High-quality crystals of human haematopoietic prostaglandin D synthase with novel inhibitors

Human haematopoietic prostaglandin D synthase (H‐PGDS; EC 5.3.99.2) produces prostaglandin D2, an allergic and inflammatory mediator, in mast cells and Th2 cells. H‐PGDS has been crystallized with novel inhibitors with half‐maximal inhibitory concentrations (IC50) in the low nanomolar range by the counter‐diffusion method onboard the Russian Service Module on the International Space Station. The X‐ray diffraction of a microgravity‐grown crystal of H‐PGDS complexed with an inhibitor with an IC50 value of 50 nM extended to 1.1 Å resolution at 100 K using SPring‐8 synchrotron radiation, which is one of the highest resolutions obtained to date for this protein.