ELECTRONIC AND ELECTROSTATIC ASPECTS OF CARBONIC-ANHYDRASE INHIBITION BY SULFONAMIDES

A theoretical conformational analysis was performed within the AM1 framework for three benzenesulphonamide carbonic anhydrase inhibitors in their neutral and anionic forms. The theoretical reactivity and electrostatic indices obtained are compared with both the enzymic inhibitory potencies and the molecular orbital indices computed using a simple theoretical model of the carbonic anhydrase-sulphonamide complex. Finally, the inhibitory activities of the sulphonamides considered were correlated with the proton exchange and charge transfer propensities of the inhibitors. The role of the zinc ion in the inhibition mechanism seems to be mainly connected with the generation of an electrostatic field which favours the correct orientation of the SO2NH2 group and its anticipated deprotonation.