Substrate Dependence of Angiotensin I-Converting Enzyme Inhibition: Captopril Displays a Partial Selectivity for Inhibition ofN-Acetyl-Seryl-Aspartyl-Lysyl-Proline Hydrolysis Compared with That of Angiotensin I

• Published in: Molecular pharmacology 1997-06, Vol.51 (6), p.1070-1076
• Main Authors: Michaud, Annie, Williams, Tracy A., Chauvet, Marie-Thérèse, Corvol, Pierre
• Format: Article
• Language: English
• ISSN: 0026-895X
• DOI: 10.1124/mol.51.6.1070

Angiotensin I-converting enzyme (ACE) is composed of two highly similar domains (referred to here as the N and C domains) that play a central role in blood pressure regulation; ACE inhibitors are widely used in the treatment of hypertension. However, the negative regulator of hematopoiesis, N-acetyl-seryl-aspartyl-lysyl-prolyl (AcSDKP), is a specific substrate of the N domain-active site; thus, in addition to the cardiovascular function of ACE, the enzyme may be involved in hematopoietic stem cell regulation, raising the interest of designing N domain-specific ACE inhibitors. We analyzed the inhibition of angiotensin I and AcSDKP hydrolysis as well as that of three synthetic ACE substrates by wild-type ACE and the N and C domains by using a range of specific ACE inhibitors. We demonstrate that captopril, lisinopril, and fosinoprilat are potent inhibitors of AcSDKP hydrolysis by wild-type ACE, withKi values in the subnanomolar range. However, of the inhibitors tested, captopril is the only compound able to differentiate to some degree between AcSDKP and angiotensin I inhibition of hydrolysis by wild-type ACE: theKi value with AcSDKP as substrate was 16-fold lower than that with angiotensin I as substrate. This raises the possibility of using captopril to enhance plasma AcSDKP levels with the aim of normal hematopoeitic stem cell protection during chemotherapy and a limited effect on the cardiovascular function of ACE.