Glucose-6-phosphate resynthesis

Describe the role of P-fructose-2,6-bisphosphate in the control of the further breakdown and resynthesis of glucose 1-phosphate. 

Summary of the pentose phosphate pathway. This diagram is intended to show the two major parts of the pathway oxidation and decarboxylation of glucose-6-phosphate to ribulose 5-phosphate, and resynthesis of the former from the latter. The stoichiometry of the pathway is ignored. 

In the first step of this pathway, glucose-6-phosphate + NADP+ is converted to 6-phosphogluconate + NADPH + H+ and, in the second step, 6-phosogluconate + NADP+ is converted to ribulose-5-phosphate + NADPH + H+. These reactions are considered to be the oxidative arm of the pentose-phosphate pathway and are critical for producing much of the NADPH used in biosynthetic pathways. The remainder of the cycle (i.e., the nonoxidative portion) consists of converting 5-carbon phosphorylated sugars to 3-, 4-, 5-, and 7-carbon intermediates, finally achieving the resynthesis of hexose-6-phosphate and triose phosphate. Some of... 

On the basis of the n.m.r. spectra of the cell-wall D-mannans, and the base composition and sequence similarities of the deoxyribonucleic acids, no distinction could be made between strains of Candida utilis and Hansenula jadinii although differences could be detected between H. jadinii and H. petersonii The catabolic and anabolic transformation of D-glucose by a Candida species into cell wall D-glucan and D-mannan has been reported.Approximately 20-40% of the hexose of these cell wall polysaccharides has been derived from the resynthesis of hexoses via the pentose phosphate pathway. 

The phosphoglucomutase reaction involves continual utilization and resynthesis of the cofactor, but it cannot cause the net synthesis of glucose-1,6-diphosphate. Two mechanisms have been found to increase the amount of this cofactor in each case glucose-l-phosphate is the phosphate acceptor but the phosphate donors are different for the two enzymes involved. Glucose-l-phosphate kinase requires ATP to carry out the reaction ... 

Evidently at least 2 moles of energy-rich phosphate are required One for the formation of phosphoenolpyruvate, and the second for the reduction of 3-phospho-glycerate, which proceeds as a reversal of the glycolytic reaction (see above). The reversal of the breakdown must, of course, be endergonic. It has long been knovn that 20-30% of lactate is combusted completely in order to allow the resynthesis of glucose. 

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