Department of Chemistry

College of Science

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Current Activities

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Biological membranes provide the boundaries that define cells or cell compartments by delimiting them from the exterior. Their components, mainly membrane lipids and proteins, perform a variety of functions, ranging from providing structural stability to receiving and transmitting signals, and importing and exporting substances. Despite the central importance of membrane proteins, present knowledge of their structure and functional mechanisms at the atomic level is limited due to challenges in obtaining sufficiently concentrated samples for use with conventional experimental methods.

In order to gain insight into these questions, we employ recently developed techniques of nuclear magnetic resonance (NMR) spectroscopy in the solution state. NMR uniquely provides a means both for obtaining the three-dimensional molecular structure and for determining interactions and mechanisms. In particular, we are interested in elucidating the structural basis for mechanisms of membrane biogenesis and transport by studying proteins from the membrane insertion and translocation machinery of gram-negative bacteria and mitochondria. Important components of our work in this area are the expression, purification and reconstitution of membrane proteins, as well as the application and further development of NMR methodology.

Due to their biophysical properties, it is often difficult to obtain samples of membrane proteins that are of sufficient quality for typical NMR experiments. We aim to extend the applicability of NMR to study such systems by developing methods for the use of hyperpolarization, which can yield signal enhancements of up to 10,000 fold when compared to conventional NMR. Dynamic nuclear polarization (DNP) is a newly available technology to provide hyperpolarization of various classes of molecules, for example ligands that bind to membrane proteins. Even at low concentrations, specific processes involving DNP-polarized molecules may be observed both at equilibrium and transiently. This is of particular importance to investigate, for example, mechanisms of signaling, as well as to develop new applications for determining ligand binding in drug discovery.

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Selected Publications

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Hilty, C., Lowery, T.J., Wemmer, D.E. and Pines, A. Spectrally Resolved Magnetic Resonance Imaging of the Xenon Biosensor. Angew. Chem. Int. Ed. 45(1): 70-73 (2006).

Baker, K.A., Hilty, C., Peti, W., Prince, A., Pfaffinger, P.J., Wider, G., Wüthrich, K. and Choe, S. N-terminal inactivation of a voltage-gated K channel viewed by NMR in solution. Biochemistry 45(6): 1663-1672 (2006).

Lee, D., Hilty, C., Wider, G. and Wüthrich, K. Efficient Correlation Time Measurements for Macromolecules from NMR Relaxation Interference. J. Magn. Reson. 178: 72-76 (2006).

Hilty, C., McDonnell, E., Granwehr, J., Han, S.I., Pierce, K. and Pines, A. Microfluidic gas flow profiling using hyperpolarized xenon and remote detection. P. Natl. Acad. Sci. USA 102(42): 14960-14963 (2005).

Hilty, C., Wider, G., Fernández, C. and Wüthrich, K. Membrane protein-lipid interactions in mixed micelles studied by NMR spectroscopy with the use of paramagnetic reagents. ChemBioChem 5(4): 467-473 (2004).

Fernández, C., Hilty, C., Wider, G., Güntert, P. and Wüthrich, K. NMR structure of the integral membrane protein OmpX. J. Mol. Biol. 336(5): 1211-1221 (2003).

Hilty, C., Wider, G., Fernández, C. and Wüthrich, K. Stereospecific assignments of the isopropyl methyl groups of the membrane protein OmpX in DHPC micelles. J. Biomol. NMR 27(4): 377-382 (2003).

Fernández, C., Hilty, C., Wider, G. and Wüthrich, K. Lipid-protein interactions in DHPC micelles containing the integral membrane protein OmpX investigated by NMR spectroscopy. P. Natl. Acad. Sci. USA 99(21): 13533-13537 (2002).

Hilty, C., Fernández, C., Wider, G. and Wüthrich, K. Side chain NMR assignments in the membrane protein OmpX reconstituted in DHPC micelles. J. Biomol. NMR 23(4): 289-301 (2002).

Hilty, C. and Winterhalter, M. Facilitated substrate transport through membrane proteins. Phys. Rev. Lett. 86(24): 5624-5627 (2001).