Crystallographic analysis of oxygenated and deoxygenated states of arthropod hemocyanin shows unusual differences.

Published

Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Magnus, KA; Hazes, B; Ton-That, H; Bonaventura, C; Bonaventura, J; Hol, WG

Published Date

  • August 1994

Published In

Volume / Issue

  • 19 / 4

Start / End Page

  • 302 - 309

PubMed ID

  • 7984626

Pubmed Central ID

  • 7984626

Electronic International Standard Serial Number (EISSN)

  • 1097-0134

International Standard Serial Number (ISSN)

  • 0887-3585

Digital Object Identifier (DOI)

  • 10.1002/prot.340190405

Language

  • eng