A method is described for measuring the rate of phosphoenolpyruvate-dependent phosphotransferase activity for a variety of hexoses in toluene-treated suspensions of Escherichia coli. 2. The specific activities of the phosphotransferases that catalyse the phosphorylation of hexoses are greatly affected by the carbon source for growth. 3. In all strains of E. coli tested, fructose phosphotransferase activity is induced by growth on fructose. 4. Strains of E. coli differ greatly in the rate at which they phosphorylate glucose, but all strains possess at least a low glucose phosphotransferase activity under any tested condition of growth. Glucose phosphotransferase activity is further induced by growth on glucose; this does not occur in a mutant that lacks the ability to take up methyl alpha-d-[(14)C]glucopyranoside and hence grows poorly on glucose. 5. When growing on fructose, two strains of E. coli synthesize the inducible glucose phosphotransferase system gratuitously, and to specific activities higher than observed during growth on glucose. A phosphotransferase catalysing the phosphorylation of mannose is similarly induced.
摘要
本文描述了一种用于测定经甲苯处理的大肠杆菌悬浮液中多种己糖的磷酸烯醇丙酮酸依赖性磷酸转移酶活性速率的方法。2. 催化己糖磷酸化的磷酸转移酶的比活性受生长碳源的极大影响。3. 在所有测试的大肠杆菌菌株中，果糖磷酸转移酶活性由在果糖上生长诱导产生。4. 大肠杆菌菌株在磷酸化葡萄糖的速率上差异很大，但在任何测试的生长条件下，所有菌株都至少具有低水平的葡萄糖磷酸转移酶活性。葡萄糖磷酸转移酶活性通过在葡萄糖上生长进一步诱导产生；在缺乏摄取α - d - [(14)C]葡萄糖吡喃糖苷能力因而在葡萄糖上生长不良的突变体中不会发生这种情况。5. 当在果糖上生长时，两株大肠杆菌会免费合成可诱导的葡萄糖磷酸转移酶系统，且其比活性高于在葡萄糖上生长时观察到的比活性。催化甘露糖磷酸化的磷酸转移酶也以类似方式被诱导。
