Spin label EPR studies of the effect of gramicidin S on lipid chain dynamics

M. Kiricsi, L. I. Horváth, L. Dux, T. Páli

Research output: Article

5 Citations (Scopus)

Abstract

The effect of gramicidin S (GS) on acyl chain dynamics of 14-doxylstearic acid spin label (14-SASL) monitoring the centre of dimyristoylphosphatidylcholine (DMPC) bilayers was studied with electron paramagnetic resonance (EPR) spectroscopy. The Chain-melting transition of DMPC was shifted down and broadened monotonously by several degrees with increasing peptide concentration in the range of lipid/peptide ratios of 1/p=5/1-15/1. The effective rotational correlation time τeff of 14-SASL became larger with increasing amounts of peptide bound to fluid membranes of DMPC. From the dependence of τeff on the lipid/peptide molar ratio it was estimated that about 10 DMPC molecules per monomer GS are involved in non-covalent peptide-lipid interaction. Optimized spectral subtractions showed that, well above the chain-melting transition, 90% of the EPR spectral intensity of the spin-labeled peptide-lipid complex (1/p=5/1) originated from spectra recorded in bilayers (without peptide) at lower temperature. This was not the case 6°C above the phase transition where two components with comparable intensities were detected. The two components were identified as different motional modes of the label molecules, rather than distinct mobile/immobile lipid populations.

Original languageEnglish
Pages (from-to)469-475
Number of pages7
JournalJournal of Molecular Structure
Volume563-564
DOIs
Publication statusPublished - máj. 28 2001

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ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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