[The presence of a thermally stable domain in the spiral part of a collagen molecule].

It is shown that in 0,5 M NaCl 8 M CH3COOH heat absorption and the second structure alteration in a heated solution proceed between two stages following one another, and besides, salts not only decrease the macromolecule denaturation temperature in total, but produce different destabilization effect on different regions. The presence of the thermostable domain in the macromolecule helical part permits investigation of the folding mechanism of the triple collagen helix under partial denaturation. The localization and biological role of the stable domain in the triple helix formation are suggested.