Probing the kinetics of membrane-mediated helix folding.
The kinetics of peptide-membrane association have been studied previously using stopped-flow tryptophan fluorescence; however, such experiments do not directly report the coil-to-helix transition process, which is a hallmark of peptide-membrane interaction. Herein, we report a new method for directly assessing the kinetics of the helix formation accompanied by the peptide-membrane association. This method is based on the technique of fluorescence resonance energy transfer (FRET) and an amino acid FRET pair, p-cyano-L-phenylalanine and tryptophan. To demonstrate the utility of this method, we have studied the membrane-mediated helix folding dynamics of a mutant of magainin 2, an antibiotic peptide found in the skin of the African clawed frog, Xenopus laevis. Our results indicate that the coil-to-helix transition occurs during the binding of the peptide to the lipid vesicle (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)], 3:1, wt/wt) but prior to the full insertion of the peptide into the hydrophobic region of the lipid bilayers.
Tucker
Matthew J
MJ
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Tang
Jia
J
Gai
Feng
F
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008956:Models, Chemical; D011487:Protein Conformation; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014982:Xenopus laevis
D008567:Membranes, Artificial