Isolation and characterization of monoclonal antibodies against rat liver epoxide hydrolase

We have established hybridoma cell lines which secrete monoclonal antibody to rat liver microsomal epoxide hydrolase. All of the monoclonal antibodies formed against epoxide hydrolase are mouse immunoglobulin subclass IgG1. Utilizing double immunodiffusion analysis, we have found that the monoclonal antibodies bind to and precipitate epoxide hydrolase in solubilized rat liver microsomes. Despite the ability of the monoclonal antibodies to precipitate rat liver microsomal epoxide hydrolase, they do not inhibit the catalytic activity of the enzyme but rather stimulate it. The monoclonal antibodies do not precipitate epoxide hydrolase in microsomes isolated from hamster, rabbit, monkey, or human. When rabbit reticulocyte lysates are programmed with rat liver mRNA, the primary translation product of epoxide hydrolase can be immunoprecipitated from the translation system using the monoclonal antibodies. The ability of the antibodies to recognize in vitro synthesized epoxide hydrolase should make them amenable to identify recombinant bacterial clones expressing this protein. The monoclonality of these antibodies and their specificity should provide a useful way of identifying, purifying, and quantitating rat liver epoxide hydrolase as well as examine the expression of the gene(s) encoding epoxide hydrolase in normal rats and in rats exposed to carcinogenic xenobiotics.