Phosphogluconate dehydrogenase EC

Chain trace of sheep liver 6-phosphogluconatc dehydrogenase subunit based on the work of Adams and colleagues [71], The NADP + binding region is indicated. 

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Figure 6.4. Role of transketolase in the pentose phosphate pathway. Glucose 6-phosphate dehydrogenase, EC 1.1.1.49 phosphogluconate dehydrogenase, EC 1.1.1.44 rihulose-phosphate epimerase, EC 5.1.3.1 phosphorihose isomerase, EC 5.3.1,6 transketolase, EC 2.2.1.1 and transaldolase, EC 2.2.I.2.

In potentiometric enzyme electrodes lyases producing carbon dioxide or ammonia are used as terminal enzymes of sequences. In fact, the term enzyme sequence electrode was introduced on the occasion of the design of a potentiometric D-gluconate sensor containing gluconate kinase (EC 2.7.1.12) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) (Jensen and Rechnitz, 1979). The authors found that for such a sensor to function the optimal pH values of the enzymes and the transducer should be close to each other. Furthermore, cofactors, if necessary, must not react with one another nor with constituents of the sample. It was concluded that the rate of substance conversion in multiple steps cannot exceed that of the terminal enzyme reaction. A linear concentration dependence is obtained when an excess of all enzymes of the sequence is provided, i.e. complete conversion occurs of all substrates within the enzyme membrane. Different permeabilities of the different substrates results in different sensitivities. This is particularly important with combinations of disaccharidases and oxidases, where the substrate is cleaved to two monosaccharides of approximately the same molecular size. The above... 

Phosphogluconate Dehydrogenase An enzyme of the oxidoreductase class that catalyzes the reaction 6-phospho-D-gluconate and NADP+ to yield D-ribulose 5-phosphate, carbon dioxide, and NADPH. The reaction is a step in the pentose phosphate pathway of glucose metabohsm. (From Borland, 27th ed) EC 1.1.1.43. [nih]... 

Polyhydroxyalkanoates biosynthesis is regulated, on one hand, by the activity of 3-ketothiolase (EC 2.3.1.16), and on the other hand of acetoacetyl-CoA reductase (EC 1.1.1.36) intracellular PHA breakdown is dependent on the activity of 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30). Besides these three enzymes, the following compounds can be pointed out as major factors responsible of the activities of the key enzymes acetyl-CoA, free CoA, NAD(P) + (or NAD(P)H2, respectively) and, to a lower extent, ATP, pyruvate and oxalacetate. In any case, acetyl-CoA can be considered as the central metabolite both for biomass formation and PHB biosynthesis. This compound stems from the catabolic break down of carbon substrates like sugars (mainly catabolized by the 2-Keto-3-desoxy-6-phosphogluconate pathway) or fatty acids (converted by 6-oxidation). 

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