Integration of Pathways of Synthesis and Degradation of Hexose Phosphates

Publisher Summary This chapter discusses the integration of pathways of synthesis and degradation of hexose phosphates. In higher plants, hexose phosphates are formed in photosynthesis and gluconeogenesis, and also from the breakdown of storage carbohydrates; they are consumed by glycolysis and the oxidative pentose phosphate pathway, and also in the synthesis of oligo- and polysaccharides. Thus, hexose phosphates play a dominant role in carbohydrate metabolism and consequently, in the economy of the plant as a whole. The reductive and oxidative pentose phosphate pathways, glycolysis, and gluconeogenesis share other intermediates in addition to hexose phosphates. In the studies of the control of hexose phosphate metabolism, the evidence strongly indicates that most of the control is exercised by the selected regulatory enzymes. Such enzymes are regarded as those which respond to the original metabolic signal and which initiate changes in the activities of the remaining enzymes of the pathways.