Transient formation of nano-crystalline structures during fibrillation of an A-like peptide

• During the first few minutes of fibrillation of a 14-residue peptide homologous to the hydrophobic C-terminal part of the A-peptide, EM micrographs reveal small crystalline areas (100 to 150 nm, repeating unit 47 Å) scattered in more amorphous material. On a longer time scale, these crystalline areas disappear and are replaced by tangled clusters resembling protofilaments (hours), and eventually by more regular amyloid fibrils of 60 Å to 120 Å diameter (days). The transient population of the crystalline areas indicates the presence of ordered substructures in the early fibrillation process, the diameter of which matches the length of the 14-mer peptide in an extended -strand conformation.

Nyckelord

peptide aggregation

protein aggregation

amyloid fibrils

peptide crystal

electron microscopy

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