1LWS:
reference: Crystal structure of the intein homing endonuclease PI-SceI bound to its recognition sequence., Moure CM, Gimble FS, Quiocho FA, Nat Struct Biol 2002 Oct;9(10):764-70. PMID: 12219083

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