Application of electron spin resonance for investigating peptide-lipid interactions, and correlation with thermodynamics

Peptide-lipid interactions can be investigated with spin-labelled lipid pro bes by using electron spin resonance (ESR) methods that have been developed for studying lipid-protein interactions with both integral and peripheral membrane proteins and also with surface-binding proteins that additionally penetrate the membrane. This approach has the advantage that a direct compa rison can be made with the databank of ESR results from the various types o f membrane protein. The appropriateness of the peptides as models for membr ane proteins, or for their specific segments, can then be assessed. Further , differences in behaviour can be readily identified, as for example in the case of surface-active cytolytic or fusogenic peptides. Comparison with th ermodynamic predictions for membrane insertion provides a useful adjunct to the spin-label method.