CRYSTALS OF THE CARBOXYL-TERMINAL FUNCTIONAL UNIT FROM OCTOPUS-DOFLEINI HEMOCYANIN

The carboxyl-terminal oxygen-binding unit of the polypeptide from Octopus dofleini hemocyanin has been crystallized in a form suitable for three-dimensional X-ray analysis. This proteolytic fragment has a molecular weight of 47 kDa and reversibly binds O2 while exhibiting a slight Bohr effect. Two types of crystals have been grown. Type 1 crystals, currently under analysis, belong to the orthorhombic space group P212121 and have unit cell dimensions of 92·6 Å × 167·4 Å × 59·2 Å. A composition of two protein molecules per asymmetric unit and 50% solvent content is consistent with a self-rotation function that identifies a non-crystallographic 2-fold axis of symmetry relating these molecules. Diffraction extending beyond 1·9 Å Bragg spacings can be detected with synchrotron X-radiation. © 1990 Academic Press Limited.