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. Author manuscript; available in PMC: 2009 Nov 4.
Published in final edited form as: Biochemistry. 2008 Oct 9;47(44):11625–11636. doi: 10.1021/bi8015636

Figure 3.

Figure 3

Temperature dependence of the apo-MnSOD gating equilibrium. (Left) pH titration isotherms measured for Co2+ uptake by apo-MnSOD at temperatures T = 25 - 49°C at 2°C intervals (1-13). Data were fit to a modified Henderson-Hasselbalch equation as described in the text and the fitted lines are shown. (Right) Apparent pKa values for metal uptake determined for temperatures ranging from 25°C to 49°C are shown with a polynomial fit to guide the eye. Inset: van'T Hoff analysis of the temperature-dependent apparent pKa for the gating transition. Van'T Hoff parameters: (1) high temperature limit, ΔHvH = 160 kJ/mol, ΔSvH = 450 J/mol·K. (2) low temperature limit, ΔHvH = 70 kJ/mol, ΔSvH = 164 J/mol·K.