Purification of human hepatic glutathione S-transferases and the development of a radioimmunoassay for their measurement in plasma.
A purification scheme is described for six human hepatic glutathione S-transferases from a single liver. Five of the transferases comprised Ya monomers and had a molecular mass of 44 000. The remaining enzyme comprised Yb monomers and had a molecular mass of 47 000. Data are presented demonstrating that there are at least two distinct Ya monomers. A radioimmunoassay has been developed that has sufficient precision and sensitivity to allow direct measurement of glutathione S-transferase concentrations in unextracted plasma. A comparison of aminotransferase and glutathione S-transferase levels, in three patients who had taken a paracetamol overdose, indicated that glutathione S-transferase measurements provided a far more sensitive index of hepatocellular integrity than the more conventional aminotransferase measurements.