Transmembrane segments of proteins are often flanked by lysine residues. The side chains of these residues may snorkel, i.e. they may bury themselves with their aliphatic part in the hydrophobic region of the lipid bilayer, while positioning the charged amino group in the more polar interface. Here we estimate the free energy cost of snorkeling from thermodynamical calculations based on studies with synthetic transmembrane peptides [Strandberg et al. (2002) Biochemistry 41, 7190–7198]. The value is estimated to be between 0.07 and 0.7 kcal mol⁻¹ for a lysine side chain. This very low value indicates that snorkeling may be a common process, which should be taken into consideration both in experimental and in theoretical studies on protein–lipid interactions.

NMR is a versatile tool for studying interactions between antimicrobial peptides and lipid membranes. Different approaches using both liquid state and solid state NMR are outlined here, with an emphasis on solid state NMR methods, to study the structures of antimicrobial peptides in lipid bilayers as well as the effect of these peptides on model membranes. Different NMR techniques for observing both peptides and lipids are explained, including ²H, ¹³C, ¹⁵N, and ¹⁹F labels, or natural abundance ¹H, ¹³C, or ³¹P. Previous studies in the field are extensively reviewed in easily accessible tables. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 23A: 89–120, 2004.