Manca de Nadra M C, Nadra Chaud C A, Pesce de Ruiz Holgado A, Oliver G
Biotechnol Appl Biochem. 1986 Feb;8(1):46-52.
Carbamate kinase has been prepared from Lactobacillus buchneri NCDO110. An approximately 91-fold increase in the specific activity of the enzyme was achieved. The purified extract exhibited a single band following polyacrylamide gel electrophoresis. The apparent molecular weight as determined by gel electrophoresis was about 97,000. The enzyme is stable for 2 weeks at -20 degrees C. Maximum enzymatic activity was observed at 30 degrees C and pH 5.4 in 0.1 M acetate buffer. L. buchneri carbamate kinase requires Mg2+ or Mn2+; its activity is higher with Mn2+. The activation energy of the reaction was 4078 cal mol-1 for the reaction with Mn2+ and 3059 cal mol-1 for the reaction with Mg2+. From a Dixon plot a pK value of 4.8 was calculated. The apparent Km values for ADP with Mg2+ or Mn2+ were 0.71 X 10(-3) and 1.17 X 10(-3) M, respectively, and the apparent Km values for carbamyl phosphate with Mg2+ or Mn2+ were 1.63 X 10(-3) and 1.53 X 10(-3) M, respectively. ATP and CTP acted as inhibitors of this reaction and the following values were obtained: Ki (ATP)Mg2+ = 9.4 mM, Ki (ATP)Mn2+ = 6.2 mM, and Ki (CTP)Mg2+ = 4.4 mM.
氨基甲酸酯激酶是从布氏乳杆菌NCDO110中制备的。该酶的比活性提高了约91倍。纯化后的提取物在聚丙烯酰胺凝胶电泳后呈现出一条带。通过凝胶电泳测定的表观分子量约为97,000。该酶在-20℃下可稳定保存2周。在0.1M乙酸盐缓冲液中，30℃和pH 5.4时观察到最大酶活性。布氏乳杆菌氨基甲酸酯激酶需要Mg2+或Mn2+；Mn2+存在时其活性更高。与Mn2+反应的反应活化能为4078 cal mol-1，与Mg2+反应的反应活化能为3059 cal mol-1。根据Dixon图计算出pK值为4.8。Mg2+或Mn2+存在时，ADP的表观Km值分别为0.71×10(-3)和1.17×10(-3)M，Mg2+或Mn2+存在时，氨甲酰磷酸的表观Km值分别为1.63×10(-3)和1.53×10(-3)M。ATP和CTP作为该反应的抑制剂，得到以下值：Ki(ATP)Mg2+ = 9.4 mM，Ki(ATP)Mn2+ = 6.2 mM，Ki(CTP)Mg2+ = 4.4 mM。
