Influence of PH on thermodynamic stability of rat tail type 1 procollagen.
2022
We have carried out a DSC research of acid diluted procollagen of rat tail, which mainly contains type I collagen. The research was conducted within pH interval of 1.5 to 3.9 in presence of NaCl with physiological concentration. It is shown, that the melting process of procollagen in pH interval of 3.9-2.1 has two stages, and the melting process shifts to lower temperatures with decrease in pH, with minor changes in melting enthalpy (ΔHm). The melting parameters of procollagen at pH3.9 is T1m=32.6°C, 2 T2m=36.7°C and ΔHm=17.5±1 cal/g. Within pH interval of 1.7-1.5, the melting process has one stage, and at pH1.5 the melting parameters are: Tm=28.2°C, ΔTm=1.5°C, and ΔHm=15.2±0.9 cal/g. Decreasing in ΔHm by 2 cal/g is in correlation with the dependence ΔHm=f(t) that is commonly used for proteins. Thus, correspondence of the melting at pH1.5 with the melting enthalpy at pH3.9 and the high cooperativity of collagen melting process indicate that the individual triple helix chains of rat tail procollagen at pH1.5 preserves its native conformation. These results directly indicate that it is recommended to extract the procollagen at pH1.5 when collagen solubility is at least 10 times higher than at pH3.9. The abovementioned features of the rat tail procollagen, the physico-chemical parameters of which is close to all mammalian procollagens, and nativeness at pH1.5 are important as for pharmaceuticals so for food industry. Fig. 1, Ref. 10.
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