2INQ:
reference: Neutron diffraction studies of Escherichia coli dihydrofolate reductase complexed with methotrexate., Bennett B, Langan P, Coates L, Mustyakimov M, Schoenborn B, Howell EE, Dealwis C, Proc Natl Acad Sci U S A. 2006 Dec 5;103(49):18493-8. Epub 2006 Nov 27. PMID: 17130456

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).