Use of monoclonal and polyclonal antibodies as structural and topographical probes for hepatic epoxide hydrolase

Monoclonal antibodies have been prepared against rat liver epoxide hydrolase (EH), some of which gave precipitation lines on immunodiffusion against pure EH suggesting the presence of repetitive structural domains on the enzyme. Using ELISA, with polyclonal antibodies to rat and rabbit liver EH, reactivity and therefore structural similarities between EH of all species tested, including human, were observed. This was in contrast to immunodiffusion results demonstrating the limitations of the latter technique. Using monoclonal antibodies in ELISA, greatest structural similarity was between rat, mouse, and Syrian hamster EH and relatively little between rat and human. Two of the antibodies reacted with nearly all species tested and may be directed towards critical sites on the enzyme. This and most of the EH molecule would appear to be localised on the cytoplasmic surface of the endoplasmic reticulum.