The binding of anionic species by peptides and proteins is a crucial recognition event in biological systems, with downstream effects ranging from structural stabilisation to catalysis. In natural systems, highly efficient and selective anion recognition is achieved through the use of large peptides and proteins that take advantage of the numerous H-bonding interactions available from a variety of amino acid side chains with additional contributions from the amide protons in the protein backbone. Metal-ligand interactions from protein-bound metal ions to anions are also common in biological anion binding.
Small synthetic peptides are ideal candidates for use as scaffolds in the generation of molecular receptors because the large number of amino acid derivatives available allows a wide variety of novel and natural anion binding groups to be attached to the scaffold and alteration of the side chains and peptide sequence allows the function, conformation and solubility of the molecules to be tuned for specific applications.
We have developed several classes of peptide based receptors bearing appropriate side chain functional groups for the recognition and sensing of oxoanions through both hydrogen bonds and metal-ligand interactions and report here on their synthesis and ability to selectively discriminate anionic targets in aqueous solution for a variety of applications.