Controlled in situ preparation of A beta(1-42) oligomers from the isopeptide "iso-A beta(1-42)", physicochemical and biological characterization.
Beta-amyloid (A beta) peptides play a crucial role in the pathology of the neurodegeneration in Alzheimer's disease (AD). Biological experiments (both in vitro and animal model studies of AD) require synthetic A beta peptides of standard quality, aggregation grade, neurotoxicity and water solubility. The synthesis of A beta peptides has been difficult, owing to their hydrophobic character, poor solubility and high tendency for aggregation. Recently an isopeptide precursor (iso-A beta(1-42)) was synthesized by Fmoc-chemistry and transformed at neutral pH to A beta(1-42) by O-->N acyl migration in a short period of time. We prepared the same precursor peptide using Boc-chemistry and studied the transformation to A beta(1-42) by acyl migration. The peptide conformation and aggregation processes were studied by several methods (circular dichroism, atomic force and transmission electron microscopy, dynamic light scattering). The biological activity of the synthetic A beta(1-42) was measured by ex vivo (long-term potentiation studies in rat hippocampal slices) and in vivo experiments (spatial learning of rats). It was proven that O-->N acyl migration of the precursor isopeptide results in a water soluble oligomeric mixture of neurotoxic A beta(1-42). These oligomers are formed in situ just before the biological experiments and their aggregation grade could be standardized.
Bozso
Zsolt
Z
Department of Medical Chemistry, University of Szeged, Szeged, Hungary. zbozso@yahoo.com
Penke
Botond
B
Simon
Dóra
D
Laczkó
Ilona
I
Juhász
Gábor
G
Szegedi
Viktor
V
Kasza
Agnes
A
Soós
Katalin
K
Hetényi
Anasztázia
A
Wéber
Edit
E
Tóháti
Hajnalka
H
Csete
Mária
M
Zarándi
Márta
M
Fülöp
Lívia
L
D000215:Acylation; D000682:Amyloid / Q000737:chemistry; D016229:Amyloid beta-Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology* / Q000648:ultrastructure; D000818:Animals; D002021:Buffers; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000502:physiology; D002942:Circular Dichroism; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005563:Formic Acid Esters / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007276:Injections, Intraventricular; D007536:Isomerism; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008970:Molecular Weight; D010316:Particle Size; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology* / Q000648:ultrastructure; D020005:Propanols / Q000737:chemistry; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000737:chemistry; D006845:Hydrocarbons, Fluorinated
D000682:Amyloid; D016229:Amyloid beta-Peptides; D002021:Buffers; D005563:Formic Acid Esters; D010446:Peptide Fragments; D020005:Propanols; D012694:Serine; C075222:amyloid beta-protein (1-42); C000345:t-butyloxycarbonyl group; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated