Detection of β-Amyloid Peptide Aggregation Using DNA Electrophoresis

Abstract

DNA could readily associate with the aggregated forms of the β-amyloid peptides β(1–40) and β(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 β(1–40) and β(25–30). DNA from different sources such as λ phage, Escherichia coli plasmid, and human gene showed similar results. However, the electrophoretic mobility of RNA was shifted by the monomeric β(1–40) and β(25–35) as well as by the aggregated β(1–40) and β(25–35). The association of DNA with the aggregated β-amyloid peptides could occur at pH 4–9. The inhibitory action of hemin on β-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 β-amyloid aggregation as well as for testing of agents that might modulate β-amyloid aggregation.