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Hexamers of subunit II from Limulus hemocyanin (a 48‐mer) have the same quaternary structure as whole Panulirus hemocyanin molecules
Author(s) -
Magnus Karen A.,
Lattman Eaton E.,
Volbeda Anne,
Hol Wim G. J.
Publication year - 1991
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340090403
Subject(s) - hemocyanin , limulus , protein quaternary structure , protein subunit , random hexamer , crystallography , horseshoe crab , biology , chemistry , biochemistry , evolutionary biology , paleontology , genetics , antigen , gene
Hemocyanins are copper‐containing proteins that transport oxygen in a variety of invertebrates. Considerable evidence has accumulated that arthropodan hemocyanins are multimers of a fundamental hexameric unit. X‐Ray crystallographic structure determination has revealed that the hemocyanin molecule from the spiny lobster Panulirus interruptus is a single hexamer having 32 point group symmetry. Using crystals of subunit II, one of 8 polypeptide types comprising the octahexameric hemocyanin of the horseshoe crab Limulus polyphemus , and the molecular replacement method for crystallographic phase determination we show that subunit II forms assemblies with the same hexameric quaternary structure as the whole Panulirus hemocyanin molecule. Observation of the same hexameric motif in two widely separated species provides strong additional evidence that this quaternary structural unit is a universal building block of arthropodan hemocyanins.