Prolidases are peptidases that are specific for dipeptides with proline as the
second residue. The structure of recombinant prolidase from the
hyperthermophilic archaeon Thermococcus sibiricus (Tsprol) was determined at
2.6 Å resolution. The homodimer of Tsprol is characterized by a complete lack
of interactions between the N- and C-terminal domains of the two subunits and
hence can be considered to be the most open structure when compared with
previously structurally studied prolidases. This structure exists owing to
intermolecular coordination bonds between cadmium ions derived from the
crystallization solution and histidine residues of a His tag and aspartate and
glutamate residues, which link the dimers to each other. This linking leads to
the formation of a crystal with a loose packing of protein molecules and low
resistance to mechanical influence and temperature increase.
