Does ornithine stimulate carbamoylphosphate synthetase?
The effect of ornithine on carbamoylphosphate formation of rat liver mitochondria treated with Triton X 100 was studied. The rate of carbamoylphosphate accumulation and citrulline formation depended on the ATP-, Pi-, N-acetylglutamate and protein concentration. At optimal conditions the rate of citrulline formation was at least 1.5-fold higher than the rate at which carbamoylphosphate accumulated (ornithine absent). A significant correlation between the amount of carbamoylphosphate formed and the citrulline/carbamoylphosphate ratio (ornithine effect) was found. In mitochondria the presence of a carbamoylphosphate degrading enzyme could be demonstrated. This enzyme may be one factor for the differences in the rate of carbamoylphosphate accumulation and the rate of citrulline synthesis.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000378:metabolism*; D002221:Carbamyl Phosphate / Q000096:biosynthesis; D002956:Citrulline / Q000096:biosynthesis; D005971:Glutamates / Q000494:pharmacology; D007700:Kinetics; D008025:Ligases / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D017830:Octoxynol; D009952:Ornithine / Q000494:pharmacology*; D010710:Phosphates / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D011506:Proteins / Q000494:pharmacology; D051381:Rats
D005971:Glutamates; D010710:Phosphates; D011506:Proteins; D002956:Citrulline; D011092:Polyethylene Glycols; D002221:Carbamyl Phosphate; D000255:Adenosine Triphosphate; D017830:Octoxynol; D009952:Ornithine; D008025:Ligases; D002222:Carbamoyl-Phosphate Synthase (Ammonia); C016195:N-acetylglutamic acid