Why NMR?: NMR spectroscopy can be used to measure dynamics at atomic resolution and to deduce structural, kinetics and thermodynamic characteristics of many motional modes occurring at different time scales. NMR spectroscopy has broad sensitivity to motions spanning picosecond to second and longer timescales and can be used to characterize very subtle changes in conformation, including those involving minutely populated conformers that have exceptionally short lifetimes (on the order of nanoseconds). Last but not least, NMR spectroscopy is a powerful approach for exploring how the dynamic structure landscape is modulated by cellular cues, and time-resolved methods can be used to follow these perturbations in real time. Click here for more details on studying dynamics by NMR.*
The basic NMR experiment can be simplistically described as follows: Nuclei behave as tiny magnets, and because of the quantization of the nuclear spin angular momentum, they align either parallel (α state) or antiparallel (β state) relative to the applied magnetic field. As the parallel (or antiparallel, depending on the nucleus) alignment is energetically more favorable, a net bulk magnetization over an ensemble of nuclei builds up parallel to the magnetic field. Radiofrequency pulses are then used to realign this bulk magnetization along a direction perpendicular to the magnetic field. The bulk magnetization then precesses about the magnetic field at a characteristic NMR frequency called the ‘chemical shift’ and gives rise to a detectable oscillating magnetic field. This non-equilibrium magnetization ultimately relaxes back to the equilibrium, parallel state. The time-domain spectrum is Fourier-transformed to yield the standard frequency-domain NMR spectrum, in which unique signals at characteristic chemi- cal shift frequencies are observed for different types of nuclei. For nucleic acid and protein applications, one is typically interested in the NMR-active nuclei 1H, 13C, 15N, 2H and 31P.*
*Reference: Nature Methods; 2011, 8(11), 919-931
Research in our lab is focussed on various aspects of solution NMR including theoretical design and experimental implementation of new NMR experiments to probe the biophysical characteristics of RNA and proteins; understanding functional aspects of non-coding RNAs; and structural biology of microRNAs and their regulation in various disease settings.