Topooptical investigations and enzymatic digestions on tissue-isolated amyloid fibrils.

Chemical and biochemical analysis of isolated amyloid fibrils reveals the presence of different classes of proteins which are often related to distinct clinical forms of amyloidosis and are useful to classify the amyloid deposits. In this study, enzymatic digestions using hyaluronidase, chondroitinase AC and B, neuraminidase, and chemical extractions using mild acid hydrolysis with hydrochloric and sulfuric acid, were used to control the specificity of various topooptical reactions. The disappearance of intense staining after these extraction methods indicates that tissue-isolated amyloid fibrils contain sialic acids and glycosaminoglycans (GAGs). We conclude that topooptical reactions are the most sensitive methods to detect conformational changes in the non-fibrillar component of amyloid deposits and tissue-isolated amyloid fibrils.