title: Synthesis and biological activity of a ketomethylene analogue of a tripeptide inhibitor of angiotensin converting enzyme.
abstract: An analogue of a tripeptide inhibitor of angiotensin converting enzyme, Bz-Phe-Gly-Pro, has been synthesized in which the amide bond connecting phenylalanine and glycine has been replaced by a ketomethylene group. This nonpeptide analogue, 20, shows more potent converting enzyme inhibiting activity, I50 = 0.07 microM, than Bz-Phe-Gly-Pro, I50 = 9.4 microM, or than the orally active D-3-mercapto-2-methylpropanoyl-L-proline (captopril, 1), I50 = 0.30 microM. Compound 20 has a Ki of 1.06 X 10(-7) and either competitive or noncompetitive enzyme kinetics depending on what substrate is used in the converting enzyme assay. In tests for inhibition of angiotensin I induced contractions in the guinea pig ileum, 20 has one-tenth the activity of 1.
mesh_terms: D000803:Angiotensin I / Q000037:antagonists & inhibitors; D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D004151:Dipeptides / Q000138:chemical synthesis* / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D004151:Dipeptides; C028342:compound 20; D000803:Angiotensin I