Probing melittin helix-coil equilibria in solutions and vesicles.
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.
Hartings
Matthew R
MR
Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Gray
Harry B
HB
Winkler
Jay R
JR
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
D012996:Solutions; D008555:Melitten