The binding pose of compound 3 is quite different from all the other studied compounds. The carboxylic group attached to carbon 2 of the psoralen was found to interact directly with the iron of the heme group (1.43 Å) and to establish two hydrogen bonds with Gly301 and Thr275 (2.43 Å and 2.39 Å). The remaining part of the psoralen structure is pointing towards the Asn297, but is too far to interact with it (4.79 Å), contrasting to what was observed for the other compounds.