1U0D:
reference: Isolation and characterization of new homing endonuclease specificities at individual target site positions., Sussman D, Chadsey M, Fauce S, Engel A, Bruett A, Monnat R Jr, Stoddard BL, Seligman LM, J Mol Biol 2004 Sep 3;342(1):31-41. PMID: 15313605

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