REDOR NMR on a hydrophobic peptide in oriented membranes.
A method is presented for the calculation of REDOR dephasing for specifically labeled membrane-spanning peptides in uniformly aligned lipid bilayers under magic angle oriented sample spinning (MAOSS) conditions. Numerical simulations are performed for dephasing of (13)C signal by (15)N when the labels are placed in an alpha-helical peptide at the carbonyl of residue (i) and amide nitrogen of residue (i + 2) to show the dependency of REDOR echo intensity on the peptide tilt angle relative to the membrane normal. The approach was applied to the labeled transmembrane domain of phospholamban ([(15)N-Leu(37), (13)C-Leu(39)]PLBTM) incorporated into dimyristoylphosphatidylcholine bilayers. The dephasing observed for a random membrane dispersion showed that the peptide was alpha-helical in the region including the two labels, and dephasing in oriented membranes showed that the peptide helix was tilted by 25 degrees +/- 7 degrees relative to the bilayer normal. These results agree with those obtained by other spectroscopic methods.
Middleton
D A
DA
Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom. middleda@bioch.ox.ac.uk
Ahmed
Z
Z
Glaubitz
C
C
Watts
A
A
D002135:Calcium-Binding Proteins / Q000737:chemistry*; D003198:Computer Simulation; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D017433:Protein Structure, Secondary; D000099211:Phospholamban
D002135:Calcium-Binding Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D000099211:Phospholamban