Pulsed Third-Spin-Assisted Recoupling NMR for Obtaining Long-Range 13C–13C and 15N–13C Distance Restraints
Year: 2020
Type: article
Abstract: We introduce a class of pulsed third-spin-assisted recoupling (P-TSAR) magic-angle-spinning (MAS) solid-state NMR techniques that achieve efficient polarization transfer over long distances to provide important restraints for structure determination. These experiments operate with the same principle as continuous-wave (CW) TSAR experiments, by utilizing second-order cross terms between strong 1 H- 13 C and 1 H- 15 N dipolar couplings to achieve 13 C- 13 C and 13 C- 15 N polarization transfer. However, in contrast to the CW-TSAR experiments, these pulsed P-TSAR experiments require much less radiofrequency (rf) energy and allow a much simpler routine for optimizing the rf field strength. We call the techniques PULSAR (PULSed proton Asissted Recoupling) for homonuclear spin pairs and PERSPIRATION CP (Proton-Enhanced Rotor-echo Short Pulse IRradiATION Cross-Polarization) for heteronuclear spin pairs. We demonstrate these techniques on the model protein GB1, and found cross peaks for distances as long as 10 and 8 Å for 13 C- 13 C and 15 N- 13 C spin pairs, respectively. We also apply these methods to the amyloid fibrils formed by the peptide hormone glucagon, and show that long-range correlation peaks are readily observed to constrain intermolecular packing in this cross-β fibril. We provide an analytical model for the PULSAR and PERSPIRATION CP experiments to explain the measured and simulated chemical shift dependence and pulse flip angle dependence of polarization transfer. These two techniques are useful for measuring long-range distance restraints to determine the three-dimensional structures of proteins and other biological macromolecules.
Institution: Massachusetts Institute of Technology
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Awards: New RF Electronics Console and Probes for 900 Mhz NMR Spectrometer, G3186096830, G3450364201, Structures and lipid interactions of curvature-inducing membrane peptides by NMR, G4524128745, Molecular structures of tau aggregates studied by solid-state NMR, MIT/Harvard Center for Magnetic Resonance, Solid-state NMR studies of the dynamic interactions of the influenza A M2 membrane protein with water, antiviral drugs, and the M1 protein, G9000202055, Tau structure and dynamics in Alzheimer's disease
OpenAlex ID: W3044092814