The values of amide proton Δδ/ΔT were determined from the measured chemical shifts of backbone NH signals in the 1H−15N HSQC spectra over the temperature range 0 30°C with 5°C increment; linear variation of chemical shift with temperature was observed.
H,N-TROSY spectra were collected to monitor chemical shifts of backbone amides in R0RBR.
Usually, changes in side-chain positions are proportional to the magnitude of backbone shifts, with shifts larger than 4Å typically resulting in very large changes in side-chain positions as a result of reorientations of the Cα Cβ bond vectors.
Chemical shift assignments for backbone atoms can be converted to ϕ and ψ backbone angle restraints (33) and are used during the selection of the fragment libraries.
For example, for residue i of a target protein, a peak for N-HSQC at position (Ni, HNi) and a peak for HNCO at positions (Ni, HNi, Ci−1) are generated, where Ni, HNi and Ci−1 are experimentally assigned chemical shift values of backbone N and HN atoms for residues i, and a chemical shift value of the backbone C atom for residue i − 1, respectively.
At neap tides he felt England's backbone shift and shiver; saw the caverns fill, the railways rivered and the Pennine mackerel flashing through lead mines, the last dove lifting from the summit of Lose Hill.
This zinc binding is accompanied by a large shift in the backbone conformation of the 99-loop and by large movements of both His side-chains.
NMR chemical shift perturbations of backbone amides in Bcl-xL and reduced cytochrome c reveal that the two proteins form detectable amounts of an adduct.
On the C-terminal side of helix α2, where almost no backbone shift is seen, Tyr191 rotates 180 degrees around its χ1-angle (Fig. 4C).
Chemical shift assignments of backbone amides are indicated on the plot.
