Aggregation of β-amyloid fragments

The authors study the folding and aggregation of six chains of the beta-amyloid fragment 16-22 using Monte Carlo simulations. While the isolated fragment prefers a helical form at room temperature, in the system of six interacting fragments one observes both parallel and antiparallel beta sheets below a crossover temperature T-x approximate to 420 K. The antiparallel sheets have lower energy and are therefore more stable. Above the nucleation temperature the aggregate quickly dissolves into widely separated, weakly interacting chains.