Determination of Ornithine Decarboxylase Activity Using [3H]Omithine

Ornithine decarboxylase (EC 4.1.1.17) (ODC) catalyzes the decarboxylation of ornithine to form putrescine. This reaction is the rate-limiting step in the biosynthesis of the naturally occurring polyamines, which regulate proliferation and which are closely linked to neoplastic growth. Because of the central role played by ODC in various biological systems, attempts have been made to develop sensitive, specific, and simple methods for its assay. These methods can be divided into three categories: assay of ODC mRNA; assay of ODC protein; and assay of ODC activity.