A new crystal form of the R163K variant of human thymidylate synthase (hTS) with five subunits per asymmetric part of the unit cell, all with loop 181-197 in the active conformation, is reported.

The structure of a complex of sperm whale myoglobin with phenol places this inhibitor of the haloperoxidase activity in a proximal cavity that is unlikely to be the halophenol binding site. The absence of phenol binding at the heme edge, where dehalogenation is likely to take place, indicates that the inhibitor and the halophenol substrates only bind in the active site in the presence of hydrogen peroxide.