Binding of radioactive α-difluoromethylorithine to rat liver ornithine decarboxylase

M. Lynn Pritchard, James E. Seely, Hannu Pösö, Leonard "Jim" Jefferson, Anthony Pegg

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Inactivation of rat liver ornithine decarboxylase by incubation with [5-14C]-α-difluoromethylornithine resulted in the covalent binding of radio-activity to the enzyme. The extent of binding correlated with the degree of inactivation and with the amount of enzyme present. The labeled protein eluted as a single peak which coincided exactly with the active enzyme when chromatographed on Sephadex G-200 and ran as a single band on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate at a position corresponding to a M.W. of about 55,000. The stoichiometric binding of [5-14C]-α-difluoromethylornithine therefore provides a convenient method for quantitating ornithine decarboxylase protein and for determining the purity of preparations of the enzyme. Assuming that 1 molecule of the drug is needed to inactivate each sub-unit, it was calculated that after stimulation with thioacetamide ornithine decarboxylase represents about 0.00014% of the liver soluble protein.

Original languageEnglish (US)
Pages (from-to)1597-1603
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number4
StatePublished - Jun 30 1981

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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