Measuring Distances between Sites in Biomolecules by Electron Paramagnetic Resonance

Abstract

Interpretation of the function of biomolecules at the molecular level requires knowledge of the three-dimensional structure. Electron paramagnetic resonance methods can be used to determine the distance between paramagnetic sites that are intrinsic to a biomolecule or are added by attachment of stable nitroxyl radicals or paramagnetic metals. Techniques have been developed to measure distances ranging from about 5 to 70 Å (0.5 to 7.0 nm). This article provides an overview of techniques and examples of systems to which they have been applied.