4B2K:
reference: Directed Manipulation of a Flavoprotein Photocycle., Staudt H, Hoesl MG, Dreuw A, Serdjukow S, Oesterhelt D, Budisa N, Wachtveitl J, Grininger M, Angew Chem Int Ed Engl. 2013 Jul 1. doi: 10.1002/anie.201302334. PMID: 23818044

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