Hemocyanin from Palinurus elephas: general properties and effects of heavy metals

The structural and functional properties of hemocyanin from the lobster Palinurus elephas indicate that this protein is similar to that of Panulirus interruptus, as expected on the basis of the phylogenetic relatedness of the two species. The process of (re)association of subunits into hexamers has been studied by ultracentrifuge and stopped-flow techniques; complete reassociation requires both neutral pH and presence of calcium ions and appears to be a relatively fast process (time-scale of 1 min). The effect of three heavy metals (Hg, Cd and Cr) on the structural and functional properties of this protein has been investigated in order to ascertain whether hemocyanin may be a target of metal poisoning. At low concentrations the three metals are effective in modifying (reversibly) the functional properties of the protein, although each metal induces different modifications. Very high concentrations of Cr and Hg, and long incubation times result in the removal of copper from the active site, while Cd seems unable to do so.