Ni-DO2A structure. Schematic representation of Ni-DO2A, with DO2A2- shown as sticks, and Ni2+ as a grey ball. Carbons are in green, nitrogens in blue, oxygens in red. Hydrogens are not shown for the clarity sake.
Supplementary Figure 2
Effects of Ni-DO2A concentrations greater than 40 mM. Representative signal intensities of AS determined in 1D 1H-15N SOFAST-HMQC experiments plotted as a function of scan time (tscan), in the presence of 40 mM (red), 60 mM (brown) and 80 mM (turquoise blue) Ni-DO2A. A decrease in overall NMR signal intensity for Ni-DO2A concentrations larger than 40 mM is clearly visible.
Supplementary Figure 3
Effects of Ni-DO2A on residual water magnetization. Water longitudinal magnetization at the beginning of the acquisition periodwas measured and plotted as a function of tscan. This was achieved by the following scheme: a final 90 degree hard pulse was introduced after 128 scans of the 1H-15N SOFAST-HMQC pulse sequence, followed by the acquisition of the water signal.Experiments were performed in the presence of 0 mM (black), 10 mM (blue), 20 mM (purple) and 40 mM (red) Ni-DO2A.
Supplementary Figure 4
Effects of Ernst angle variations on NMR signal intensities. Representative signal-to-noise (S/N) curves of AS (top) in 1D 1H-15N SOFAST-HMQC NMR experiments in the absence of Ni-DO2A-, plotted as a function of scan time (tscan)-, obtained with first polychromatic pulse angles of 90 (black), 105 (yellow) and 120 (blue) degrees at 283K and 303K. Bottom curves represent data conversion to S/N per unit of experimental time plotted as a function of tscan. Highest measured signal intensities for the 90 degreepulse were set to 1. Intensities for the other data points were calculated with respect to this normalized value.
Supplementary Figure 5
Residue-resolved enhancement analysis for proton- and carbon-detected 2D NMR experiments. NMR signal enhancements in 2D 1H-15N SOFAST-HMQC NMR experiments on histone H3 (aa1-33) at 283K (a.) and 303K (b.) as determined by resonance cross-peak intensity measurements. Ni-DO2A concentrations were 10mM (blue), 20mM (purple) and 40mM (red). NMR signals in the absence of Ni-DO2A were set to 1. All other intensities were determined relative to this value. Data on the far right areNMR signal enhancements in 2D (H-flip)13CO/15N NMR experiments on H3 at 303K.
Supplementary Figure 6
Residue-type enhancements for proton- and carbon-detected 2D NMR experiments on AS. Based on their chemical exchange behavior, AS amino acids were grouped into two families. Residues experiencing fast NH-water exchange (fast exch) and those that displayed slow chemical exchange (slow exch). Average signal enhancements in the presence of 40mM Ni-DO2A are displayed for 2D 1H-15N SOFAST-HMQC (283K and 303K) and 2D (H-flip)13CO/15N (303K) experiments. Error bars denote variations in signal intensity enhancements of individual residue types (errors scale with the numbers of residues of one particular type in the protein).
Supplementary Figure 7
Signal response curves of SOFAST-HMQC and HSQC type experiments. Representative signal-to-noise per unit of experimental time curves were plotted as a function of tscan for 1H-15N HSQC (squares)1H-15N SOFAST-HMQC (circles), at 303 K and pH 6.4. Ni-DO2A concentrations were 0 mM (black) and 40 mM (red).