Detection of beta-amyloid peptide aggregation using DNA electrophoresis.

DNA could readily associate with the aggregated forms of the beta-amyloid peptides beta(1-40) and beta(25-35), giving rise to a shift in the electrophoretic mobility of DNA. As a result, DNA was retained at the top of a 1% agarose gel. In contrast, the electrophoretic mobility of DNA was little influenced by the monomeric forms of beta(1-40) and beta(25-30). DNA from different sources such as lambda phage, Escherichia coli plasmid, and human gene showed similar results. However, the electrophoretic mobility of RNA was shifted by the monomeric beta(1-40) and beta(25-35) as well as by the aggregated beta(1-40) and beta(25-35). The association of DNA with the aggregated beta-amyloid peptides could occur at pH 4-9. The inhibitory action of hemin on beta-amyloid aggregation could be confirmed using the DNA mobility shift assay. These results indicate that the DNA mobility shift assay is useful for kinetic study of beta-amyloid aggregation as well as for testing of agents that might modulate beta-amyloid aggregation. Copyright 2000 Academic Press.