Michael F Brown
Professor, Applied Mathematics - GIDP
Professor, BIO5 Institute
Professor, Chemistry and Biochemistry-Sci
Primary Department
(520) 621-2163
Research Interest
Michael F. Brown is Professor of Chemistry & Biochemistry at the University of Arizona. He is co-director of the Biological Physics Program and the Chemical Physics Program, and was a co-founder of the Biological Chemistry Program at the University of Arizona. He is internationally renowned for his work on the molecular basis of activation of G-protein-coupled receptors that are the targets for the majority of pharmaceuticals and medicines used by humans. The focus of his work is on biomembranes, with a particular emphasis on lipid-protein interactions in relation to potential drug targets involving membrane proteins. He is involved with investigation of the molecular basis of visual signaling involving rhodopsin. Moreover, Professor Brown is an expert in nuclear magnetic resonance (NMR) spectroscopy. His activities in the area of biomolecular NMR spectroscopy involve the devolvement and application of methods for studying the structure and dynamics of biomolecules. Michael Brown has authored over 130 original research papers, 10 book chapters, 4 book reviews, and has published more than 275 abstracts. His current H-index is 43. He numbers among his coworkers various prominent scientists worldwide. He presents his work frequently at national and international conferences, and is the recipient of a number of major awards. Professor Brown's many contributions have established him as a major voice in the area of biomembrane research and biomolecular spectroscopy. He is frequently a member of various review panels and exerts an influence on science policy at the national level. Among his accolades, he is an elected Fellow of the American Association for the Advancement of Science; American Physical Society; Japan Society for the Promotion of Science; and the Biophysical Society. He is a Fellow of the Galileo Circle of the University of Arizona. Most recently, he received the Avanti Award of the Biophysical Society. This premier honor recognizes his vast and innovative contributions to the field of membrane biophysics, and groundbreaking work in the development of NMR techniques to characterize lipid structure and dynamics. Most recently he presented the 2014 Avanti lecture of the Biophysical Society.

Publications

Nevzorov, A. A., & Brown, M. F. (1997). Dynamics of lipid bilayers from comparative analysis of 2H and 13C nuclear magnetic resonance relaxation data as a function of frequency and temperature. The Journal of Chemical Physics, 107(23), 10288-10310.

Abstract:

Analysis of the nuclear spin relaxation rates of lipid membranes provides a powerful means of studying the dynamics of these important biological representatives of soft matter. Here, temperature- and frequency-dependent 2H and 13C nuclear magnetic resonance (NMR) relaxation rates for vesicles and multilamellar dispersions of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in the liquid-crystalline state have been fitted simultaneously to various dynamic models for different positions of the acyl chains. The data include 2H R1z rates (Zeeman order of electric quadrupolar interaction) acquired at 12 external magnetic field strengths from 0.382 to 14.6 T, corresponding to a frequency range from ωD/2π=2.50-95.3 MHz; and 2H R1Q rates (quadrupolar order of electric quadrupolar interaction) at 15.3, 46.1, and 76.8 MHz. Moreover, 13C R1z data (Zeeman order of magnetic dipolar interaction) for DMPC are included at six magnetic field strengths, ranging from 1.40 to 17.6 T, thereby enabling extension of the frequency range to effectively (ωC+ωH)/2π=938.7 MHz. Use of the generalized approach allows formulation of noncollective segmental and molecular diffusion models, as well as collective director fluctuation models, which were tested by fitting the 2H R1Z data at different frequencies and temperatures (30 °C and 50 °C). The corresponding 13C relaxation rates were predicted theoretically and compared to experiment, thus allowing one to unify the 13C and 2H NMR data for bilayer lipids in the fluid state. A further new aspect is that the spectral densities of motion have been explicitly calculated from the 2H R1Z and R1Q data at 40 °C. We conclude that the relaxation in fluid membrane bilayers is governed predominantly by relatively slow motions, which modulate the residual coupling remaining from faster local motions (order fluctuations). Only the molecular diffusion model, including an additional slow motional process, and the membrane deformation model describing three-dimensional collective fluctuations fit the 2H NMR data and predict the 13C NMR data in the MHz range. Orientational correlation functions have been calculated, which emphasizes the importance of NMR relaxation as a unique tool for investigating the dynamics of lipid bilayers and biological membranes. © 1997 American Institute of Physics.

Mertz, B., Ritter, E., Bartl, F., & Brown, M. F. (2012). Rhodopsin Activation is Modulated by Non-Specific Membrane Lipid-Protein Interactions. Biophysical Journal, 102, 468.
Feng, J., Mertz, B., & Brown, M. F. (2015). Retinal Flip in Rhodopsin Activation?. Biophysical Journal, 108, 2767-2770.
Brown, M. F. (1979). Deuterium relaxation and molecular dynamics in lipid bilayers. Journal of Magnetic Resonance (1969), 35(2), 203-215.

Abstract:

The quadrupolar relaxation of deuterium-labeled lipid bilayers has been analyzed using standard Redfield theory and is discussed with regard to the problem of chain segmental motion and order in membranes. Considering the segmental reorientation as a stochastic process, the T1 and T2 relaxation rates are interpreted in terms of the rate of motion, characterized by one or more correlation times τ2M, and statistical amplitude, characterized by the segmental order parameter SCD. For the case of phospholipid bilayers with |SCD| ≲ 0.2, the relaxation rates are predominantly determined by the rate of motion, rather than the ordering. Recently obtained T, relaxation data for selectively deuterated and perdeuterated multilamellar dispersions of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine are analyzed and compared to the results of previous carbon-13 T1 relaxation studies. The available experimental results suggest that the fast segmental motions affecting T1 in these systems can be treated to a reasonable degree of approximation in terms of a single effective correlation time. © 1979.

Trouard, T. P., Nevzorov, A. A., Alam, T. M., Job, C., Zajicek, J., & Brown, M. F. (1999). Influence of Cholesterol on Dynamics of Dimyristoylphosphatidylcholine Bilayers as Studied by Deuterium NMR Relaxation. The Journal of Chemical Physics, 110, 8802-8818.