LIMITED PROTEOLYSIS OF THE HEMOCYANIN OF THE GASTROPOD PILA-LEOPOLDVILLENSIS - ISOLATION AND CHARACTERIZATION OF THE FRAGMENTS

Limited proteolysis with trypsin and endoproteinase Glu-C of dimers of subunits of the haemocyanin of Pila leopoldvillensis revealed the presence of eight functional (dioxygen binding) units (a-h) per subunit (M(r) approximate to 435,000). Fragments a-c, d-g and (d-h)(2) (dimer of d-h) and the dimer of functional unit h (h(2)) were isolated and characterized (copper content, M(r), N- and C-terminus, crossed immunoelectrophoresis, absorption and circular dichroic spectra, carbohydrate composition). Functional unit h contains the association site between the two subunits in a dimer, When compared with the average values for a functional unit it, moreover, shows a higher M(r) (approximate to 65,000 vs approximate to 55,000) and a higher carbohydrate content (approximate to 5.5%, w/w, vs approximate to 3.5%).