Appraisal of sildenafil binding on the structure and promiscuous esterase activity of native and histidine-modified forms of carbonic anhydrase II.

Sildenafil was investigated for its interaction with the native and modified human carbonic anhydrase II (hCA II). Modification of exposed histidine side chains with diethyl pyrocarbonate decreased esterase activity of the enzyme. The treatment of both native and modified CA with sildenafil revealed slight and moderate enzyme activation profiles, respectively.