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Selection of Captopril Isomerization States by human Angiotensin I Converting Enzyme (hACE)
Author(s) -
Naqvi Nawazish,
Tzakos Andreas G.,
Comporozos Konstantinos,
Piaratelli Roberta,
Troganis Anastassios,
Theodorou Vassiliki,
Gerothanassis Ioannis P.,
Husain Ahsan
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a50-a
Subject(s) - chemistry , isomerization , stereochemistry , docking (animal) , captopril , enzyme , moiety , mutant , active site , computational chemistry , biochemistry , medicine , nursing , gene , blood pressure , catalysis , radiology
In the enzyme–inhibitor recognition process, the enzyme selects only those states of the inhibitor presenting architectural and stereoelectronic complementarity with its binding groove. In order to shed light towards this recognition process, a novel combinatorial approach exploiting solution NMR, flexible docking calculations, mutagenesis and enzymatic studies was applied to hACE and its inhibitor captopril. Detailed H NMR studies of the two isomerization states (cis/trans) of the proline moiety of captopril were recorded as a function of pH and solvent. Remarkably, a similar cis‐to‐trans ratio was observed at physiological pH. Docking calculations of both states of the inhibitor to the mutant Y1096F of hACE estimated similar free energies of binding indicating that both states could be accommodated with the same probability. Kinetic studies on Y1096F best fit using a two site model, whereas data for wild type hACE and K1087A mutant fit on one site model suggesting multiple conformational states for the inhibitor. We suggest that the observed equimolar ratio of the two inhibitor states in solution is related to the two states observed in our kinetic studies for the Y1096F. These results pinpoint the importance of the multiple conformational states of the inhibitor that should be taken into account in the frame of the drug design process so as to increase the maximum inhibitor usage by the enzyme.