The three amino acids at the C-terminus of pep63 are not necessary for its interaction with soluble Aβ oligomers

[Display omitted] •The amino acids at the N-terminus of pep63 are essential for binding soluble Aβ oligomers.•The three amino acids at the C-terminus of pep63 are not essential for binding soluble Aβ oligomers.•Removing 3 C-terminus amino acids doesn't affect pep63's disruption of the interaction between EphB2 and soluble Aβ oligomers. Soluble β-amyloid oligomers (SAβOs) are linked to early Alzheimer’s disease (AD) cognitive decline. Our previous work identified pep63, a neuroprotective peptide composed of ten amino acids, that blocks EphB2-SAβO interaction and improves the cognitive dysfunction in an AD mouse model. In this study, we constructed fourteen truncated variants of pep63 to find the key sequences for SAβO binding. Results of the peptide array assay showed that all the N-terminal truncated variants showed a significant decrease in their abilities to bind SAβOs, indicating that the amino acids at the N-terminus are essential for pep63-SAβO interaction. However, for the C-terminal truncated variants, the deletion of the terminal one, two, or three amino acids did not affect the binding of pep63 to SAβOs. Further studies indicated that the removal of the three amino acids at the C-terminus did not affect the ability of pep63 to interfere with the EphB2-SAβO interaction in vitro. Together, these results suggest that the three amino acids at the C-terminus of pep63 are not necessary for pep63-SAβO interaction, and subsequent research could consider the therapeutic strategy using a truncated form of pep63 without the corresponding amino acids. Our data provide clues and a basis for guiding the further optimization and modification of pep63.