Brown Group HomePage Publications Curriculum Vitae Send eMail Telephone: (520) 621-2163 FAX: (520) 621-8407 mfbrown@u.arizona.edu

Both experimental and theoretical nuclear magnetic resonance (NMR) methods are employed to gain new insights into the properties of liquid crystals, phospholipid bilayers, and biological macromolecules. We are also using fast photochemical methods to study the molecular basis of visual excitation in rhodopsin-containing membranes. Our research is multidisciplinary and provides opportunities for training in analytical techniques including NMR and optical spectroscopies; instrumentation development; biochemical methods including protein and lipid chemistry; and biotechnology.

I. NMR Spectroscopy of Liquid Crystals and Lipid Bilayers

Nuclear magnetic resonance spectroscopy is a powerful and unique tool for the study of matter in its various states, including solids, liquids, liquid crystals, and biological materials. Both structural and dynamic information can be obtained. We are presently employing deuterium NMR methods to obtain new knowledge regarding the dynamics and configurational properties of the molecular constituents of liquid crystals and phospholipid membranes. A variety of one- and two- dimensional NMR experiments are carried out. Here the spectral lineshapes yield information on the average molecular conformation, whereas analysis of the corresponding NMR relaxation times affords insight into the molecular dynamics.

II. Structure and Dynamics of Proteins

We are also extending and applying the above approaches to proteins to obtain information on their molecular dynamics over a wide range of time scales. Through application of modern NMR relaxation methods, one can understand how protein structural and dynamical properties are related to chemical reactivity and biological function.

III. Solid-State NMR Spectroscopy of Biological Macromolecules

Solid-state deuterium NMR spectroscopy is used to study bacteriorhodopsin, a membrane protein involved in solar energy conversion. In addition, we are engaged in applying solid-state NMR approaches to DNA, which provides a basis for investigations of protein-nucleic acid interactions.

IV. Lipid-Protein Interactions in Membranes

Our work in this area primarily involves NMR studies of the interactions of phospholipids with membrane proteins, including rhodopsin, the visual pigment. We are presently investigating influences of the bilayer thickness, degree of polyunsaturation, and incorporation of cholesterol and proteins on the properties of phospholipids in membranes.

V. Molecular Basis of Vision Studied by Fast Photochemical Reaction Techniques

This aspect of our work involves elucidation of the role of membranes in the visual process. To complement the above NMR studies, we are investigating lipid influences on the photochemistry of rhodopsin in artificial recombinant membranes. Rapid kinetic spectrophotometry in real time is employed, together with appropriate kinetic and thermodynamic modeling of the results.

Selected Publications

Brown, M.F. (1994), Modulation of Rhodopsin Function by Properties of the Membrane Bilayer, Chem. Phys. Lipids 73, 159-180.

Brown, M.F., and Chan, S.I. (1995), Bilayer Membranes: Deuterium & Carbon-13 NMR, in Encyclopedia of Nuclear Magnetic Resonance (Grant, D.M., and Harris, R. K., Eds.), Wiley, New York, pp. 871-885.

Brown, M.F. (1996), Membrane Structure and Dynamics Investigated with NMR Spectroscopy, in Membrane Structure and Dynamics (Merz, K.M., and Roux, B., Eds.), Birkhäuser, Boston, pp. 175-252.

Salamon, Z., Wang, Y., Soulages, J.L., Brown, M.F., and Tollin, G. (1996), Surface Plasmon Resonance Spectroscopy Studies of Membrane Proteins: Transducin Binding and Activation by Rhodopsin Monitored in Thin Membrane Films, Biophys. J. 71, 283-294.

Job, C., Zajicek, J., and Brown, M.F. (1996), Fast Field Cycling Nuclear Magnetic Resonance Spectrometer, Rev. Sci. Instr. 67, 2113-2122.

Nevzorov, A.A., Trouard, T.P., and Brown, M.F. (1997), Correlation Functions for Lipid Membrane Fluctuations Obtained from NMR Spectroscopy, Phys. Rev. E 55, 3276-3282.

Nevzorov, A.A., and Brown, M.F. (1997), Dynamics of Lipid Bilayers from Comparative Analysis of ¹³C and ²H NMR Relaxation Data as a Function of Frequency and Temperature, J. Chem. Phys., in press.

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