Faculty Collaboration Database

Oxygen permeability of thylakoid membranes: electron paramagnetic resonance spin labeling study. Biochim Biophys Acta 1998 Jul 20;1365(3):453-63

Date

08/26/1998

Pubmed ID

9711298

DOI

10.1016/s0005-2728(98)00098-x

Abstract

Oxygen transport in thylakoid membranes of spinach chloroplasts (Spinacia oleracea) has been studied by observing the collisions of molecular oxygen with spin labels, using line broadening electron paramagnetic resonance (EPR) spectroscopy. Stearic acid spin labels were used to probe the local oxygen diffusion-concentration product. The free radical moiety was located at various distances from the membrane surface, and collision rates were estimated from linewidths of the EPR spectra measured in the presence and absence of molecular oxygen. The profile of the local oxygen diffusion-concentration product across the membrane determined at 20 degrees C demonstrates that this product, at all membrane locations, is higher than the value measured in water. From the profile of the oxygen diffusion-concentration product, the membrane oxygen permeability coefficient has been estimated using the procedure developed earlier (W.K. Subczynski, J.S. Hyde, A. Kusumi, Proc. Natl. Acad. Sci. USA 86 (1989) 4474-4478). At 20 degrees C, the oxygen permeability coefficient for the lipid portion of the thylakoid membrane was found to be 39.5 cm s-1. This value is 20% higher than the oxygen permeability coefficient of a water layer of the same thickness as the thylakoid membrane. The high permeability coefficient implies that the oxygen concentration difference across the thylakoid membrane generated under the illumination of the leaf by saturating actinic light is negligible, smaller than 1 microM.

Author List

Ligeza A, Tikhonov AN, Hyde JS, Subczynski WK

Author

Witold K. Subczynski PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cell Membrane Permeability
Chloroplasts
Diglycerides
Electron Spin Resonance Spectroscopy
Galactolipids
Glycolipids
Oxygen
Spin Labels
Spinacia oleracea