EPR-based Distance Measurements in Oligonucleotides

The important role of DNA in biology has been known for a long time, but during the last decade it has become apparent that also RNA has many more functions than previously believed, ranging from gene regulation to catalysis of the polypeptide bond formation in the ribosomes. Thus, biophysical methods are needed that will allow the unravelling of their structures and conformational changes as well as dynamics and complex formations. Advances in site-directed spin labelling (SDSL) of oligonucleotides and electron paramagnetic resonance (EPR) spectroscopic methods like pulsed electron–electron double resonance (PELDOR or synonymously know as DEER) offer a means to achieve this and have been applied to various oligonucleotide systems. This chapter will give an overview of recent developments and applications in this field