Dissociation of Proteins into Sub-units by Succinylation: Hæmerythrin

Abstract

IN the course of investigation of the molecular weight of the marine oxygen-carrying pigment hæmerythrin (obtained from Golfingia gouldii), indications arose that the macromolecule of about 105,000 molecular weight might be constituted of several smaller units. A few sedimentation experiments in solutions of sodium dodecyl sulphate, following a suggestion of Schachman¹, did reveal sub-units, but complete dissociation could not be obtained and the presence of detergent created a number of difficulties in experimental procedure. Since the effectiveness of the detergent in splitting the macromolecule probably depends in part on the electrostatic repulsion produced by the large negative charge of the bound ions, it seemed worth while to examine the effect of the introduction of additional negative charges covalently linked to the macro-molecule. Reaction of protein with succinic anhydride^2,3 should replace each cationic ɛ-NH₃⁺ charge by an anionic carboxylate group. Since hæmerythrin contains about 80 lysine groups, complete succinylation would change the charge on the 105,000 molecular weight macromolecule at pH 7 by about 160 units.