitten / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012996:Solutions; D013050:Spectrometry, Fluorescence
chemical_list: D012996:Solutions; D008555:Melitten