New Features of Amyloid Found after Digestion with Trypsin

Since Cohen and Calkins in 1959 (6) described amyloid as composed of fibrils, there have been differing reports about the fibril width and the presence or size of l inear or globtflar subunits in the fibril. Originally, the width of the human amyloid fibril was estimated at 70 to 140 A. Later estimates of the width varied from 50 to 300 A (I, 2, 4, 5, 7, 12, 19-21, 23, 24). There have been relatively few high resolution studies of the individual fibrils (2, 3, I1, 19, 21-23). In these papers, estimates of the fibril width vary from 50 to 1 I0 A.