Immunochemical demonstration of increased accumulation of ornithine carboxylase in rat liver after partial hepatectomy and growth hormone induction.

Antiserum against ornithine decarboxylase (EC 4.1.1.17) was prepared in rabbits using purified ornithine decarboxylase from rat liver as the antigen. Immunoglobulins from the immune sera were covalently coupled to agarose by cyanogen bromide activation. With the aid of this immunoadsorbent against the enzyme it has been shown that following partial hepatectomy and growth hormone administration, the ornithine decarboxylase activity is elevated concomitantly with the increase in the immunoreactive enzyme protein. In addition, the rapid decay in ornithine decarboxylase activity in regenerating rat liver after cycloheximide injection is accompanied by a decrease in the immunoreactive protein. These results suggest that the activity of ornithine decarboxylase in rat liver is regulated through rapid changes in de novo synthesis and degradation of the enzyme protein.