Thermal stability of Helix aspersa maxima hemocyanin

Y Raynova, S Todinova, K Idakieva
2017 Bulgarian Chemical Communications   unpublished
The thermal stability of the hemocyanin, isolated from garden snails Helix aspersa maxima (HaH), was studied by differential scanning calorimetry. One transition, with an apparent transition temperature (Tm) at 79.8 o C, was detected in the thermogram of HaH in 20 mM HEPES buffer, containing 0.1 M NaCl, 5 mM CaCl2 and 5 mM MgCl2 (pH 7.06 at 80 o C), using a heating rate of 1.0 o C/min. The thermal denaturation of HaH was an irreversible process. The scan rate dependence of the calorimetric
more » ... e calorimetric profiles indicated that the thermal unfolding of the investigated Hc is kinetically controlled. Tm and ΔHcal values for the thermal denaturation of HaH were found to be independent of the protein concentration, suggesting that the dissociation of the Hc into subunits does not take place before the rate-determining step of the process of thermal unfolding started. The thermal denaturation of HaH was described by the two-state irreversible model. On the basis of this model, the parameters of the Arrhenius equation were calculated.