Figure 5
From: Ligand entry in human ileal bile acid-binding protein is mediated by histidine protonation
Backbone amide chemical shift differences for apo human I-BABP between pH = 5.9 and 7.0 (top left). Combined (1HN, 15N) chemical shifts were calculated using the equation of Δδ1HN, 15N =√[(ΔδHN)2 + (w1*ΔδN)2], where w1 (=0.154) is a weight factor determined using the BioMagResBank chemical shift database61. The dashed line corresponds to the mean value. Residues with substantially above average (mean + 0.5 SD and mean + SD in light and dark pink, respectively) are mapped on the ribbon diagram of hI-BABP (PDB entry 1O1U56). The position of the histidines is indicated in a ball-and-stick representation. The effect of ligand binding on pH-induced chemical shift changes is depicted at the bottom.
