Crystallographic analysis of oxygenated and deoxygenated states of arthropod hemocyanin shows unusual differences.Magnus, K.A., Hazes, B., Ton-That, H., Bonaventura, C., Bonaventura, J., Hol, W.G.
(1994) Proteins 19: 302-309
- PubMed: 7984626
- DOI: 10.1002/prot.340190405
- PubMed Abstract:
- Hexamers of Subunit II from Limulus Hemocyanin (A 48mer) Have the Same Quaternary Structure as Whole Panulirus Hemocyanin Molecules
Magnus, K.A.,Lattman, E.E.,Volbeda, A.,Hol, W.G.L.
(1991) Proteins 9: 240
- Crystals of a Functional 70,000 Molecular Weight Subunit of Hemocyanin from Limulus Polyphemus
Magnus, K.A.,Love, W.E.
(1977) J.Mol.Biol. 116: 171
The X-ray structure of an oxygenated hemocyanin molecule, subunit II of Limulus polyphemus hemocyanin, was determined at 2.4 A resolution and refined to a crystallographic R-factor of 17.1%. The 73-kDa subunit crystallizes with the symmetry of the sp ...
The X-ray structure of an oxygenated hemocyanin molecule, subunit II of Limulus polyphemus hemocyanin, was determined at 2.4 A resolution and refined to a crystallographic R-factor of 17.1%. The 73-kDa subunit crystallizes with the symmetry of the space group R32 with one subunit per asymmetric unit forming hexamers with 32 point group symmetry. Molecular oxygen is bound to a dinuclear copper center in the protein's second domain, symmetrically between and equidistant from the two copper atoms. The copper-copper distance in oxygenated Limulus hemocyanin is 3.6 +/- 0.2 A, which is surprisingly 1 A less than that seen previously in deoxygenated Limulus polyphemus subunit II hemocyanin (Hazes et al., Protein Sci. 2:597, 1993). Away from the oxygen binding sites, the tertiary and quaternary structures of oxygenated and deoxygenated Limulus subunit II hemocyanins are quite similar. A major difference in tertiary structures is seen, however, when the Limulus structures are compared with deoxygenated Panulirus interruptus hemocyanin (Volbeda, A., Hol, W.G.J.J. Mol. Biol. 209:249, 1989) where the position of domain 1 is rotated by 8 degrees with respect to domains 2 and 3. We postulate this rotation plays an important role in cooperativity and regulation of oxygen affinity in all arthropod hemocyanins.
Department of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106-4935.