The reduction of (203)Hg(++) by (L)-ascorbic acid, (DL)-α-tocopherol, superoxide anion and the supernatant of mouse liver homogenate after the ultracentrifugation were performed. The results obtained were as follows. 1. The relationships between the reductive rate of mercuric ion and the concentration of the (L)-AsA or (DL)-α-tocopherol were shown as a sigmoidal curve; that of the superoxide anion was a linear. 2. The activity of reduction of Hg(++) was in decreasing order with (L)-AsA, (DL)-α-tocopherol, and superoxide anion, respectively. 3. The liver homogenate was used with 8.5% sucrose and 11% polyvinylpirrolidone (PVP) solution with preparation of the homogenate to prevent release of catalase from the peroxisomes. Another preparation used 44mM phosphate buffer (pH 6.8) solution and the liver catalase was released from peroxisomes. The reductive rate of mercuric ion with the former preparation was 6.4 times higher than with the latter. It indicates that the reoxidation of metallic mercury by the catalase reduced the reductive rate of mercuric ion. 4. A reductive experiment of mercuric ion by liver supernatant containing sucrose and PVP at 0°C and 37°C was performed. The reduction rate by this sample at 0°C is 1/5.48 of that at 37° C. This suggests that the reduction of mercuric ion in liver homogenate is due to an enzymatic reaction.
reduction of mercuric ion