Peptidomimetics-Tailored Enzyme Inhibitors

Peptides and proteins (there is no clear boundary between the two classes of compounds) are absolutely essential components of organisms in many ways. While proteins have biocatalytic functions and are important components of tissues, peptides play an important role in the organism as hormones, neurotransmitters, and neuromodulators. Peptides and their analogues have long been used in medicinal chemistry as therapeutic agents for pathological conditions generally characterized by a disruption of the interplay between messenger molecules or enzyme substrates and their targets, the receptors and enzymes. For various biochemical and biophysical reasons there is an increasing tendency towards the use of chemical “Trojan horses” known as peptidomimetics. The chances that such agents are active generally increase with the magnitude of the “deceptive effect”, in other words in proportion to the degree of conversion of a peptide into a non‐peptide. Rational design has become a catchphrase which is at present applied frequently to the development of peptidomimetics. New computer programs are invaluable tools in such design processes. However, in spite of the many advances already made, we are still far from the final goal, the de novo design of peptidomimetics. Rational design is nonetheless advancing rapidly, and it is already clear that developments in the area of peptidomimetics have given a great boost to peptide chemistry as a whole. This can be expected to continue, so that in future peptide chemistry may be characterized by a type of symbiotic alliance between peptides and non‐peptides. How should a peptide be altered to give an active drug? Tailored mimetics may not be available by de novo design in the near future, but refined conformational analyses and computer programs currently contribute to rational design beyond purely empirical observations. Compound 1, a peptoid‐based ACE inhibitor with low toxicity obtained in this way, is now in clinical trials.