The relationship between the aggregational state of the amyloid-beta peptides and free radical generation by the peptides

J Neurochem. 2001 Jun;77(6):1425-32. doi: 10.1046/j.1471-4159.2001.00392.x.

Abstract

In the present study, we investigated whether or not the amyloid-beta protein (Abeta) peptide itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of Abeta and Abeta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of both Abeta40 and Abeta42 with Ntert-butyl-alpha-phenylnitrone (PBN), but not in the presence of PBN alone in phosphate-buffered saline (PBS). The fact that the four-line spectrum obtained for the Abeta/PBN in PBS was completely abolished in the presence of the iron-chelating agent Desferal demonstrated the observed four-line spectrum to be iron-dependent. The present study also revealed that either Abeta40 or Abeta42 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. Both a thioflavine-T (Th-T) fluorometric assay and circular dichroism (CD) spectroscopy showed the amyloid fibril formation of Abeta in PBS to be much higher than that of Abeta in PB. Moreover, Abeta-induced cytotoxicity assays showed Abeta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus suggest that Abeta-associated free radical generation is strongly influenced by the aggregational state of the peptides.

MeSH terms

  • Alzheimer Disease / metabolism*
  • Amyloid beta-Peptides / metabolism*
  • Amyloid beta-Peptides / toxicity
  • Animals
  • Benzothiazoles
  • Cell Survival / drug effects
  • Circular Dichroism
  • Electron Spin Resonance Spectroscopy
  • Fluorescent Dyes
  • Free Radicals / analysis
  • Free Radicals / metabolism*
  • Humans
  • PC12 Cells
  • Rats
  • Thiazoles

Substances

  • Amyloid beta-Peptides
  • Benzothiazoles
  • Fluorescent Dyes
  • Free Radicals
  • Thiazoles
  • thioflavin T