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. 2001 Mar 20;98(7):3773–3777. doi: 10.1073/pnas.071493598

Figure 2.

Figure 2

Dependence of the exchange rate of Hisα103(G10) Nɛ2H proton on pH (A), and on the concentration of H+ ions in the pH range from 5.6 to 7.6 (B). (♦, ⋄) deoxy Hb; (●, ○) HbCO; (▾, ▿) oxy Hb; (□) CN-met Hb; (▵) azido-met Hb. Filled symbols: 0.1 M Bis-Tris with 0.18 M chloride ions. Open symbols: 0.1 M Tris with 0.18 M chloride ions. The solid lines correspond to nonlinear least-squares fits to Eq. 3 with the following fitted parameters: kop = (105 ± 16) s−1, kOH/kH = (6.0 ± 1.1) 10−3, kw/kH = (1.2 ± 0.4) 10−7 M and (kop + kcl)/kH = (6.2 ± 2.6) 10−7 M for deoxy Hb A, and kop = (76 ± 5) s−1, kOH/kH = 0, kw/kH = (9.4 ± 1.4) 10−8 M and (kop + kcl)/kH = (1.6 ± 0.2) 10−6 M for ligated Hb A.