RESUMO
delta-(L-alpha-aminoadipyl)-L-cysteine synthetase (LL-AC synthetase) activity has been found in extracts of Cephalosporium acremonium C-10. The enzyme extract carries out a linear synthesis of LL-AC from its constituent amino acids for at least 6 hours. The reaction is dependent on active enzyme, time, L-alpha-aminoadipate, L-cysteine, ATP and Mn2+ or Mg2+. The activity is stabilized by glycerol.
Assuntos
Acremonium/metabolismo , Cefalosporinas/biossíntese , Dipeptídeos/biossíntese , Penicilinas/biossíntese , Trifosfato de Adenosina/metabolismo , Sistema Livre de Células , Cromatografia Líquida de Alta Pressão , Cinética , Magnésio/metabolismo , Manganês/metabolismo , TemperaturaRESUMO
The effect of glucagon and the protein content of the diet on the activity of N-acetylglutamate synthetase was studied. The activity of N-acetylglutamate synthetase depended on the protein content of the diet. Glucagon increased the activity of N-acetylglutamate synthetase and reduced the stimulatory effect of arginine. The enzyme of glucose-fed animals became arginine independent. It was concluded that glucagon induced some kind of covalent modification of the synthetase.
Assuntos
Acetiltransferases/metabolismo , Glucagon/farmacologia , Mitocôndrias Hepáticas/enzimologia , Aminoácido N-Acetiltransferase , Animais , Glicemia/metabolismo , Proteínas Alimentares/farmacologia , Cinética , Masculino , Ratos , Ratos Endogâmicos , Partículas Submitocôndricas/enzimologiaRESUMO
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.