An Influence of the Aromatic Side Chains Conformations in Positions 2 and 3 of Vasopressin Analogs on Interactions with Vasopressin and Oxytocin Receptors

In this work, the receptor-bound conformation of nine vasopressin (CYFQNCPRG-NH2, AVP) analogs substituted in positions 2 or 3 with 2-aminoindane-2-carboxylic acid have been investigated using molecular modeling methods. The synthesis and functional assays of the analogs have been recently described. For comparison, the molecular dynamics of the selected analogs has been conducted. We have observed the relationship between the value of valence angle between the aromatic rings in positions 2 and 3 and the biological activity of the analogs. Both, in restricted space of the receptor cavities and unlimited continuous water environment, the same valence angles prevail, thus seem to be energetically more favorable for the particular peptides. Moreover, the residues responsible for analogs binding to the receptors have been identified.