1VSD:
reference: The catalytic domain of avian sarcoma virus integrase: conformation of the active-site residues in the presence of divalent cations., Bujacz G, Jaskolski M, Alexandratos J, Wlodawer A, Merkel G, Katz RA, Skalka AM, Structure 1996 Jan 15;4(1):89-96. PMID: 8805516

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