2GQV:
reference: High-resolution structure of a plasmid-encoded dihydrofolate reductase: pentagonal network of water molecules in the D2-symmetric active site., Narayana N, Acta Crystallogr D Biol Crystallogr. 2006 Jul;62(Pt 7):695-706. Epub 2006, Jun 20. PMID: 16790925

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