Random Phase Detection for Acceleration of Biomolecular NMR Experiments High resolution NMR spectroscopy is a powerful tool for investigating biomolecular systems under solution conditions comparable to those encountered in the cell or blood. It is the only method capable of determining 3-dimensional structure in solution with atomic resolution. It also can be applied to highly dynamic or intrinsically disordered biomolecules that cannot be studied by x-ray crystallography. It is uniquely capable of determining both the extent and rate of structural fluctuations in solution, and there is a growing appreciation that understanding protein dynamics is essential for understanding their biological functions. It also a powerful method for probing biomolecular interactions, and has important applications in drug discovery. Although remarkable advances in technology have enabled the application of NMR to increasingly complex biomolecular systems, the full potential resolution afforded by high field magnets is generally not achieved along all the dimensions of multidimensional experiments due to practical limits on measuring time. By employing non- Fourier methods of spectrum analysis that do not require data to be sampled at uniform intervals, it is becoming possible to achieve much higher resolution in multidimensional NMR experiments using practical amounts of measuring time. A factor limiting the ability to shorten NMR experiments is the need to determine the sign of the frequency of signal components. Conventional approaches to determining the sign impose a factor of two sampling burden. We recently discovered that an approach in which the phase of the detected signal is randomly varied (random phase detection) enables determination of the sign of the frequency without imposing a factor of two sampling burden.
The aim of this proposal is to explore the gains that can be achieved in reducing experiment time and/or improving resolution in multidimensional NMR experiments on biomolecules by combining nonuniform sampling in time with random phase detection. Further reductions in the time required to conduct multidimensional NMR experiments on biomolecules will render highly- dimensional experiments practical and extend applicability to systems that are fleetingly stable. Importantly, they will enable the full potentil resolution afforded by high-field magnets to be realized in the indirect dimensions of multidimensional experiments, extending the size and complexity of systems amenable to NMR investigation. Conversely, the reduced sampling requirements can be used to increase the sensitivity of multidimensional NMR, helping to facilitate the investigation of sparingly soluble o poorly abundant biomolecules.

Public Health Relevance

Random Phase Detection for Acceleration of Biomolecular NMR Experiments Multidimensional NMR spectroscopy is a uniquely powerful tool for investigating biological molecules, including their structure, dynamics, and interactions. Conventional methods face practical limits on measuring time, which limits the achievable resolution and in turn limits the complexity of the biomolecular systems that can be investigated. The methods to be developed in this project will permit high resolution spectra to be obtained in practical amounts of measuring time, helping extend the size and complexity of biomolecular systems that can be investigated to systems with greater biomedical relevance, thereby enabling both new discoveries and biomedical applications.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Exploratory/Developmental Grants (R21)
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Enabling Bioanalytical and Imaging Technologies Study Section (EBIT)
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Wehrle, Janna P
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University of Connecticut
Schools of Medicine
United States
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Hoch, Jeffrey C (2017) Beyond Fourier. J Magn Reson 283:117-123
Schuyler, Adam D; Maciejewski, Mark W; Stern, Alan S et al. (2015) Nonuniform sampling of hypercomplex multidimensional NMR experiments: Dimensionality, quadrature phase and randomization. J Magn Reson 254:121-30
Hoch, Jeffrey C; Maciejewski, Mark W; Mobli, Mehdi et al. (2014) Nonuniform sampling and maximum entropy reconstruction in multidimensional NMR. Acc Chem Res 47:708-17
Mobli, Mehdi; Hoch, Jeffrey C (2014) Nonuniform sampling and non-Fourier signal processing methods in multidimensional NMR. Prog Nucl Magn Reson Spectrosc 83:21-41
Schuyler, Adam D; Maciejewski, Mark W; Stern, Alan S et al. (2013) Formalism for hypercomplex multidimensional NMR employing partial-component subsampling. J Magn Reson 227:20-4