Synthesis of des(tetrapeptide B(1-4)) and des(pentapeptide B(1-5)) human insulins. Two biologically active analogues.

Two analogues of human insulin, des(tetrapeptide B(1-4))-and des (pentapeptide B(1-5))-insulin, which differ from the parent molecule in that the N-terminal tetrapeptide and pentapeptide sequences, respectively, have been eliminated, have been synthesized. The des(tetrapeptide B(1-4))-insulin shows potencies of 13 IU/mg by the mouse convulsion assay method and 7.6 IU/mg by the radioimmunoassay method. The des(pentapeptide B(1-5))-insulin possesses a potency of 1.2 IU/mg when assayed by the glucose-oxidation method in isolated fat cells and 3.7 IU/mg by the radioimmunoassay technique. The natural hormone has a potency of 23--25 IU/mg by both assay methods.