title: Using two fluorescent probes to dissect the binding, insertion, and dimerization kinetics of a model membrane peptide.
abstract: Helix-helix association within a membrane environment represents one of the fundamental processes in membrane protein folding. However, studying the kinetics of such processes has been difficult because most membrane proteins are insoluble in aqueous solution. Here we present a stopped-flow fluorescence study of the membrane-interaction kinetics of a designed, water-soluble transmembrane (TM) peptide, anti-alpha(IIb), which is known to dimerize in phospholipid bilayers. We show that by using two fluorescent amino acids, tryptophan and p-cyanophenylalanine, we are able to kinetically dissect distinct phases in the peptide-membrane interaction, representing membrane binding, membrane insertion, and TM helix-helix association. Our results further show that the last process occurs on a time scale of seconds, indicating that the association of two TM helices is an intrinsically slow event.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Tang
authors.forename: Hang
authors.initials: H
authors.lastname: Yin
authors.forename: Jade
authors.initials: J
authors.lastname: Qiu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Tucker
authors.forename: William F
authors.initials: WF
authors.lastname: DeGrado
authors.forename: Feng
authors.initials: F
authors.lastname: Gai
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D005456:Fluorescent Dyes; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry*; D008954:Models, Biological; D015336:Molecular Probe Techniques; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D005456:Fluorescent Dyes; D008565:Membrane Proteins; D010455:Peptides