1YI8:
reference: Structure and activity of an aminoacyl-tRNA synthetase that charges tRNA with nitro-tryptophan., Buddha MR, Crane BR, Nat Struct Mol Biol 2005 Mar;12(3):274-5. Epub 2005 Feb 20. PMID: 15723076

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