Application of Kissinger, isoconversional and multivariate non-linear regression methods for evaluation of the mechanism and kinetic parameters of phase transitions of type I collagen

DSC measurements carried out on type I collagen at different heating rates were used for the kinetic analysis of the endothermic processes of denaturation in water excess and of the phase transition in dry state. The application of isoconversional and “multivariate non-linear regression” methods shows that in both conditions the phase transitions are complex processes exhibiting Lumry-Eyring mechanism (a reversible step followed by an irreversible one), which describes the denaturation of several proteins. The corresponding kinetic parameters were evaluated, and were used for simulation of the thermal behavior of type I collagen in both considered conditions, in non-isothermal regime at different heating rates, as well as in isothermal regime at different temperatures. It was obtained that at relatively low heating rates and temperatures, the investigated complex processes could be satisfactorily described from kinetic point of view by a single step irreversible process.