1QPA:
reference: The crystal structure of lignin peroxidase at 1.70 A resolution reveals a hydroxy group on the cbeta of tryptophan 171: a novel radical site formed during the redox cycle., Choinowski T, Blodig W, Winterhalter KH, Piontek K, J Mol Biol 1999 Feb 26;286(3):809-27. PMID: 10024453

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