The long term aim of this project is to determine at atomic resolution the three dimensional structures of various forms of hemocyanin, an oxygen transport protein found in invertebrates, with the intent of understanding the intricacies of oxygen binding by these copper-containing proteins. The specific objectives are: (1) the determination of the crystal structure of the oxygenated and deoxygenated forms of subunit II of Limulus polyphemus hemocyanin; (2) Comparison of the oxy and deoxy structures, based on data from a single crystal if necessary, for the elucidation of the active site geometry, including the orientation of the molecular oxygen with respect to the two copper centers and protein ligands; and (3) The crystallization of other interesting hemocyanins, such as subunit IIIa, another subunit of Limulus hemocyanin with an active site chemistry much more like a typical molluscan than arthropodan hemocyanin, the whole molecules of Limulus hemocyanin and hybrid and cooperative Limulus hexamers in forms suitable for x-ray diffraction analysis.
