The structural requirements of oxytocin and vassopressin analogues for the activation of adenylate cyclase in the rat kidney medullary membrane system

Abstract

The binding properties and the activation of adenylate cyclase by the structural analogues of neurohypophysial hormones in the rat kidney membrane system were investigated. Certain structural modifications of the vasopressin molecule, i.e. absence of the primary amino group, removal of the carboxy-terminal part and combinations of the modifications lowered the affinity and activating properties of the compounds. A similar effect was observed in the oxytocin series where the absence of the primary amino group decreased the binding and activation of the adenylate cyclase. Two modifications improved the binding affinity: the carba substitution in both the series of deamino-analogues and the introduction of a lipophilic substituent in the para-position of the aromatic amino acid in position 2 of the peptide chain. An attempt was made to correlate the binding and activating properties with the biological effects.