alpha-Synuclein is the major components of the intracellular protein-aggregates, found in the dopaminergic neurons of Parkinson's disease patients. Previously, we screened for alpha-synuclein substitution mutants that prevent fibril formation of both wild-type and Parkinson's disease-linked alpha-synuclein variants. In the present study, we show that short synthetic peptides derived from these mutant sequences not only prevented alpha-synuclein fibrillation but also dissolved preformed alpha-synuclein aggregates in vitro. The hexapeptide PGVTAV, which was the shortest peptide that retained the ability to block alpha-synuclein fibrillation, may serve as a lead compound for the development of therapeutics for Parkinson's disease. (C) 2009 Elsevier Inc. All rights reserved.