| Popis: |
Publisher Summary This chapter discusses the concepts of the regulation of branched and converging pathways. The chapter discusses functional classification of pathways and levels of their regulation. From a physiological standpoint, the various pathways of intermediary metabolism may be classified into three major categories: (1) biosynthetic, (2) catabolic, and (3) amphibolic. This functional categorization of pathways serves to focus attention on the means by which regulation of these routes is accomplished. Because a majority of biosynthetic routes are repressible, the impression has gained ground that induction as a genetic control mechanism is not of any great consequence in strictly biosynthetic pathways. In Pseudomonas putida , the last two enzymes of the tryptophan biosynthetic pathway—tryptophan synthetase A and B—are inducible by indole glycerol phosphate, the product of the first feedback sensitive enzyme of the pathway, anthranilate synthetase. It is well-known that in another bacterium, E. coli , these same enzymes are repressible by tryptophan. |
