Partial purification and properties of carbamoyl phosphate synthetase of Alaska pea (Pisum sativum L. cultivar Alaska).
1. Carbamoyl phosphate synthetase was purified up to 45-fold from Alaska pea seedling (Pisum sativum L. cultivar Alaska). 2. The enzyme was most active with and had the lowest K(m) for l-glutamine as compared with NH(4) (+). 3. The purest preparations utilized very poorly or not at all l-asparagine and urea as nitrogen donors. 4. At saturating concentrations of components of the reaction, the K(m) for l-glutamine was 1.2x10(-4)m, and the K(m) for ATP was approx. 3.9x10(-4)m. 5. Although the enzyme was very labile, stability was improved by glutamine, asparagine, ammonium sulphate, dithiothreitol and especially l-ornithine. 6. Free ATP was markedly inhibitory, and MgATP(2-) and Mg(2+) appeared to be the actual substrates utilized. 7. Fe(2+) and Mn(2+) were also utilized, but not as readily as Mg(2+) except at low concentrations. K(+) increased activity significantly. 8. Of the four nucleotides tested (ITP, ATP, GTP and UTP) only ATP served as an effective phosphate donor.
D000255:Adenosine Triphosphate; D001216:Asparagine; D002219:Carbamates; D002850:Chromatography, Gel; D005973:Glutamine; D007501:Iron; D008274:Magnesium; D008345:Manganese; D009952:Ornithine; D010770:Phosphotransferases / Q000302:isolation & purification*; D010944:Plants / Q000201:enzymology*; D011188:Potassium; D000644:Quaternary Ammonium Compounds; D014508:Urea
D002219:Carbamates; D000644:Quaternary Ammonium Compounds; D005973:Glutamine; D008345:Manganese; D001216:Asparagine; D000255:Adenosine Triphosphate; D014508:Urea; D007501:Iron; D009952:Ornithine; D010770:Phosphotransferases; D008274:Magnesium; D011188:Potassium