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Oxygen transport parameter in membranes as deduced by saturation recovery measurements of spin-lattice relaxation times of spin labels. Proc Natl Acad Sci U S A 1982 Mar;79(6):1854-8

Date

03/01/1982

Pubmed ID

6952236

Pubmed Central ID

PMC346079

DOI

10.1073/pnas.79.6.1854

Abstract

Spin-lattice relaxation time (T1) measurements of nitroxide radical spin labels in membranes have been made by using the saturation-recovery technique. Stearic acid and sterol-type labels were used as probes of dimyristoylphosphatidylcholine liposomes from 0 degrees C to 36 degrees C. In the absence of oxygen, the range of variation of T1 over all samples and conditions is about a factor of 3. Heisenberg exchange between oxygen and spin labels is an effective T1 mechanism for the spin labels. The full range of variation of T1 in the presence of air is about a factor of 100. It is suggested that the oxygen transport parameter W = T1(-1) (air) - T1(-1) (N2) is a useful new monitor of membrane fluidity that reports on translational diffusion of small molecules. The values of W change at the prephase and main phase transitions and vary in complex ways. Arguments are advanced that the data are indicative of anisotropic translational diffusion of oxygen.

Author List

Kusumi A, Subczynski WK, Hyde JS

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

Diffusion
Liposomes
Membrane Fluidity
Membrane Lipids
Nitrogen
Oxygen
Spin Labels
Temperature