QM Study of complex between Acetazolamide inhibitor and human α-carbonic anhydras enzyme

In the present research, the effect of a classical sulfonamide inhibitor, namely acetazolamide on human carbonic anhydrase reaction has been investigated by employing DFT method. Carbonic anhydrase is an enzyme found in red blood cells and many other tissues. Also all thermodynamic functions such as deprotonation enthalpy of inhibitor (ΔH 0), standard enthalpies of complexation, standard entropy of complexation (ΔS com 0) and standard Gibbs free energy of complexation (ΔG com 0) for CA–inhibitor complex are evaluated. The calculated results indicate that deprotonated inhibitor is coordinated to the Zn2+ ion and the [enzyme/inhibitor] complex has tetrahedral geometry. According to the calculated thermodynamic functions substitution of sulfonamide group with hydroxyl reduces the tendency of inhibitor to bind to the active center of carbonic anhydrase.