The PI proposes to continue studies of the structure, evolution, and function of cephalopod hemocyanins with limited extension of recent work on Octopus hemocyanin and major new projects involving the hemocyanins of Nautilus and of the squid Loligo. Initially, certain ongoing studies of Octopus hemocyanin will be brought to completion. These include experiments utilizing cleaved subunits as tools in exploration of functional behavior. A detailed analysis of the subunit structure of the Nautilus and Loligo hemocyanins will be undertaken, to provide the kind of complete structural picture the PI has developed for Octopus. The number of kinds of polypeptide chains involved in each case, and the number of functional units in each chain will be determined. The roles of multiple chain types in assembly will be assessed. Limited peptide sequencing will be carried out in order to allow alignment of the Loligo and Nautilus units with those of Octopus and with those in gastropod hemocyanins. If time and funds permit, a re-examination of the oxygen-binding function and allostery of Loligo hemocyanin is proposed, since early studies indicated a remarkable oxygen-linked dissociation process. This slow process should allow the first kinetic studies on a hemocyanin dissociation reaction.
