STRUCTURE AND DYNAMICS OF THE ANTIBIOTIC PEPTIDE PGLA IN MEMBRANES BYSOLUTION AND SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

PGLa, a 21-residue member of the magainin family of antibiotic peptide s, is shown to be helical between residues 6 and 21 when associated wi th detergent micelles by multidimensional solution nuclear magnetic re sonance (NMR) spectroscopy. Solid-state NMR experiments on specificall y N-15-labeled peptides in oriented phospholipid bilayer samples show that the helix axis is parallel to the plane of the bilayers, N-15 sol id-state NMR powder pattern line shapes obtained on unoriented samples demonstrate that the amino-terminal residues are highly mobile and th at the fluctuations of backbone sites decrease from Ala6 toward the ca rboxy terminus. The powder pattern observed for N-15-labeled Ala20 is essentially that expected for a rigid site. These findings are similar to those for the 23-residue magainin2 peptide in membrane environment s.