In vitro fibrillogenesis of interstitial collagens: electron microscopical studies of long-spacing forms induced by chondroitin sulfate.

Reaggregation behaviour of the three interstitial types of collagen was studied. Pure solutions were prepared and reprecipitation performed by the addition of chondroitin sulfate. The sediments were analyzed in the electron microscope. Classical types of fibrous long spacing collagen could be prepared only from solutions of type I collagen. Segments with an average length of 460 nm and a central overlapping zone of about 120 nm were prepared from solutions of type II collagen. They were termed 'double segment long-spacing collagen' (DSLS). No cross striated fibrils or segments could be obtained from solutions of type III collagen. These results show that there are not only chemical differences between the three interstitial types of collagen but also differences in reaggregation behaviour and in the way of interaction with other macromolecules such as glycosaminoglycans.