Phosphorus-31 transverse relaxation rate measurements by NMR spectroscopy: Insight into conformational exchange along the nucleic acid backbone

Phosphorus (P-31) NMR spectroscopy can provide important information about the dynamics of nucleic acids. In this communication, we propose an inversely detected P-31 transverse relaxation rate (R-2) measurement experiment. This experiment enables fast measurement of accurate P-31 transverse relaxation rates and provides the possibility to detect slow motions mapped by the phosphorus nuclei along the nucleic acid backbone. Dispersion Curves show some P-31 nuclei experiencing chemical exchange in the millisecond time scale. Under the assumption of a two-state exchange process, the reduced lifetimes of the exchanging sites (tau(ex)) obtained are in accordance with base pair lifetime estimates deduced from imino proton exchange measurements.