5C12:
reference: Two distinct modes of metal ion binding in the nuclease active site of a viral DNA-packaging terminase: insight into the two-metal-ion catalytic mechanism., Zhao H, Lin Z, Lynn AY, Varnado B, Beutler JA, Murelli RP, Le Grice SF, Tang L, Nucleic Acids Res. 2015 Oct 7. pii: gkv1018. PMID: 26450964

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