Diffusion Studies of Redox-Sensitive Nitroxyl Spin Probes through Bilayer Lipid Membranes using 300 MHz Electron Spin Resonance Spectrometer
Authors: M. Kumara Dhas, Hideo Utsumi, Kazuhiro Ichikawa, Ken-ichi Yamada, Fuminori Hyodo, A. Jawahar, A. Milton Franklin Benial
Number of views: 340
Abstract: Electron spin resonance (ESR) studies were carried out for 2mM 14N-labeled deutrated 3-methoxycarbonyl-2,2,5,5-
tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) and 3–carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy (carboxy-PROXYL) in
pure water and various concentrations of liposomal solutions by using 300 MHz ESR spectrometer. The ESR parameters such
as the line width, hyperfine coupling constant, rotational correlation time, g-factor, partition parameter and permeability were
reported for the samples. The line width broadening was observed for MC-PROXYL and carboxy-PROXYL in liposomal
solution. The hyperfine coupling constant was observed for both nitroxyl spin probes. The permeable and impermeable nature
of nitroxyl spin probes was demonstrated. The rotational correlation time increases with increasing concentration of liposome.
The partition parameter increases with increasing concentration of liposome for MC-PROXYL, which indicates that the
nitroxyl spin probes diffuse into lipid membrane. The permeability (R) value decreases with increasing concentration of
liposome, which reveals that the increase of membrane permeability. The peaks correspond to lipid phase were observed for
MC-PROXYL in liposomal solution, but that peak was not resolved for carboxy-PROXYL. These results confirm the
permeable and the impermeable nature of nitroxyl spin probes.