Electron microscopic studies of artificial supramolecular structures from collagen solutions.

Changes in the molecular structure of collagen fibrils isolated from solutions of native tropocollagen (TC) and of soluble collagen, obtained by enzymic (ESC) and alkaline-salt (ASC) methods, were studied by electron microscopy. It was found that, under certain conditions, it is possible to derive native-like fibrils (NF), segments with long spacings (SLS) and fibrils with long spacings (FLS)_from collagen solutions, these being very similar to structures precipitated from TC. Despite the fact that more structures with clear cross-striations can be isolated from ESC than from ASC, neither enzymic nor alkali-salt treatments cause substantial changes in the molecular structure of solubilized collagen, this determining its orderly aggregation.