The structure of the membrane‐binding 38 C‐terminal residues from bovine PP3 determined by liquid‐ and solid‐state NMR spectroscopy

The secondary structure and membrane‐associated conformation of a synthetic peptide corresponding to the putative membrane‐binding C‐terminal 38 residues of the bovine milk component PP3 was determined using 1H NMR in methanol, CD in methanol and SDS micelles, and 15N solid‐state NMR in planar phospholipid bilayers. The solution NMR and CD spectra reveal that the PP3 peptide in methanol and SDS predominantly adopts an α‐helical conformation extending over its entire length with a potential bend around residue 19. 15N solid‐state NMR of two PP3 peptides 15N‐labelled at the Gly7 and Ala32 positions, respectively, and dissolved in dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol phospholipid bilayers shows that the peptide is associated to the membrane surface with the amphipathic helix axis oriented parallel to the bilayer surface.