Synthesis and Biological Properties of L -Arginyl- L -Prolyl- L -Prolyl-Glycyl- L -Phenylalanyl- L -Seryl- L -Phenylalanyl- L -Arginine, an Octapeptide related to Bradykinin

A STRUCTURE has recently been proposed 1 fox bradykinin, a plasma peptide obtained from or blood. The isolation, purification and amino-acid composition of this substance were reported earlier by the same workers 2 . The apparent importance of this peptide and its small size have prompted us to undertake its synthesis and a more detailed study of its biological action. Our first preparation of this octapeptide showed little bradykinin-like activity in several biological tests. While our synthesis and biological work were therefore being rechecked, workers 3,4 in two other laboratories reported the synthesis of this peptide and its lack of expected activity on the guinea pig's ileum. In the present communication we describe its synthesis and biological examination, which confirm and extend this recently published work.