Robert Bryant

Robert G. Bryant

Nuclear Magnetic Resonance in Chemistry

The Bryant laboratory utilizes a wide range of nuclear and electron spin resonance methods to characterize intra and intermolecular dynamics. A primary focus is the rich information available from the study of the magnetic field dependence of the nuclear spin-lattice relaxation rate as a function of the magnetic field strength or what is called the magnetic relaxation dispersion (MRD). We have constructed unique instrumentation that permits acquisition of MRD profiles for a variety of nuclear resonances in high resolution. These measurements provide a direct measure of the time fluctuations in various nuclear or nuclear-electron dipolar couplings. The effective observe frequency for the magnetic noise is swept over many decades by changing the value of the magnetic field strength where the spins relax. Sensitivity is maintained by observing at a constant and high magnetic field. The resulting MRD profile reports relative inter and intramolecular motions over the time range from about ten microseconds to one picosecond. We are developing methods for probing the fluctuation spectrum of specific vectors defined in structurally interesting proteins and are trying to understand how these fluctuations affect molecular function. In related work, we apply the nuclear spin relaxation induced by freely diffusing paramagnetic solutes in cosolutes to define how one molecule samples the local environment of another and explores the surface or even penetrates into a complex structure like a folded protein. The measurements are sensitive to relatively weak intermolecular interactions and permit definition of highly localized intermolecular free energy differences in solutions.

A new field cycling NMR spectrometer that is low resolution but switches the magnetic field very rapidly permits accumulation of MRD profiles for systems that have been previously inaccessible. Multinuclear studies of proteins in a number of dynamical environments provide a fundamental characterization of how the protein structure fluctuates in time and how energy is redistributed in the folded structure. The practical implications range from understanding protein catalytic function to developing new techniques for diagnostic medicine in the context of magnetic resonance imaging or MRI.

Representative Recent Publications

Nuclear magnetic resonance and spin relaxation in biological systems. R. G. Bryant and J. P. Korb, Magn. Reson. Imaging, 23, 167-173 (2005).

Noise and Functional Protein Dynamics. J.-P. Korb, R. G. Bryant, Biophysical Journal, in press (2005).

Oxygen Accessibility to Ribonuclease A: Quantitative Interpretation of Nuclear Spin Relaxation Induced by a Freely Diffusing Paramagnet, C.-L. Teng, R. G. Bryant, J. Phys. Chem., in press (2005).

Chromium(III) Complexes as Intermolecular Probes. G. Diakova, Z. Fuller, K. Victor, K. Fumino, R. G. Bryant, J. Magn. Reson. 175, 65-72 (2005).

Magnetic Relaxation in Microporous and Dynamically Heterogeneous Materials, R. G. Bryant, J.-P. Korb, Adv. Inorg. Chem. 57, 293-326 (2005).

Mapping Oxygen Accessibility to Ribonuclease A Using High Resolution NMR Relaxation Spectroscopy. II. C.-L. Teng, R. G. Bryant, Biophys. J. (2004) 86, 1713-1725.

Magnetic Relaxation Dispersion of Lithium Ion in Solutions of DNA, K. G. Victor, C.-L. Teng, T. R. D. Dinesen, J.-P. Korb, R. G. Bryant, Magn. Reson. in Chem., 42, 518-523 (2004).

Magnetic Field Dependence of Proton Spin-lattice Relaxation of Confined Proteins. J.-P. Korb, R. G. Bryant, C. R. Physique 5 (2004) 349-359.

Magnetic Relaxation Dispersion Probe, K. Victor, V. Kavolius, R. G. Bryant, J. Magn. Reson., 171, 253-257 (2004).

High frequency dynamics in hemoglobin measured by magnetic relaxation dispersion. K. Victor, A. Van-Quynh, R. G. Bryant, Biophys. J. 88:443-454 (2004).

Local measures of intermolecular free energies in solution. C.-L. Teng S. Martini, R. G. Bryant, J. Amer. Chem. Soc., 126, 15253-15257 (2004).

Protein Reorientation and Bound Water Molecules Measured by 1H Magnetic Spin-Lattice Relaxation. A. Van-Quynh, S. Willson, R. G. Bryant, Biophysical Journal, 84, 558-563 (2003).

End-to-End Correlation for a C-12 Hydrocarbon Chain, S. Wagner, A. A. Nevzorov, J. H. Freed, R. G. Bryant, J. Magn. Reson. 160, 161-165(2003).

The Magnetic Field Dependence of T 1. J.-P. Korb, R. G. Bryant, Magn. Reson. Med. 48, 21-26 (2002).

O2 Penetration and Proton Burial Depth in Proteins: Applicability to Fold Family Recognition. G. Hernandez, C.-L. Teng, R. G. Bryant, and D. M. LeMaster. J. Am. Chem. Soc. 124, 4463-72 (2002).

Experiments with Tris(ethylenediamine)cobalt(III) compounds: 59Co NMR and the resolution of enantiomeric [Co(en)3]3+ Ion by Formatin of diasteriomeric ion pairs. L. L. Boren, J. G. Russell, R. E. Settlege, R. G. Bryant, J. Chem. Educ. 79, 494-8 (2002).

Proton Spin-Relaxation Induced by Localized Spin Dynamical Coupling in Proteins. J. P. Korb, A. Van Quynh, R. G. Bryant, Chem. Phys. Lett. 339, 77-82 (2001).

Experimental Characterization of Intermolecular Multiple Quantum Coherence Pumping Efficiency in Solution NMR. H. Zhang, N. Lizitsa, R. G. Bryant, W. Warren, J. Mag. Reson., 148, 200-208 (2001).

Molecular Oxygen Spin-Lattice Relaxation in Solutions Measured by Proton Magnetic Relaxation Dispersion. C.-L. Teng, H. Hong, S. Kiihne, R. G. Bryant, J. Magn. Reson. 148, 31-34 (2001).

Surface Nuclear Magnetic Relaxation and Dynamics of Water and Oil in Macroporous Media, S. Godfroy, J.-P. Korb, R. G. Bryant, Phys. Rev. E. 64, 21605 1-13pp (2001).

New Ways of Probing Surface Nuclear Relaxation and Microdynamics of Water and Oil in Porous Media. S. Godfroy, J.P. Korb, M. Fleury, R. G. Bryant, Magnetic Resonance Imaging 18, 517-519 (2001).

The Physical Basis for the Magnetic Field Dependence of Proton Spin-Lattice Relaxation Rates in Proteins and Tissues. J.-P Korb, R. G. Bryant, J. Chem. Phys. 115, 10964-10974 (2001).

Experimental Measurement of Nonuniform Dioxygen Accessibility to Ribonuclease A Surface and Interior. C.-L. Teng, R. G. Bryant, J. Am. Chem. Soc. 122, 2667-2668 (2000).