Nanometer distance measurements on RNA using PELDOR.

A rapid increase in RNA structural studies has been seen in the past few years, in part due to the interest in the multitude of cellular functions performed by RNA. Electron paramagnetic resonance spectroscopy is a useful technique for studying biopolymer structure under physiologically relevant conditions. We present herein the use of pulsed electron double resonance for the determination of a 35 +/- 2 A distance between two spin label nitroxides that were linked to specific positions within an RNA.