Properties of the mercury and selenium complex formed in rat plasma in vivo

Properties of the mercury and selenium complex (Hg-Se Complex) produced in plasma after the simultaneous injection of mercuric chloride and sodium selenite were investigated by means of pronase digestion and isoelectric focusing. When the gel chromatographic fraction containing the HG-Se complex was digested with Pronase E and chromatographed on a Sephadex G-200 column, the resulting derived proteins contained no mercury and very low percentage of selenium. Most of mercury and selenium in the digest of the Hg-Se complex remained at the top of column, but the content of proteins (derived proteins) found at the same site of column was only trace amount. In contrast, the derived proteins obtained from proteins containing mercury or selenium in serum by the same digestion contained mercury and high percentage of selenium respectively. These results indicated that the Hg-Se complex in plasma did not contain protein as a component. When the isoelectric focusing of the serum containing the Hg-Se complex was carried out, the peak containing both mercury and selenium was present in the position of pH2 and pH4. The former peak was independent of the serum proteins, the latter peak overlapped the distribution of that. Similar behavior of mercury and selenium was observed in the isoelectric focusing of the mercuric selenide colloid dispersed in the solution containing bovine serum albumin. The properties of the Hg-Se complex in these studies supported the hypothesis that it is a mercuric selenide colloid.