title: Calorimetric analysis of lisinopril binding to angiotensin I-converting enzyme.
abstract: Isothermal titration microcalorimetry has been used to measure changes in enthalpy and heat capacity for binding of lisinopril to the angiotensin I-converting enzyme (ACE; EC 3.4.15.1) and to its apoenzyme at pH 7.5 over a temperature range of 15-30 degrees C. Calorimetric measurements indicate that lisinopril binds to two sites in the monomer of both holo- and apo-ACE. Binding of lisinopril to both systems is enthalpically unfavorable and, thus, is dominated by a large positive entropy change. The enthalpy change of binding is strongly temperature-dependent for both holo- and apo-ACE, arising from a large heat capacity change of binding equal to -2.4 +/- 0.2 kJ/K/mol of monomeric holo-ACE) and to -1.9 +/- 0.2 kJ/K/mol of monomeric apo-ACE), respectively. The negative values of deltaCp for both systems are consistent with burial of a large non-polar surface area upon binding. Although the binding of lisinopril to holo- and apo-ACE is favored by entropy changes, this is more positive for the holoenzyme. Thus, the interaction between Zn2+ and lisinopril results in a higher affinity of the holoenzyme for this drug due to a more favorable entropic contribution.
authors.affiliation: Departamento de Química Física, Bioquímica y Química Inorgánica, Facultad de Ciencias Experimentales, La Cañada de San Urbano, Universidad de Almería, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Téllez-Sanz
authors.forename: L
authors.initials: L
authors.lastname: García-Fuentes
authors.forename: C
authors.initials: C
authors.lastname: Barón
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000378:metabolism*; D000818:Animals; D001051:Apoenzymes / Q000378:metabolism; D002151:Calorimetry; D002417:Cattle; D003067:Coenzymes / Q000378:metabolism; D017706:Lisinopril / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D011485:Protein Binding; D013816:Thermodynamics
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D001051:Apoenzymes; D003067:Coenzymes; D017706:Lisinopril; D007703:Peptidyl-Dipeptidase A