Oxygen profiles in membranes.
Transmembrane profiles of molecular oxygen in lipid bilayers are not only significant for membrane physiology and pathology, but also are essential to the determination of membrane protein structure by site-directed spin labeling. Oxygen profiles obtained with spin-labeled lipid chains have a Boltzmann sigmoidal dependence on the depth into each lipid leaflet, which represents a two-compartment distribution between outer and inner regions of the membrane, with a transfer free energy that depends linearly on distance from the dividing planes. Transmembrane profiles for intramembrane polarity, and for water penetration into the membrane, have an identical form, but are of the reverse sign. Comparison with recently published oxygen profiles from a site-specifically spin-labeled alpha-helical transmembrane peptide validates the use of spin-labeled lipids for all these profiles and provides the necessary bridge to generate the full bilayer from a single lipid leaflet.
Marsh
Derek
D
Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie, 37070 Göttingen, Germany. dmarsh@gwdg.de
Dzikovski
Boris G
BG
Livshits
Vsevolod A
VA
D001703:Biophysics / Q000379:methods*; D002462:Cell Membrane / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D008563:Membrane Lipids / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D013113:Spin Labels; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D008051:Lipid Bilayers; D008055:Lipids; D008563:Membrane Lipids; D010455:Peptides; D010743:Phospholipids; D013113:Spin Labels; D014867:Water; D010100:Oxygen