Characterization of Acid-Soluble Type I Collagen in Solution by Viscosity Measurements. I. Some evidence about adsorption on the glass material and about electrostatic and ionic bondings in the molecular self assembly process

Abstract

The evidence of a adsorption phenomenon of the acid-soluble collagen molecules on the glass material is shown. A way of calculation is proposed from viscosimetric measurements. It could be pointed out that a small amount corresponding to 4 to 5% of the collagenous concentration is involved in such a adsorption process, at 25 °C. This adsorption phenomenon is temperature-dependent and weakened by a previous NaOH-treatment of the collagen solutions.

It is confirmed that intermolecular associations may take place in acidic conditions and they are minimized for a pH range corresponding to the pK area of aspartic and glutamic acid residues. The influence of temperature showed that ionic interactions are reinforced by hydrophobic effects. The modification of the ionization and the removal of the telopeptidic regions from the native molecules are responsible for the decrease in these associations. On the other hand, it was shown that the relative flexibility of the molecule may explain the modifications in the {η} values depending on the pH and ionic-strength conditions for the molecular solutions.