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![[Figure 2]](mn5110fig2mag.jpg)
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Figure 2
Protonation states of histidine residues in deoxyHb versus CNmetHb with pKa values determined by previous NMR and H/D-exchange studies, and by molecular mechanics calculations based on high-resolution crystal structures. The protonation states of His residues are indicated by their charge: `0' refers to a neutral His side chain (imidazole ring), while +1 indicates that the His side chain is protonated (formal positive charge). The position of the D atom is indicated by δ and ∊ for His Nδ and N∊, respectively. Values of pKa are calculated from the 1H NMR spectroscopic measurements published by Sun et al. (1997  ) and Fang et al. (1999). N/D, not determined; N/A, not applicable. H/D-exchange studies published by Ohe & Kajita (1980) calculated the pKa values for the individual His residues for deoxy and CO human hemoglobin. N/T, not titratable. The pKa values calculated by molecular mechanics for oxy Hb (PDB 2dn3) and deoxy Hb (PDB 2dn2) were published by Zheng et al. (2013). The color-coding indicates support of the Bohr effect (green), marginal support (yellow) and counter-support (red). |
![[Figure 2]](mn5110fig2.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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