Poster Presentation 8th Modern Solid Phase Peptide Synthesis & Its Applications Symposium 2022

Towards the synthesis of the unique pseudo-homodimer aD-VxXXB (#112)

Thao Ho 1 , Nikita Abraham 1 , Richard Lewis 1
  1. Institute for Molecular Bioscience, the University of Queensland, St Lucia, QLD, Australia

VxXXB is a pseudo-homodimer aD-conotoxins that allosterically inhibits nAChRs with high potency. However, challenges synthesising aD-conotoxins have hindered further studies on this interesting class of peptides. To address this gap, in Chapter 4, we synthesised and characterised its C-terminal domain (CTD) and N-terminal domain (NTD). VxXXBCTD retained inhibitory activity at α7 nAChRs and an allosteric binding mode at AChBP, albeit with a lower potency compared to the full-length homodimer VxXXB. The anti-parallel dimeric VxXXB NTD synthesised via a regio-selective strategy was also inhibitory but with reduced potency at α7 nAChRs. Several ligation strategies were then trialed for the synthesis of an VxXXB variant comprising of a CTD linked to an NTD (VxXXB NC), and also the full-length synthetic VxXXB CNC. The α-ketoacid-hydroxylamine (KAHA) method yielded expected ligated products, in which the synthetic full-length VxXXB CNC exhibited a 2-fold higher potency at α7 nAChRs compared to the VxXXB NC. This work allows for further characterisation of the challenging aD-conotoxin pharmacology, specifically the structure-function relationship of VxXXB at nAChR and the development and characterization of truncated allosteric inhibitors of the nAChR.