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Figure 3: Hemichrome formation test for monomeric bovine heart Mb. (a) Tracing of DSC curve for unfolding of bovine heart MbO2 in 0.1 M HEPES buffer at pH 7.4. Protein concentration was 2.35 mg ml-1 (0.91 mM). (b) By means of DSC, the properties of thermal unfolding of bovine heart MbO2 and metMb were depicted as a function of pH and temperature in terms of Td (i.e., the temperature at which the transition is half complete). Protein concentration was 1.5 −5.5 mg ml-1 (0.91 to 5.81 mM) ○: MbO2, △: metMb. (c) Temperature dependence of first-order rate constants, kA of autoxidation of bovine heart MbO2. The autoxidation was measured in 0.1 M buffer at a given pH and temperature under air saturated condition. The resulting data of pH 5.0 in 0.1 M MES buffer (○), 6.0 in 0.1 M MES buffer (△), 7.0 in 0.1 M HEPES buffer () and 9.0 in 0.1 M CHES buffer () were plotted against a given temperature. MbO2 concentration was 97μM. (d) Arrhenius plot of kA, measured in 0.1 M HEPES buffer at pH 7.4.
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