Dear Bazai,

There are two classes of aromatase inhibitors (AIs): (i) steroidal and (ii) non-steroidal. Steroidal AIs are known as mechanism-based inhibitors as they bind irreversibly to the binding pocket of aromatase as they are converted to a chemically reactive specie. It should be noted that steroidal AIs do not bind the heme group. Non-Steroidal AIs bind reversibly via coordinating its azole nitrogen atom to the iron atom of the heme prosthetic group.

Our docking results revealed that AIs bind snugly within the protein cavity surrounded by hydrophobic residues. In summary, polar (D309, T310, S478 and M374), aromatic (F134, F221 and W224) and non-polar (A306, A307, V370, L372 and L477) residues were important for interacting with the AIs [see reference below].

http://dx.doi.org/10.3390/molecules16053597