One role of proline in proteins is that a β-turn of a peptide chain is being induced at its position. Two major conformations, cis or trans, of the corresponding amid bond will induce that the protein folds in a specific way.

While the trans-conformation is normally thermodynamically being preferred, cis-conformation can become favourable through specific substitutions at the pyrrolidine ring.

Hydroxylproline occurs naturally for cross-linking within collagen tripelhelices and similarly proline bearing other reactive functionalities along the ring enable to use this building block to design a third bond formation next to the peptide amide bonds.

We have access to synthesis platforms which allow us to design different chemical functionalities with defined stereochemistry at different positions of the pyrrolidine ring.