Amyloid-beta-protein (A beta) (25-35)-associated free radical generation is strongly influenced by the aggregational state of the peptides.
We investigated whether or not the Amyloid-beta-protein (A beta) itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of A beta and A beta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of A beta25-35 with N-tert-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 A beta25-35/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. On the other hand, A beta25-35 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. the present results showed the amyloid fibril formation of A beta25-35 in PBS to be much higher than that of A beta25-35 in PB. Moreover, A beta-induced cytotoxicity assays showed A beta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus demonstrate that A beta(25-35)-associated free radical generation is strongly influenced by the aggregational state of the peptides.
Monji
Akira
A
Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. amonji@hf.rim.or.jp
Utsumi
Hideo
H
Ueda
Tadashi
T
Imoto
Taiji
T
Yoshida
Ichiro
I
Hashioka
Sadayuki
S
Tashiro
Ken-ichiro
K
Tashiro
Nobutada
N
D000544:Alzheimer Disease / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism* / Q000633:toxicity; D000818:Animals; D003497:Cyclic N-Oxides; D003676:Deferoxamine / Q000494:pharmacology; D004336:Drug Antagonism; D004578:Electron Spin Resonance Spectroscopy; D005562:Formazans / Q000378:metabolism; D005609:Free Radicals / Q000032:analysis / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D016716:PC12 Cells / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism* / Q000633:toxicity; D020836:Protein Structure, Quaternary; D051381:Rats; D013778:Tetrazolium Salts / Q000378:metabolism
D016229:Amyloid beta-Peptides; D003497:Cyclic N-Oxides; D005562:Formazans; D005609:Free Radicals; D009589:Nitrogen Oxides; D010446:Peptide Fragments; D013778:Tetrazolium Salts; C074636:amyloid beta-protein (25-35); C079782:MTT formazan; C029217:phenyl-N-tert-butylnitrone; D003676:Deferoxamine