3A4K:
reference: Structures of restriction endonuclease HindIII in complex with its cognate DNA and divalent cations., Watanabe N, Takasaki Y, Sato C, Ando S, Tanaka I, Acta Crystallogr D Biol Crystallogr. 2009 Dec;65(Pt 12):1326-33. doi:, 10.1107/S0907444909041134. Epub 2009 Nov 17. PMID: 19966419

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