| Autor: |
Eugene R. Wiley, Philip E. McClain |
| Rok vydání: |
1972 |
| Předmět: |
|
| Zdroj: |
Journal of Biological Chemistry. 247:692-697 |
| ISSN: |
0021-9258 |
| DOI: |
10.1016/s0021-9258(19)45663-9 |
| Popis: |
Thermal transition enthalpy changes (ΔHf) were investigated in intact and soluble collagen from a variety of sources and species utilizing differential scanning calorimetry. Results indicated that the ΔHf determinations were not dependent on sample size, method of preparation, or sample purity. The ΔHf values for intact collagen were virtually identical with those from tropocollagen preparations, confirming previous conclusions that the state of aggregation or extent of covalent cross-linking plays only a minor role in the thermal stability of collagen. The experimentally determined values for the enthalpy change per residue (ΔHr) were 1055 cal per mole and appeared to be invariant in all the collagens studied. The denaturation energy per triplet averaged 3000 cal per mole, suggesting that forces other than hydrogen bonding must be contributing to denaturation enthalpy. A correlation between thermal denaturation or shrinkage temperature and total pyrrolidine content was evident. The entropy change per residue also increased with decreasing imino acid content. These results tend to support the conclusion that the tertiary superhelix structure of the collagen molecule is stabilized primarily by the steric restrictions imposed by the pyrrolidine residues. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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