Thermal stability of pepsin: A predictive thermodynamic model of a multi-domain protein

- The “two independent two-state transitions model” was used for analyzing of thermal denaturation of multi-domain proteins.
- ΔGDeff is a useful parameter that gives an intuitive appreciation of the stability of multimeric proteins.
- All experimental data suggests that at pH 4 the stability of pepsin is enhanced, the positive big ΔGDeff value at pH 4 in Ts=298.15 K.
- The corresponding that is a well-defined function for thermodynamic stability of multi-domain proteins reversible thermal denaturation.

Pepsin is generally used in the preparation of F(ab)2 fragments from antibodies. The antibodies that are one of the largest and fastest growing categories of bio- pharmaceutical candidates. Differential scanning calorimetric is principally suitable method to follow the energetics of a multi-domain, fragment to perform a more exhaustive description of the thermodynamics in an associating system. The thermodynamical models of analysis include the construction of a simultaneous fitting of a theoretical expression. The expression depending on the equilibrium unfolding data from multimeric proteins that have a two-state monomer. The aim of the present study is considering the DSC data in connection with pepsin going through reversible thermal denaturation. Afterwards, we calculate the homology modeling identification of pepsin in complex multi-domain families with varied domain architectures. In order to analyze the DSC data, the thermal denaturation of multimer proteins were considered, the “two independent two-state sequential transitions with domains dissociation model” was introduced by using of the effective ΔG concept. The reversible unfolding of the protein description was followed by the two-state transition quantities which is a slower irreversible process of aggregation. The protein unfolding is best described by two non-ideal transitions, suggesting the presence of unfolding intermediates. These evaluations are also applicable for high throughput investigation of protein stability.