Physical properties of lipid bilayers from EPR spin labeling and their influence on chemical reactions in a membrane environment

The influence of a variety of microenvironmental factors on the inherent reactivity of membrane-located reagents is poorly understood. A goal of this review is to provide detailed profiles of membrane properties, including hydrophobicity, oxygen and nitric oxide solubility and diffusion rates, bilayer penetration of metal ions and metal-ion complexes, and membrane order and fluidity, that can be obtained with EPR spin-labeling methods. These properties can drastically vary with membrane composition, membrane depth, and membrane domain formation, influencing the fate of chemical reactions that occur in a lipid bilayer environment.