Hemocyanin from the Australian freshwater crayfish Cherax destructor. Characterization of a dimeric subunit and its involvement in the formation of the 25S component
The MW of a dimeric subunit, M3'', isolated from C. destructor hemocyanin was measured by sedimentation equilibrium to be 144,000. Peptide mapping and end-group analysis together with gel electrophoresis showed that the dimer consisted of 2 very similar or identical monomers, cross-linked by disulfide bridges. Dissociation of the 25S component of the hemocyanin showed that it contained the dimer and 2 previously identified monomers, M1 and M2. Its MW was 900,000 by sedimentation equilibrium,and reconstitution studies showed that the dimer was essential for its formation. Analysis of polyacrylamide disc gel electrophoresis results with the 25S component indicated that it consisted of a population of 11 compositional isomers. These all contained 1 dimeric subunit and 10 monomeric subunits, the latter being present in all the combinations of M1 and M2.