Investigation of recrystallization of collagen (I) employing contraction and statistical conformation properties
The ability of collagen (I) to recrystallize by cooling after a thermal denaturation was attempted by a method of concentration energy and theoretical statistical conformation analysis. Contraction energy of the native collagen was 1.96 ± 0.6 J/g; that of denaturated collagen after cooling in contracted state 0.036 J/g and in the stretched state 0.45 ± 0.1 J/g. This corresponds to a 1.8 and 22.8% of recrystallization, respectively. Theoretic calculation of the probable conformation of the whole sequence of α1(I) chain showed that approximately only 60% of sequences have the ability to form spontaneously stretched polypyrrolidine conformation, whereas approximately 34% of the chain was randomized. About 5% of amino acid sequences had a preferred α-helical conformation and terminal peptides, especially the C-tail have a high probability of extended conformation of a β-pleated sheat type. The collagen chain reveals a significant tendency to form reverse turn. Statistical conformation properties are compared with those of some model polypeptides.