The surface rendition of hCA-IX (PDB ID: 3iai) in gray representation, illustrating the deeply anchored co-crystallized acetazolamide (sticks) into the active site cleft; the prosthetic Zn(II) (magenta sphere), as well as the hydrophilic (purple) and hydrophobic (orange) residues are shown. The zoomed image is the stereo view of acetazolamide (sticks; green as carbon, red as oxygen, blue as nitrogen, yellow as sulfur) occupying the chemically significant active site permitting tetrahedral coordination to Zn(II) and the histidine triad (His94, His96, His119). Hydrogen bonding is depicted as red dashed lines. Only residues located within 5Å radius of bound ligand are displayed as lines (except gate keepers-Thr199 and Glu106-as sticks) and labeled with sequence number.