The Effects of Dissolved Oxygen upon Amide Proton Relaxation and Chemical Shift in a Perdeuterated Protein

Molecular oxygen as a paramagnetic NMR probe of protein solvent exposure and topology

“…Moreover, one need not be concerned with deuteration levels and the effects of spin-diffusion in the case of these paramagnetic shifts. Modest oxygen-induced 1 H chemical shift perturbations have been previously reported in protein studies (12), and 19 F chemical shift perturbations as high as 4.0 ppm at 100 bar oxygen partial pressures have been observed and subsequently used to study membrane immersion depth (13) and protein solvent exposure (14). Measurable 13 C paramagnetic shifts (roughly 0.4 ppm or less) at oxygen partial pressures of 30 and 60 bar were also reported and interpreted in terms of protein structure and solvent exposure.…”

“…Thus, R 1p is acutely sensitive to local topology (i.e., f and b above). Note that since the paramagnetic rates depend on the square of the gyromagnetic ratio, relatively large (relaxation) effects may be seen on 1 H and 19 F nuclei (8,11,12,(18)(19)(20) …”

Transient NOE-exchange-relay experiment: Application to ligand–protein binding under slow exchange conditions

“…Proton-proton dipolar and proton CSA interactions were taken into consideration in calculating the relaxation matrix elements. In addition, a small contribution from paramagnetic O 2 into the autorelaxation rates, 0.05 s À1 , was included [30]. The proton CSA tensor was assumed to be axially symmetric with unique axis along the CH bond and the anisotropy of 10 ppm [31].…”

An NMR study of the origin of dioxygen-induced spin-lattice relaxation enhancement and chemical shift perturbation

“…In particular, we report on the use of 19 F and 13 C NMR to assess the mechanism of spin-lattice relaxation enhancement and chemical shift perturbation by oxygen, using a small semiperfluorinated probe molecule, CF 3 (CF 2 ) 5 C 2 H 4 -Omaltose (TFOM) in a membrane model system. Although oxygen has been used effectively in a variety of NMR studies involving water soluble proteins [9][10][11], it has several unique attributes as a paramagnetic probe in NMR studies of membranes:…”