Figure 3
From: Mapping the electrostatic potential of the nucleosome acidic patch
Glu residues in H2A have pKa below 5. (a) The 13C-H constant time HSQC spectrum of H2A shows pairs of peaks for each of the 7 Glu residues. (b) The HCCO spectrum showing Glu side chain carboxyl chemical shifts heavily overlap with each other. Dashed lines indicate the correlation to the 7 Glu signal pairs in the 13C-H HSQC. Peaks marked with the question mark could not be tracked in all pH conditions. (c) Overlay of the Glu region of HCCO spectra at indicated pH. Clear upfield chemical shift changes occur when pH drops below 5. (d) Chemical shift perturbation (CSP) curves with fits to the Henderson-Hasselbalch equation for H2A E120, E(1) and E(2), best-fit pKa value and standard deviation shown, numbers in brackets indicate the 95% confidence interval. E(1) and E(2) have the highest and lowest pKa value among the Glu signals, respectively.
