Engineering stabilized vascular endothelial growth factor-A antagonists: synthesis, structural characterization, and bioactivity of grafted analogues of cyclotides

J Med Chem. 2008 Dec 25;51(24):7697-704. doi: 10.1021/jm800704e.

Abstract

Cyclotides are plant derived mini-proteins with compact folded structures and exceptional stability. Their stability derives from a head-to-tail cyclized backbone coupled with a cystine knot arrangement of three-conserved disulfide bonds. Taking advantage of this stable framework we developed novel VEGF-A antagonists by grafting a peptide epitope involved in VEGF-A antagonism onto the stable cyclotide framework. Antagonists of this kind have potential therapeutic applications in diseases where angiogenesis is an important component of disease progression, including cancer and rheumatoid arthritis. A grafted analogue showed biological activity in an in vitro VEGF-A antagonism assay at low micromolar concentration and the in vitro stability of the target epitope was markedly increased using this approach. In general, the stabilization of bioactive peptide epitopes is a significant problem in medicinal chemistry and in the current study we have provided insight into one approach to stabilize these peptides in a biological environment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemistry, Pharmaceutical / methods
  • Cyclotides / chemistry*
  • Cystine Knot Motifs
  • Drug Delivery Systems
  • Drug Design
  • Epitopes / chemistry
  • Hemolysis
  • Humans
  • Hydrogen-Ion Concentration
  • Models, Chemical
  • Molecular Conformation
  • Neovascularization, Pathologic
  • Protein Structure, Tertiary
  • Vascular Endothelial Growth Factor A / antagonists & inhibitors*

Substances

  • Cyclotides
  • Epitopes
  • Vascular Endothelial Growth Factor A