3H9C:
reference: Switching from an induced-fit to a lock-and-key mechanism in an aminoacyl-tRNA synthetase with modified specificity., Schmitt E, Tanrikulu IC, Yoo TH, Panvert M, Tirrell DA, Mechulam Y, J Mol Biol. 2009 Dec 18;394(5):843-51. Epub 2009 Oct 23. PMID: 19837083

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