Protein-protein Interaction in Purple Membrane

Phys Rev Lett. 2009 Sep 18;103(12):128104. doi: 10.1103/PhysRevLett.103.128104. Epub 2009 Sep 18.


We present experimental evidence for a long-range protein-protein interaction in purple membrane (PM). The interprotein dynamics were quantified by measuring the spectrum of the acoustic phonons in the 2D bacteriorhodopsin (BR) protein lattice using inelastic neutron scattering. Phonon energies of about 1 meV were determined. The data are compared to an analytical model, and the effective spring constant for the interaction between neighboring protein trimers are determined to be k = 53 N/m. Additional, optical-like excitations at 0.45 meV were found and assigned to intraprotein dynamics between neighboring BR monomers.

MeSH terms

  • Bacteriorhodopsins / chemistry*
  • Bacteriorhodopsins / metabolism*
  • Neutron Diffraction
  • Protein Interaction Mapping
  • Purple Membrane / chemistry*
  • Purple Membrane / metabolism*
  • Thermodynamics


  • Bacteriorhodopsins