Spin probe clustering in human erythrocyte ghosts.
A model has been developed for 5-nitroxide stearate, I(12,3), distribution in human erythrocyte ghosts which accurately predicts ESR spectral alterations observed with increased probe/total lipid (P/L) at 37 degrees C. This spin probe occupies a class of high-affinity, noninteracting sites at low loading. Saturation occurs with increasing probe concentration, and, at higher loading, the probe inserts itself at initially dilute sites to form membrane-bound clusters of variable size. No 'low' probe remains at high P/L where all I(12,3) clusters in a 'concentrated' phase. This model allows determination of the dilute/clustered probe ratio, and shows that I(12,3) segregates in erythrocytes at what might otherwise be considered low P/L (e.g., 1/359). These findings validate the earlier use of empirical parameters to estimate probe sequestration in biological membranes.
Gordon
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LM
Looney
F D
FD
Curtain
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CC
D003497:Cyclic N-Oxides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004910:Erythrocyte Membrane; D006801:Humans; D008433:Mathematics; D013113:Spin Labels / Q000378:metabolism*; D014018:Tissue Distribution
D003497:Cyclic N-Oxides; D013113:Spin Labels; C005072:5-doxylstearic acid