Comparative Analysis of the Structure and Fibrillogenesis of Aβ11-28 Peptide and the Inverse Sequence

The inverse sequences of naturally occurring proteins display different folding and structural properties fail to retain the functions native despite identical fundamental features, such as amino acid composition, hydrophobicity, etc. To gain insight into physical mechanisms underlying secondary structure formation aggregation direct retro amyloidogenic peptides, we probed fibrillogenesis accompanying changes amyloid β peptide fragment Aβ11-28 (EVHHQKLVFFAEDVGSNK) its sequence, Aβ28-11. These peptides are interest because both or Aβ28-11 parallel, in-register β-sheet (characteristic Aβ fibrils) will be hampered by electrostatic repulsion between acids like charges. Therefore, each is expected form antiparallel intermolecular their combination would parallel stabilized ionic interactions juxtaposed side chains with opposite Circular dichroism data identified α-helical for equimolar in hexafluoroisopropanol dry state. Addition aqueous buffer caused transition unordered state, followed β-sheet/β-turn structure, faster Aβ11-28. Thioflavin-T fluorescence showed fibril Aβ28-11, starting around 200 250 h, respectively. For combination, ThT stayed at low level 360 h. FTIR confirmed α-helix propensity sequence. slowly transitioned from mostly β-turn structure. Amide I spectral features characteristic were not detected any samples. suggest that play a minor role aggregation, sequence distinctly parent peptide.