Seminar by Dr. Vipin Agarwal, TIFR Centre for Interdisciplinary Sciences (TCIS), TIFR Hyderabad on "Novel solid-state NMR methods for protein structure determination of crystalline and non-crystalline solids at nanomolar concentrations"
08 Aug 2019
Seminar Room #350
Talk Title : "Novel solid-state NMR methods for protein structure determination of crystalline and non-crystalline solids at nanomolar concentrations"
Abstract
Solid-state Nuclear Magnetic Resonanceis a powerful technique to provide structural insights into samples that are fundamentally non-crystalline or insoluble. In particular, the field of amyloid structural biology and recently, supramolecular assembly structures have benefited from this approach.1The current solid-state NMR structural approaches requirelarge quantities (~5-20milligrams) of 13C,15Nlabelled or (< 1mg) of 2H,13C,15Nlabelled protein samples for experiments.2,3This has limited the technique to systems that can be artificially enriched in large quantitates, in vitro. Very fast magic angle spinning (MAS) combined with high-magnetic fields and proton detection opens up avenues for high-resolution proton spectrum of fully protonated biomolecules.4The enhanced resolution only provides access to the important chemical properties of the protons. However, the real strength of proton NMR is in deciphering spatial proximity of protons,as they provide a direct means to structure of molecules and also an understanding of interactions that induce inter-molecular packing.However, thecurrentexperimental methods haveprovedchallenging inobtainingmeaningful distance restraints that are critical for NMR structural approaches. In this presentation, we discussnovelproton-protonrecouplingmethods developed for structural characterization of molecules in fully protonated molecules at fast MAS (above 60kHz).5The technique provides the flexibility to project out selective 1H-1Hcontacts up to distances of about 5-6 Åfrom a strongly coupled proton bath.The selectivity ensures a boost in sensitivity and that majority of the trivial 1H-1H contacts (intraresidue) are eliminated. A large set of these observed restraintsform the basis of NMR structurecalculation. We also introduce another methods, called SERPto measure quantitative1H-1Hdistancesin fully protonated molecules.6Thesenewapproachesprovide an opportunity forde-novosolid-state NMR 3D-structure determination with sample concentrations on the order of ~50 nanomoles.