in a continued effort to relate the three-dimensional structure of a peptide hormone to its biological activity , the dose-response relationships of [ 3-phenylalanine ] oxytocin ( oxypressin ) , with an aromatic amino acid residue in position 3 , and [ 3-beta-cyclohexylalanine ] oxytocin , with an aliphatic amino acid residue to position 3 , were determined in the rat uterine assay in vitro and compared to that of oxytocin .
C0031453
phenylalanine
C0301713
aromatic amino acid