Amyloid fibril formation by a synthetic peptide from a region of human acetylcholinesterase that is homologous to the Alzheimer's amyloid-beta peptide.

A region near the C-terminus of human acetylcholinesterase (AChE) is weakly homologous with the N-terminus of the Alzheimer's disease amyloid-beta peptide. We report that a 14-amino acid synthetic polypeptide whose sequence corresponds to residues 586-599 of the human synaptic or T form of AChE assembles into amyloid fibrils under physiological ...
conditions. The fibrils have all the classical characteristics of amyloid: they have a diameter of 6-7 nm and bind both Congo red and thioflavin-T. Furthermore, the kinetics of assembly indicate that fibril formation proceeds via a two-step nucleation-dependent polymerization pathway, and a transition in the peptide conformation from random coil to beta-sheet is observed during fibril formation using far-UV circular dichroism spectroscopy. We also show that the peptide in aggregated fibrillar form has a toxic effect upon PC-12 cells in vitro. AChE normally resides mainly on cholinergic neuronal membranes, but is abnormally localized to senile plaques in Alzheimer's disease. Recently, an in vitro interaction between AChE and A beta, the principal constituent of the amyloid fibrils in senile plaques, has been documented. The presence of a fibrillogenic region within AChE may be relevant to the interaction of AChE with amyloid fibrils formed by Abeta.
Mesh Terms:
Acetylcholinesterase, Alzheimer Disease, Amyloid beta-Protein, Animals, Biotinylation, Cell Division, Circular Dichroism, Coloring Agents, Congo Red, Fluorescent Dyes, Humans, Microscopy, Electron, Neurofibrillary Tangles, PC12 Cells, Peptide Fragments, Protein Binding, Rats, Thiazoles
Biochemistry
Date: Nov. 19, 2002
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