Bacteriorhodopsin/amphipol Complexes: Structural and Functional Properties

Biophys J. 2008 May 1;94(9):3523-37. doi: 10.1529/biophysj.107.121848. Epub 2008 Jan 11.

Abstract

The membrane protein bacteriorhodopsin (BR) can be kept soluble in its native state for months in the absence of detergent by amphipol (APol) A8-35, an amphiphilic polymer. After an actinic flash, A8-35-complexed BR undergoes a complete photocycle, with kinetics intermediate between that in detergent solution and that in its native membrane. BR/APol complexes form well defined, globular particles comprising a monomer of BR, a complete set of purple membrane lipids, and, in a peripheral distribution, approximately 2 g APol/g BR, arranged in a compact layer. In the absence of free APol, BR/APol particles can autoassociate into small or large ordered fibrils.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Bacteriorhodopsins / chemistry*
  • Bacteriorhodopsins / metabolism*
  • Chromatography, Gel
  • Colloids / chemistry
  • Color
  • Halobacterium salinarum / metabolism
  • Lipids / chemistry
  • Microscopy, Electron
  • Neutron Diffraction
  • Polymers / chemistry*
  • Polymers / metabolism*
  • Propylamines / chemistry*
  • Propylamines / metabolism*
  • Protein Structure, Secondary
  • Purple Membrane / chemistry
  • Purple Membrane / metabolism
  • Scattering, Small Angle
  • Thioglucosides / chemistry
  • Ultracentrifugation

Substances

  • Bacterial Proteins
  • Colloids
  • Lipids
  • Polymers
  • Propylamines
  • Thioglucosides
  • amphipol A8-35
  • Bacteriorhodopsins
  • n-octyl-beta-D-thioglucopyranoside