García-Olalla C, Barrio J P, Garrido-Pertierra A
Rev Esp Fisiol. 1982 Dec;38(4):409-17.
Pyruvate kinase, activated by fructose-1,6-biphosphate from Salmonella typhimurium LT-2, has been isolated and purified to homogeneity. The enzyme, similar to that from Escherichia coli, is a tetramer with an approximate molecular weight of 240,000. The native enzyme shows optimum pH 6.8 (T = 30 degrees C). The enzymatic reaction does not require K+ ions; while Mg2+ or Mn2+ are essential for its activity. The non-activated enzyme shows sigmoid kinetics to phosphoenolpyruvate with a Hill coefficient of 2.73; the activated enzyme becomes michaelian with KSADP y KSPEP 0.25 and 0.08 mM, respectively. Both substrates excess and ATP cause enzyme inhibition. In agreement with the experimental results a steady-state random-ordered hybrid Bi-Bi mechanism with two dead-end complexes is proposed.
已从鼠伤寒沙门氏菌LT-2中分离并纯化出由1,6-二磷酸果糖激活的丙酮酸激酶，且达到了均一性。该酶与大肠杆菌中的酶相似，是一种四聚体，分子量约为240,000。天然酶在30℃时的最适pH为6.8。酶促反应不需要K⁺离子；而Mg²⁺或Mn²⁺对其活性至关重要。未激活的酶对磷酸烯醇丙酮酸呈现S形动力学，希尔系数为2.73；激活后的酶对ADP和磷酸烯醇丙酮酸的米氏常数分别为0.25 mM和0.08 mM，呈现米氏动力学。底物过量和ATP均会导致酶抑制。与实验结果一致，提出了一种具有两个终产物复合物的稳态随机有序混合双底物双产物机制。
