Some biochemical properties of the preneoplastic antigen in rat liver hyperplastic nodules.

The biochemical properties of preneoplastic antigen (PN antigen) were investigated in order to resolve inconsistencies in previous reports. First of all, epoxide hydrase was purified biochemically from the liver of phenobarbital-treated rats and anti epoxide hydrase serum was prepared in rabbits. Immunochemically, in Ouchterlony double diffusion, PN antigen had the same antigenicity as epoxide hydrase. From an immunoprecipitation study using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and crossed immunoelectrophoresis, it was found that PN antigen may be composed of epoxide hydrase and at least one more protein (mol. wt. 27,000). However, the biochemical and biological properties of the protein binding to epoxide hydrase were not determined. The existence of PN antigen (epoxide hydrase and its binding protein) may be associated with microsomal membrane alterations during chemical carcinogenesis.