Comparison of oct-2-enyl and oct-4-enyl staples for their formation and α-helix stabilizing effects

The all-hydrocarbon i,i+4 stapling system using an oct-4-enyl crosslink is one of the most widely employed chemical tools to stabilize an α-helical conformation of a short peptide. This crosslinking system has greatly extended our ability to modulate intracellular protein-macromolecule interactions. The helix-inducing property of the i,i+4 staple has shown to be highly dependent on the length and the stereochemistry of the oct-4-enyl crosslink. Here we show that changing the double bond position within the i,i+4 staple has a considerable impact not only on the formation of the crosslink but also on α-helix induction. The data further increases the understanding of the structure-activity relationships of this valuable chemical tool.