Quantum mechanical studies on neuropeptides: Conformation of C-terminal tetra- and pentapeptides of tachykinins

Tachykinins constitute an important class of neuropeptides which exhibit a wide variety of biological functions. They are responsible for exciting neurons and evoking behavioral responses. These peptides have a common C-terminal pentapeptide sequence and their biological activity depends on the minimum sequence at this end. Quantum mechanical PCILO investigations were carried out on the conformation of a number of tetra- and pentapeptide sequences. The results indicate a predominance of the extended backbone conformations for these neuropeptides. This result is discussed in the light of the biological activity of tachykinins.