Methodology and Applications of High Resolution Solid- State Nmr to Structure Determination of Proteins

A number of methodological developments and applications of solid-state NMR for assignment and high resolution structure determination of microcrystalline proteins and amyloid fibrils are presented. Magic angle spinning spectroscopy on uniformly and selectively C and N labeled samples is performed at magnetic fields from 11.7 to 21.1 T and spinning frequencies from 9 to 65 kHz. Dynamic Nuclear Polarization on nanocrystals of amyloidogenic peptide GNNQQNY is presented demonstrating that H-H spin diffusion can efficiently transfer the enhanced polarization across the solute that is not in an intimate contact with the polarizing agent. An improved theoretical treatment of Rotational Resonance Width (RW) experiments and its application to determination of precise C-C distance is presented. A general theory of second averaging in modulation frame for designing solid-state NMR experiments is introduced and discussed in the context of two methods: Cosine Modulated Rotary Resonance (CMpRR) for performing a broadband double-quantum C-C recoupling without the need for additional H decoupling and Cosine Modulated recoupling with Chemical Shift reintroduction (COMICS) that provides a general frequency selective method for measuring precise C-C distances in uniformly labeled solids. Cosine Modulated Adiabatic Recoupling (CMAR) – an adiabatic extension of the CMpRR, that is particularly robust with respect to rf inhomogeneity, is also introduced. A number of applications CMpRR at 21.1 T to proteins with varying degrees of macroscopic order are presented. A second order Third Spin Assisted Recoupling (TSAR) mechanism is introduced and discussed in detail. The heteronuclear TSAR – Proton Assisted Insensitive Nuclei Cross-Polarization (PAIN-CP) and homonuclear Proton Assisted Recoupling (PAR) yield long distance C-N, C-C and N-N restraints in uniformly labeled systems with spinning frequencies up to 65 kHz that are used for protein structure calculation. Structure, dynamics and polymorphism of amyloidogenic peptide GNNQQNY from the yeast protein sup35p are investigated. Finally, PAIN-CP and C-C PAR are used for high resolution de novo structure determination of 10.4 kDa Crh protein dimer. Thesis supervisor; Robert Guy Griffin Title: Professor of Chemistry, Director of Francis Bitter Magnet Laboratory