Stability of type I collagen peptide trimers.

As indices of triple helix stability of type I collagen CNBr peptide homotrimers, Delta G degrees for monomer-trimer transitions and melting temperatures were obtained from circular dichroism measurements at increasing temperatures. The data were compared with the stability of the parent native molecule. Peptides were found to have a lower stability than the whole collagen molecule. The general implication is that the coordinated water molecules play a key role in determining collagen triple helical stability and high cooperativity at melting. Other factors (monomer stability, ionic and hydrophobic factors, variations of composition, specific sequence) could also contribute towards peptide stability; these factors could explain the data obtained in the case of peptide alpha 1(I) CB3.