1NOL:
reference: Crystal structure of deoxygenated Limulus polyphemus subunit II hemocyanin at 2.18 A resolution: clues for a mechanism for allosteric regulation., Hazes B, Magnus KA, Bonaventura C, Bonaventura J, Dauter Z, Kalk KH, Hol WG, Protein Sci 1993 Apr;2(4):597-619. PMID: 8518732

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