Arginine activation of N-acetylglutamate synthetase in mouse liver. Enhancement of the sensitivity in vivo by parenteral treatment with inhibitors of nucleic acid and protein synthesis.

N-Acetyl-L-glutamate synthetase catalyzes the synthesis of N-acetyl-L-glutamate, an allosteric and essential activator of carbamoyl-phosphate synthetase I in the liver of ureotelic animals. The enzyme is activated specifically by arginine. We report here that the sensitivity of the synthetase to activation by arginine increases markedly after intraperitoneal administration to mice of inhibitors of nucleic acid and protein synthesis, including actinomycin D, aurintricarboxylic acid, cycloheximide, emetine and puromycin. The effects of cycloheximide were investigated in detail and an amino acid analysis was made of the homogenate of freeze-clamped livers of control or cycloheximide-treated mice.