Document Detail

Microscopic Rates of Peptide-Phospholipid Bilayer Interactions from Single-Molecule Residence Times.
MedLine Citation:
PMID:  23151065     Owner:  NLM     Status:  Publisher    
The binding of glucagon-like peptide-1 (GLP-1) to a planar phospholipid bilayer is measured using single-molecule total-internal-reflection-fluorescence microscopy. From several reports in the literature, GLP-1 has been shown to be a random coil in free solution, adopting a folded, alpha-helix conformation when intercalated into membrane environments. Single-molecule fluorescence measurements of GLP-1 binding to supported lipid bilayers show evidence of two populations of membrane-associated molecules having different residence times, suggesting weakly adsorbed peptides and strongly bound peptides in the lipid bilayer. The path to and from a strongly bound (folded, intercalated) state should include the adsorbed state as an intermediate, so that the kinetics should correspond to a consecutive first-order reversible three-state model. In this work, the relationship between measured single-molecule residence times and the microscopic rates in a three-state kinetic model are derived and used to interpret the binding of GLP-1 to a supported lipid bilayer. The system of differential equations associated with the consecutive-three state kinetics scheme is solved, and the solution is applied to interpret histograms of single-molecule, GLP-1 residence times in terms of the microscopic rates in the sequential-step model. These microscopic rates are used to estimate the free energy barrier to adsorption, the fraction of peptides adsorbing to the membrane surface that successfully intercalate in the bilayer, the lifetime of inserted peptides in the membrane, and the free energy change of insertion into the lipid bilayer from the adsorbed state. The transition from a random coil in solution to a folded state in a membrane has been recognized as a common motif for insertion of membrane active peptides. Therefore, the relationships developed here should have wide application to the kinetic analysis of peptide/membrane interactions.
Grant A Myers; Daniel A Gacek; Eric M Peterson; Christopher B Fox; Joel M Harris
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-14
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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