Send to

Choose Destination
See comment in PubMed Commons below
Biophys J. 2003 Aug;85(2):1005-12.

Oxygen permeation profile in lipid membranes: comparison with transmembrane polarity profile.

Author information

Max-Planck-Institut für biophysikalische Chemie, Abt. Spektroskopie, 37070 Göttingen, Germany.


Permeation of oxygen into membranes is relevant not only to physiological function, but also to depth determinations in membranes by site-directed spin labeling. Spin-lattice (T(1)) relaxation enhancements by air or molecular oxygen were determined for phosphatidylcholines spin labeled at positions (n = 4-14, 16) of the sn-2 chain in fluid membranes of dimyristoyl phosphatidylcholine, by using nonlinear continuous-wave electron paramagnetic resonance (EPR). Both progressive saturation and out-of-phase continuous-wave EPR measurements yield similar oxygen permeation profiles. With pure oxygen, the T(2)-relaxation enhancements determined from homogeneous linewidths of the linear EPR spectra are equal to the T(1)-relaxation enhancements determined by nonlinear EPR. This confirms that both relaxation enhancements occur by Heisenberg exchange, which requires direct contact between oxygen and spin label. Oxygen concentrates in the hydrophobic interior of phospholipid bilayer membranes with a sigmoidal permeation profile that is the inverse of the polarity profile established earlier for these spin-labeled lipids. The shape of the oxygen permeation profile in fluid lipid membranes is controlled partly by the penetration of water, via the transmembrane polarity profile. At the protein interface of the KcsA ion channel, the oxygen profile is more diffuse than that in fluid lipid bilayers.

[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science Icon for PubMed Central
    Loading ...
    Support Center