2I9K:
reference: Engineered extrahelical base destabilization enhances sequence discrimination of DNA methyltransferase M.HhaI., Youngblood B, Shieh FK, De Los Rios S, Perona JJ, Reich NO, J Mol Biol. 2006 Sep 15;362(2):334-46. Epub 2006 Jul 21. PMID: 16919299

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