Effect of agitation on the peptide fibrillization: Alzheimer's amyloid-β peptide 1-42 but not amylin and insulin fibrils can grow under quiescent conditions.

Many peptides and proteins can form fibrillar aggregates in vitro, but only a limited number of them are forming pathological amyloid structuresin vivo. We studied the fibrillization of four peptides Alzheimer's amyloid- (A) 1-40 and 1-42, amylin and insulin. In all cases, intensive mechanical agitation of the solution initiated fast fibrillization. However, when the mixing was stopped during the fibril growth phase, the fibrillization of amylin and insulin was practically stopped, and the rate for A40 substantially decreased, whereas the fibrillization of A42 peptide continued to proceed with almost the same rate as in the agitated conditions. The reason for the different sensitivity of the in vitro fibrillization of these peptides towards agitation in the fibril growth phase remains elusive. Copyright (c) 2013 European Peptide Society and John Wiley & Sons, Ltd.