A method for covalent insertion of mercury into the cysteine disulfide bridges of proteins

A method is described by which atomic mercury can be taken up by thiol groups and inserted into the disulfide bridges of proteins which can be reversibly reduced and denatured. The method utilizes tandem columns of Sephadex G-10 and Biogel P2. Protein samples are separated from reducing and denaturing agent on the Sephadex column and then react with mercury, which is bound to the Biogel P2 column. Of eight proteins tested, all took up mercury using this method. The amount of mercury incorporated by this method differed from that found using other methods and was closer to the stoichiometry of the disulfide bridges of the protein than these methods.