Denaturant-unfolded apomyoglobin

Figure 6.21 (a) Kratky plot recorded with urea-denatured (unfolded) apomyoglobin in buffer solution at pH 6.0. Adapted with permission from Ref [73] 2007, American Chemical Society (b) Schematic... 

The thermal stability of metmyoglobin and apomyoglobin has been extensively studied under different solvent conditions (Privalov et al., 1986). In particular, it was shown that at low pH values both the heat and cold denaturation peaks are clearly visible in the calorimetric scans. Figure 10 shows the excess heat capacity function for apomyoglobin predicted by the hierarchical partition function and the thermodynamic parameters described above. In order to simulate the experimental curve obtained at pH 3.83 (Privalov et al., 1986), the protonation of five specific histidine residues on unfolding was... 

We conclude this discussion with some recent data on denaturation and refolding of sperm whale myoglobin and apomyoglobin (Shen and Hermans (76)). Kinetic data on the refolding of this protein are potentially extremely valuable because a) the conformation of myoglobin is known, and b) the unfolding equilibrium is particularly well understood (34). The equilibrium follows a two state description, and, furthermore, free... 

Barrick, D., Hughson, F.M., and Baldwin, R.L., 1994, Molecular mechanisms of acid denaturation - the role of histidine residues in the partial unfolding of apomyoglobin, J. Mol Biol. 237 588-601. 

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