Prusiner S, Miller R E, Valentine R C
Proc Natl Acad Sci U S A. 1972 Oct;69(10):2922-6. doi: 10.1073/pnas.69.10.2922.
The effect of cAMP on the intracellular levels of five enzymes concerned with the interconversion of glutamate and glutamine in E. coli has been examined. Cyclic AMP added to the culture medium increases the levels of glutamate dehydrogenase (EC 1.4.1.4) and glutamine synthetase (EC 6.3.1.2); it decreases the levels of glutamate synthase (EC 1.4.1.X), and glutaminase A (EC 3.5.1.2). Cyclic AMP did not affect the level of glutaminase B (EC 3.5.1.2). These alterations in enzyme levels by cAMP require cyclic AMP receptor protein, since the levels of these enzymes were unchanged by cAMP in a mutant lacking this receptor. Chloramphenicol also abolished the effects of cAMP, a result that implies protein synthesis is necessary for these changes in enzyme levels to occur. The reciprocal effects of cAMP on the levels of these enzymes may play an important role in the cellular regulation of nitrogen metabolism.
已研究了环磷酸腺苷（cAMP）对大肠杆菌中与谷氨酸和谷氨酰胺相互转化有关的五种酶的细胞内水平的影响。添加到培养基中的环磷酸腺苷会增加谷氨酸脱氢酶（EC 1.4.1.4）和谷氨酰胺合成酶（EC 6.3.1.2）的水平；它会降低谷氨酸合酶（EC 1.4.1.X）和谷氨酰胺酶A（EC 3.5.1.2）的水平。环磷酸腺苷不影响谷氨酰胺酶B（EC 3.5.1.2）的水平。cAMP引起的这些酶水平的变化需要环磷酸腺苷受体蛋白，因为在缺乏该受体的突变体中，cAMP不会改变这些酶的水平。氯霉素也消除了cAMP的作用，这一结果表明蛋白质合成对于这些酶水平的变化发生是必要的。cAMP对这些酶水平的相反作用可能在细胞氮代谢调节中起重要作用。
