ISSN:
1432-1017
Keywords:
Key words Cyclopeptide
;
Surfactant
;
Interaction
;
Micelle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract The interaction of the cyclic decapeptide antibiotic gramicidin-S (GrS) with the nonionic detergent octaethylene glycol mono-n-dodecyl ether was studied by NMR spectroscopy. Detergent binding led to a slightly altered average conformation in the d-Phe side chains of the peptide. The changing diamagnetic shielding of nearby protons resulted in chemical shift variations, the largest effect being observed for the d-Phe C α proton. The continuous upfield shift of this proton resonance, indicating rapid exchange of the peptide between detergent-associated and unassociated states, was employed for an evaluation of the detergent/peptide aggregation equilibria. The nonlinear binding plot thus obtained was attributed to essentially different aggregational states, depending on the detergent/peptide ratio. The almost linear dependence of the spin-lattice relaxation rate and of the hydrogen-deuterium exchange rate on the fraction of detergent-associated GrS could be reconciled with a simple model, comprising binding of detergent monomers and cooperative binding of micelles at low and high detergent/peptide molar ratios, respectively. Thus, GrS provides a useful model for a study of backbone dynamics and water penetration in detergent- and membrane-bound peptides and proteins. The results will also be discussed with reference to the interaction of GrS with biological membranes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002490050196
