4J0L:
reference: Complete subsite mapping of a "loopful" GH19 chitinase from rye seeds based on its crystal structure., Ohnuma T, Umemoto N, Kondo K, Numata T, Fukamizo T, FEBS Lett. 2013 Aug 19;587(16):2691-7. doi: 10.1016/j.febslet.2013.07.008. Epub, 2013 Jul 18. PMID: 23871710

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