5E4R:
reference: Artificial domain duplication replicates evolutionary history of ketol-acid reductoisomerases., Cahn JK, Brinkmann-Chen S, Buller AR, Arnold FH, Protein Sci. 2015 Dec 8. doi: 10.1002/pro.2852. PMID: 26644020

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