Rapid and sensitive single-step radiochemical assay for catechol-O-methyltransferase.

A simple, rapid and reliable radiometric assay for the determination of catechol-O-methyltransferase activity is described. The method is based on the conversion of catechol to [3H]guaiacol by catechol-O-methyltransferase in the presence of Mg2+, adenosine deaminase and S-adenosyl L-[methyl-3H]methionine. Incubation and direct extraction of [3H]guaiacol into organic scintillation fluid, as well as counting, are performed in the same standard scintillation vial. The assay is easy to perform and more sensitive than previous analogous procedures. The method has been applied to the assay of catechol-O-methyltransferase activity in discrete brain areas and also peripheral organs of rat and in human erythrocytes.