A Study of the Interactions between Monomeric Tropocollagen and Glycosaminoglycans

Monomeric, lathyritic tropocollagen and a variety of well‐characterized glycosaminoglycans have been used in a light‐scattering study of the interaction that occurs between these macro‐molecules under physiological ionic conditions. Additional information has been obtained by turbidimetric and precipitation studies. A binding to collagen of chondroitin 4‐sulphates, derma‐tan sulphates, heparan sulphates, heparin and proteoglycans of chondroitin sulphate and dermatan sulphate was observed. The complex formation was electrostatic in nature and was abolished with increasing ionic strength. Keratan sulphate did not bind to collagen, indicating either that uronic acid was a prerequisite for the interaction or that a charge density of more than one negative charge per disaccharide was required. Polysaccharides which contained l ‐iduronic acid showed a stronger interaction than polysaccharides containing only d ‐glucuronic acid. As a general rule the interaction seemed to increase with increasing chain length of the polysaccharide and increasing charge density. The results of studies on mixtures of tropocollagen and proteoglycans indicated that the properties of the polysaccharide chains per se were of importance for the mode of reaction between the proteoglycans and collagen. Hyaluronic acid was not to any significant extent bound to collagen. This polysaccharide and tropocollagen affected each other by a mutual steric exclusion with a concomitant increase in the activity of the tropocollagen molecules.