A solid-state NMR index of helical membrane protein structure and topology

J Magn Reson. 2000 May;144(1):150-5. doi: 10.1006/jmre.2000.2035.


The secondary structure and topology of membrane proteins can be described by inspection of two-dimensional (1)H-(15)N dipolar coupling/(15)N chemical shift polarization inversion spin exchange at the magic angle spectra obtained from uniformly (15)N-labeled samples in oriented bilayers. The characteristic wheel-like patterns of resonances observed in these spectra reflect helical wheel projections of residues in both transmembrane and in-plane helices and hence provide direct indices of the secondary structure and topology of membrane proteins in phospholipid bilayers. We refer to these patterns as PISA (polarity index slant angle) wheels. The transmembrane helix of the M2 peptide corresponding to the pore-lining segment of the acetylcholine receptor and the membrane surface helix of the antibiotic peptide magainin are used as examples.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antimicrobial Cationic Peptides*
  • Chemical Phenomena
  • Chemistry, Physical
  • Lipid Bilayers / chemistry*
  • Magainins
  • Magnetic Resonance Spectroscopy / methods*
  • Membrane Proteins / chemistry*
  • Nitrogen Isotopes
  • Peptides / chemistry*
  • Protein Structure, Secondary*
  • Xenopus Proteins*


  • Antimicrobial Cationic Peptides
  • Lipid Bilayers
  • Magainins
  • Membrane Proteins
  • Nitrogen Isotopes
  • Peptides
  • Xenopus Proteins
  • magainin 2 peptide, Xenopus