Balance between Association and Dissociation Rate Constants Determines Morphology and Property of Amyloid Fibrils.

A parallel dimeric Aβ(1-40) peptide was prepared, and its structural and fibrillogenic characteristics were examined. The covalent linking of the peptide strongly facilitated the spontaneous formation of thioflavin-T-active, fibrillar aggregates rich in β strands without a lag phase. However, the aggregates formed by the dimeric peptide did not exhibit "seeding activity" to catalyze the formation of amyloid fibrils by wild-type Aβ(1-40) molecules.