2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

Abstract

Perdeuteration of biological macromolecules for magic angle spinning solid-state NMR spectroscopy can yield high-resolution 2H–13C correlation spectra and the method is therefore of great interest for the structural biology community. Here we demonstrate that the combination of sample deuteration and dynamic nuclear polarization yields resolved 2H–13C correlation spectra with a signal enhancement of ε ≥ 700 compared to a spectrum recorded with microwaves off and otherwise identical conditions. To our knowledge, this is the first time that 2H-DNP has been employed to enhance MAS-NMR spectra of a biologically relevant system. The DNP process is studied using several polarizing agents and the technique is applied to obtain 2H–13C correlation spectra of U-[2H, 13C] proline.

Solvent-Free High-Field Dynamic Nuclear Polarization of Mesoporous Silica Functionalized with TEMPO

“…Furthermore, direct 29 Si DNP yields DNP enhancements, e DNP ð 29 SiÞ ¼ 2:6 and e A DNP ð 29 SiÞ ¼ 3; which are more than 50 % higher than those measured for direct 1 H DNP. The higher signal enhancements in direct 29 Si DNP compared to direct 1 H DNP are consistent with the theoretical maximal enhancements [17,68,69], which are given by the ratios c e /c( 29 Si)& 3311 for 29 Si and c e /c( 1 H)& 658 for [17]. The lower e DNP ð 29 SiÞ values for 1 stem from different factors.…”

“…First, the polarization transfer in 1 relies mainly on mono-radical TEMPO, whereas the biradicals, such as TOTAPOL, are usually more efficient at high field [21,[54][55][56]. Second, in this work, DNP experiments were performed at a B 0 value, which is optimal for direct 1 H DNP employing nitroxide radicals but not optimal for the direct polarization of isotopes with low gyromagnetic ratios [17,68,69]. Third, as explained above for 1 H DNP, the electron and nuclear relaxations must be faster in 1 than in mesoporous silica impregnated with frozen solutions.…”

Structural Insights into Bound Water in Crystalline Amino Acids: Experimental and Theoretical 17O NMR

“…, inhibiting motional averaging) our experimental results (as well as Rees et al ) were collected at room temperature, where partial averaging could occur. While oxygen dynamics could affect the observed quadrupolar couplings, 90 with previous studies 23–26,92,93 indicating small effects on both the lineshape and magnitude of the quadrupolar coupling interaction, closer examination of our chemical environments shows that the symmetry of the water itself restricts dynamics in any direction that would reduce the V zz component. The medium-range structure ( i.e.…”

Dynamic Nuclear Polarization in Solids: The Birth and Development of the Many-Particle Concept

“…Under the opposite conditions, a narrow hole is burned in the EPR line by the resonant saturation, and the 3-spin ENCE can be the most effective DNP mechanism. The situation may be illustrated by the comparison of the DNP experiments performed at 90 K and 5 T on different nuclei [50,51]: an asymmetric E(D p ) curve typical of the ENCE mechanism ( 1 H) is changed for antisymmetric one consistent with Eq. (4) for lower NMR frequencies ( 13 C, 2 H) and narrow EPR line.…”