Deuterium Rotating Frame NMR Relaxation Measurements in the Solid State under Static Conditions for Quantification of Dynamics

Abstract

The feasibility of static deuterium rotating frame NMR relaxation measurements for characterization of slow timescale motions in powder systems is demonstrated. Using a model compound dimethyl sulfone-d , we show that these measurements yield conformational exchange rates and activation energy values in accordance with results obtained with other techniques. Furthermore, we demonstrate that the full Liouvillian approach as opposed to the Redfield approximation is necessary to analyze the experimental data.

Deuteron Solid‐State NMR Relaxation Measurements Reveal Two Distinct Conformational Exchange Processes in the Disordered N‐Terminal Domain of Amyloid‐β Fibrils

“…The following 16‐step phase cycle is used: φ 1 = x , y ,− x ,− y ; φ 2 = y , x , y , x ,− y ,− x ,− y ,− x ; φ 3 = y , x , y , x ,− y ,− x ,− y ,− x , − y ,− x ,− y ,− x , y , x , y , x ; φ rec =− x ,− y , x , y . B) Pulse sequence for static 2 H solid‐state R 1ρ measurements . The heat compensation block SL(max‐ T ) is followed by the inter‐scan delay d 1 and the preparation 90° pulse, followed by a variable spin‐lock delay SL( T ).…”

“…We checked that the full Liouvillian treatment renders negligible changes to the results. R 1ρ simulations for the H6 and G9 residues utilized the full Liouvillian treatment, as described in . The number of crystallites used was governed by the fraction of the bound state in each residue and corresponded to 90 for A2 and 250 for H6 and G9.…”

“…B) Pulse sequence for static 2 H solidstate R 11 measurements. [46] The heat compensation block SL(max-T) is followed by the inter-scan delay d 1 and the preparation 90°pulse, followed by a variable spin-lock delay SL(T). The detection is accomplished using the quadrupole echo scheme, τ À 90°À τ.…”

Deuteron Quadrupolar Chemical Exchange Saturation Transfer (Q‐CEST) Solid‐State NMR for Static Powder Samples: Approach and Applications to Amyloid‐β Fibrils

“…Experimental data ( Figure 6B) were obtained using the pulse sequence of Figure 1 at two temperatures: 68°C at which the flips are active and 10°C at which the flips are frozen out; we also used a saturation field of 1.3 kHz with a saturation time of 20 ms. [31] Figure 3 and Figure S1 also underline the comparative range of the sensitivity of timescales for Q-CEST as opposed to the quadrupolar echo line shape experiment. Thus, the flip motions have a negligible effect on the line shapes [26] and the spectra represent a nearly rigid pattern narrowed by a factor of one-third due to the fast methyl rotation.…”

“…[37] The temperature was set to 37°C. The RF field strength calibrations were performed as described in previous work utilizing the spin-lock-based method of the transverse component [31] and employing a D 2 O sample due to a weak RF field, which cannot lock wide powder patterns. The RF field strength calibrations were performed as described in previous work utilizing the spin-lock-based method of the transverse component [31] and employing a D 2 O sample due to a weak RF field, which cannot lock wide powder patterns.…”