1FX1:
reference: The binding of riboflavin-5'-phosphate in a flavoprotein: flavodoxin at 2.0-Angstrom resolution., Watenpaugh KD, Sieker LC, Jensen LH, Proc Natl Acad Sci U S A. 1973 Dec;70(12):3857-60. PMID: 4521211

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