STRUCTURAL STUDY OF ACIDIC PHOSPHOLIPID BASIC HOMOPOLYPEPTIDE COMPLEXES BY P-31 AND C-13 SOLID-STATE NMR CHEMICAL-SHIFTS

A solid-state nuclear magnetic resonance (NMR) study for the structura l elucidation of acidic phospholipid-basic polypeptide complex powder samples is presented. C-13 cross-polarization magic angle spinning (CP /MAS) experiments of poly(L-lysine)/dipalmitoylphosphatidic acid (DPPA ) complex and poly(L-arginine)/DPPA complex powders were performed. Th e NMR spectra suggest that poly(L-lysine) forms a beta-sheet conformat ion on the surface of the DPPA membrane, whereas poly(L-arginine) form s an or-helix conformation. Further, changes in the chemical shift ten sors of the P-31 nucleus associated with the complex formation were ob served, allowing us to depict the geometry of the DPPA headgroup.