3IWM:
reference: Three-dimensional domain swapping as a mechanism to lock the active conformation in a super-active octamer of SARS-CoV main protease., Zhang S, Zhong N, Xue F, Kang X, Ren X, Chen J, Jin C, Lou Z, Xia B, Protein Cell. 2010 Apr;1(4):371-83. Epub 2010 May 8. PMID: 21203949

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