REDOR NMR on a hydrophobic peptide in oriented membranes

A method is presented for the calculation of REDOR dephasing for specifical ly labeled membrane-spanning peptides in uniformly aligned lipid bilayers u nder magic angle oriented sample spinning (MAOSS) conditions. Numerical sim ulations are performed for dephasing of C-13 Signal by N-15 when the labels are placed in an cy-helical peptide at the carbonyl of residue (i) and ami de nitrogen of residue (i + 2) to show the dependency of REDOR echo intensi ty on the peptide tilt angle relative to the membrane normal. The approach was applied to the labeled transmembrane domain of phospholamban ([N-15-Leu (37), C-13-Leu(39)]PLB(TM)) incorporated into dimyristoylphosphatidylcholin e bilayers. The dephasing observed for a random membrane dispersion showed that the peptide was cy-helical in the region including the two labels, and dephasing in oriented membranes showed that the peptide helix was tilted b y 25 degrees +/- 7 degrees relative to the bilayer normal. These results ag ree with those obtained by other spectroscopic methods. 2000 AcademicPress.