A Quad-Fast-MAS probe for Dramatically Improved Biomolecular Structure Determinations

DESCRIPTION provided by applicant A Quad Fast MAS probe for Dramatically Improved Biomolecular Structure Determinations Abstract The last years have seen steady progress in applying magic angle spinning MAS NMR to an increasingly wide range of applications in structural biology However the methods are all far from routine and often require mg of a concentrated sample that is extremely difficult to isolate and prepare suitably The andquot Holy Grailandquot i solids NMR would be the ability to successfully utilize the powerful suite of NMR acquisition and automated structure determination protocols developed for solution NMR which rely mostly on H detected triple and quad resonance schemes as such generally permit or times higher S N than direct detection for C and N respectively with solid samples of mg Four channel multinuclear probes with gradients have been the workhorse in solution NMR for decades but quad resonance solids probes have not been available they have been perceived to be impractically difficult to design and build This proposal seeks funding to develop build and test a prototype H X Y Z HR fast MAS probe based on a novel andquot single coilandquot rf circuit optimized for H detection and suitable for use at fields from T and rotor diameters from mm The Phase II probe will be compatible with automated sample exchange pulsed field gradients PFG and sample temperatures from K to K Moreover it will be essentially devoid of background signals for all the primary nuclides H P C H N and O Order of magnitude improvements in spectral resolution have been demonstrated for H detected methods in solids from the combination of improved sample perdeuteration optimal protonation of exchangeable sites faster spinning and higher polarizing fields seeing typical H linewidths in rigid proteins decrease from ppm to ppm Analysis suggests that a substantial portion of the remaining broadening is from J couplings to the deuterons which is not averaged by MAS and spinner dependent effects thermal gradients axial vibration and magnetism Calculations suggest H J couplings contribute Hz to H line broadening and available data suggest the probe limited resolution in commercially available fast MAS probes has contributed another Hz A channel HR MAS probe that permits simultaneous decoupling of C H and N achieves andgt kHz MAS rotation with order of magnitude lower thermal gradients and is capable of Hz resolution on liquids H resolution is expected to enable H linewidths below ppm on most of the residues in rigid proteins at MHz and above The novel circuit will also be tunable to virtually all combinations of interest such as H C H N H P C H H P Li C H Al Si O and H C Si Rh thereby making it also invaluable in such areas as metabolism neurology materials science catalysis and sustainable energy PUBLIC HEALTH RELEVANCE A Quad Fast MAS probe for Dramatically Improved Biomolecular Structure Determinations Narrative Thousands of researchers are regularly using Nuclear Magnetic Resonance NMR techniques with a majority of the applications driven by the need for structure and function determination in biological macromolecules The advances developed under this project will allow every NMR laboratory that has a wide bore magnet to apply their liquids methods to solids on a budget they will be able to afford equipping biomedical researchers with superb new tools for the structure function studies of membrane proteins cellular membrane systems and numerous other areas