title: The Dynamic Nonprime Binding of Sampatrilat to the C-Domain of Angiotensin-Converting Enzyme.
abstract: Sampatrilat is a vasopeptidase inhibitor that inhibits both angiotensin I-converting enzyme (ACE) and neutral endopeptidase. ACE is a zinc dipeptidyl carboxypeptidase that contains two extracellular domains (nACE and cACE). In this study the molecular basis for the selectivity of sampatrilat for nACE and cACE was investigated. Enzyme inhibition assays were performed to evaluate the in vitro ACE domain selectivity of sampatrilat. The inhibition of the C-domain (Ki= 13.8 nM) by sampatrilat was 12.4-fold more potent than that for the N-domain (171.9 nM), indicating differences in affinities for the respective ACE domain binding sites. Interestingly, replacement of the P2group of sampatrilat with an aspartate abrogated its C-selectivity and lowered the potency of the inhibitor to activities in the micromolar range. The molecular basis for this selective profile was evaluated using molecular modeling methods. We found that the C-domain selectivity of sampatrilat is due to occupation of the lysine side chain in the S1and S2subsites and interactions with Glu748 and Glu1008, respectively. This study provides new insights into ligand interactions with the nonprime binding site that can be exploited for the design of domain-selective ACE inhibitors.
authors.affiliation: Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa.
authors.forename: Rajni K
authors.initials: RK
authors.lastname: Sharma
authors.affiliation: Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa.
authors.forename: Marlene
authors.initials: M
authors.lastname: Espinoza-Moraga
authors.affiliation: Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca , 2 Norte 685, Casilla 721, Talca, Chile.
authors.forename: Horacio
authors.initials: H
authors.lastname: Poblete
authors.affiliation: Institute of Infectious Disease and Molecular Medicine and Department of Integrative Biomedical Sciences, University of Cape Town , Observatory 7935, South Africa.|Department of Integrative Biomedical Sciences, University of Cape Town , Observatory 7925, South Africa.
authors.forename: Ross G
authors.initials: RG
authors.lastname: Douglas
authors.affiliation: Institute of Infectious Disease and Molecular Medicine and Department of Integrative Biomedical Sciences, University of Cape Town , Observatory 7935, South Africa.|Department of Integrative Biomedical Sciences, University of Cape Town , Observatory 7925, South Africa.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Sturrock
authors.affiliation: Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca , 2 Norte 685, Casilla 721, Talca, Chile.
authors.forename: Julio
authors.identifier: 0000-0003-0182-1444
authors.initials: J
authors.lastname: Caballero
authors.affiliation: Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa.|Institute of Infectious Disease and Molecular Medicine, University of Cape Town , Rondebosch 7701, South Africa.|South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town , Rondebosch 7701, South Africa.
authors.forename: Kelly
authors.identifier: 0000-0002-1327-4727
authors.initials: K
authors.lastname: Chibale
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008698:Mesylates / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D007703:Peptidyl-Dipeptidase A / Q000737:chemistry / Q000378:metabolism*; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D000072417:Protein Domains; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D008698:Mesylates; D011480:Protease Inhibitors; D014443:Tyrosine; C488034:ACE protein, human; D007703:Peptidyl-Dipeptidase A; C111998:sampatrilat