title: Analyzing heat capacity profiles of peptide-containing membranes: cluster formation of gramicidin A.
abstract: The analysis of peptide and protein partitioning in lipid membranes is of high relevance for the understanding of biomembrane function. We used statistical thermodynamics analysis to demonstrate the effect of peptide mixing behavior on heat capacity profiles of lipid membranes with the aim to predict peptide aggregation from c(P)-profiles. This analysis was applied to interpret calorimetric data on the interaction of the antibiotic peptide gramicidin A with lipid membranes. The shape of the heat capacity profiles was found to be consistent with peptide clustering in both gel and fluid phase. Applying atomic force microscopy, we found gramicidin A aggregates and established a close link between thermodynamics data and microscopic imaging. On the basis of these findings we described the effect of proteins on local fluctuations. It is shown that the elastic properties of the membrane are influenced in the peptide environment.
authors.affiliation: Membrane Biophysics and Thermodynamics Group, Max-Planck-Institute for Biophysical Chemistry, 37070 Göttingen, Germany.
authors.forename: V P
authors.initials: VP
authors.lastname: Ivanova
authors.forename: I M
authors.initials: IM
authors.lastname: Makarov
authors.forename: T E
authors.initials: TE
authors.lastname: Schäffer
authors.forename: T
authors.initials: T
authors.lastname: Heimburg
mesh_terms: D003198:Computer Simulation; D006096:Gramicidin / Q000737:chemistry*; D006358:Hot Temperature; D008081:Liposomes / Q000737:chemistry*; D046911:Macromolecular Substances; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011485:Protein Binding; D011487:Protein Conformation; D013814:Thermal Conductivity
chemical_list: D008081:Liposomes; D046911:Macromolecular Substances; D008563:Membrane Lipids; D008565:Membrane Proteins; D006096:Gramicidin