During the late 1970’s and early 1980’s we recorded 2H and 31P spectra of static samples of lipid bilayer membranes to study the structure and dynamics of membrane lipids. However, the lack of resolution stimulated us to develop magic angle spinning (MAS) experiments, and we published our first paper in 1978 describing spectra of unsonicated lipid bilayers. As MAS technology developed, we initiated 1D experiments on specifically 13C and 15N labeled bacteriorhodopsin (bR) studying the structure of retinal and bR’s mechanism of H+ translocation. Two of the outstanding results were to establish that the Schiff linkage is protonated in bR and that the retinal was 6-s-trans, adding another double bond to the polyene chain and explaining its red shift from 500 nm in rhodopsin to 568 nm in bR. In addition, the bR experiments stimulated us to develop low temperature (80-200 K) trapping techniques so that we could examine the structure of photocycle intermediates and study the mechanism of H+/OH- pumping. This lead eventually to multidimensional 13C-15N experiments using DNP at low temperature to determine the structure of the important L and M intermediates. We are now pursuing similar experiments on other membrane proteins. In 2015 we published a high resolution structure of M218-60 and our studies of the voltage dependent anion channel (VDAC) are ongoing.
- V. S. Bajaj, M. L. Mak-Jurkauskas, M. Belenky, J. Herzfeld, and R. G. Griffin, “Functional and shunt states of bacteriorhodopsin resolved by 250-GHz dynamic nuclear polarization–enhanced solid-state NMR,” Proc. Nat’l. Acad. Sci. 106, 9244-49 (2009). DOI: 10.1073/pnas.0900908106; PMCID: PMC2695048
- M.T. Eddy, L. Andreas, O. Teijido, L. Clark, S.Y. Noskov, S.M. Bezrukov, G. Wagner, T.K. Rostovtseva, and R.G. Griffin, “Magic Angle Spinning Nuclear Magnetic Resonance Characterization of Voltage-Dependent Anion Channel Gating in Two-Dimensional Lipid Crystalline Bilayers” Biochemistry 54, 994-1005 (2015) DOI:10.1021/bi501260r PMCID: PMC4318587
- L.B. Andreas, M. Reese, M.T. Eddy, V. Gelev, Q.Z. Ni, E. A. Miller, L. Emsley, G. Pintacuda, J. J. Chou, R. G. Griffin, “Structure and Mechanism of the Influenza-A M218-60 Dimer of Dimers” J. Am. Chem. Soc. 137, 14877-14886(2015) DOI: 10.1021/jacs.5b04802; PMCID: PMC4943461
- Q.Z. Ni, T.V. Can, E. Daviso, M. Belenky, R.G. Griffin, J. Herzfeld, “Primary Transfer Step in the Light-Driven Ion Pump Bacteriorhodopsin: An Irreversible U-Turn Revealed by Dynamic Nuclear Polarization-Enhanced Magic Angle Spinning NMR.” J. Am. Chem. Soc.140, 4085-4091(2018); DOI: 10.1021/jacs.8b00022; PMCID: TBD