Acetylation of procainamide and isoniazid by a rat liver-N-acetyl-transferase.

The genetic variation of the enzyme isoniazid-N-acetyltransferase has been studied in man and other species. Homogenates of liver samples of adult LEW rats also acetylate procainamide. The kinetic properties of isoniazid and procainamide acetylation are similar and are consistent with a ping-pong Bi-Bi mechanism. The experimental data support the hypothesis that one acetyltransferase catalyses both procainamide and isoniazid. Furthermore, a simple spectrophotometric assay to determine procainamide acetylation is presented.