Membrane Investigation by Solid-State NMR

The atomic resolution insight provided by solid-state NMR is vital for expanding our understanding of membrane biology. Advances in protein structure determination using solid-state NMR data, coupled with proton detection using very fast magic-angle spinning rates in the solid state, have the lab extremely well positioned to tackle these problems. We do this with a combination of the highest quality NMR data and cutting-edge computational methods to determine the structure and dynamics of proteins and membranes.

We seek to study membrane proteins in their native lipids, and determine the effects the lipids bilayer itself has on the protein and understand why they occur via the direct investigation of membranes by solid-state NMR. To do this, we continue to develop techniques for directly probing the structure and dynamics of lipid bilayers by solid-state NMR as well as the effects that different lipid species and small molecules can have on them. At Rutgers we have improved the 31P spectroscopy used to directly observe lipid head-groups. We use very-fast MAS and proton detection to observe lipid-lipid and lipid-protein interactions. We are developing pulse sequences and data analysis workflows to measure precise lipid-protein distances using 1H, 13C, 15N and 31P. 

NMR Method Development

We seek to apply the power of 1H-detected ssNMR to growing numbers of areas in ssNMR. Due to the fact 1H’s gyromagnetic ratio is 4 times that of 13C, experiments detecting 1H are more sensitive and therefore faster. While 1H detection is increasing well developed in terms of chemical shift assignments, there is still a wide array of areas where it has not yet been deployed. In particular, we are interested on using ultrafast MAS with 1H detection to gain structural insight without deuterated samples. We are developing new pulse sequences to determine intermolecular distances both within a protein and intermolecularly, as well as study dynamics at many timescales. We have a MAS probe which can spin at 40 kHz and another which spins at 100 kHz is on the way.

In addition to 1H detected methods, we will use 31P detected methods. 31P is spin 1/2, 100% abundant, and relatively high gamma (17.235 MHz/T). It has good lineshape and sensetivity, a wide chemical shift range, and a large dipolar coupling range (~ 8 A). In addition, we expect to be able to filter out the lipid phosphate signal to obtain spectra with good signal-to-noise of specific phosphates we are interested in.