Peptides as Drugs

Protein-protein and protein-peptide interactions are key interactions for regulatory processes or signal transmission in biological environments. They are involved in cellular uptake, signal transduction, degradation processes, gene expression, cellular motility, immune responses such as antigen-antibody interactions or recognition by immune cells, blood coagulation cascade, viral entry into the cell and many more. As protein-peptide interactions are related to a whole plethora of diseases, they are of particular interest in medicinal chemistry. They offer a great potential for the application as therapeutics due to their high selectivity, e.g. as natural hormones. Peptides are based on amino acids resulting in nontoxic degradation and in no accumulation of these degradation products. The major drawback of using peptides as drugs is the poor pharmacokinetic, with typically poor bioavailability and immediate degradation by proteases. However, these drawbacks can be lessened by introducing chemical modifications which are not common in biological systems, opening the field of type I peptidomimetics. The potential modifications include the usage of unnatural or d-amino acids, backbone/side chain cyclisation, backbone modifications and many more.