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Figure 7 | Kinetoplastid Biology and Disease

Figure 7

From: Evolution of energy metabolism and its compartmentation in Kinetoplastida

Figure 7

Pentose-phosphate pathway. A. Scheme of a possible pentosephosphate pathway variant in Trypanosomatidae. B. Scheme of a classical pentosephosphate pathway. It is proposed that the aldolase of Trypanosomatidae shares a bifunctional activity with its homologues from chloroplasts; in addition to its glycolytic/gluconeogenic activity, it may condense dihydroxyacetone phosphate and erythrose 4-phosphate to sedoheptulose 1,7-bisphosphate. Sedoheptulose-1,7-bisphosphatase will then dephosphorylate this product, producing fructose 6-phosphate (for another round through the pentosephosphate pathway after its isomerisation to glucose 6-phosphate by glucose-6-phosphate isomerase – to produce NAPDH, or for glycolysis – to produce ATP) and erythrose 4-phosphate (for further metabolism, e.g. to be converted, together with xylulose 5-phosphate into fructose 6-phosphate and glyceraldehyde 3-phosphate (for further breakdown by glycolysis) by transketolase. Enzymes: 1. hexokinase; 2, glucose-6-phosphate dehydrogenase, 3, 6-phosphogluconate lactonase; 4, 6-phosphogluconate dehydrogenase; 5, ribulose-5-phosphate 3-epimerase; 6, ribose-5-phosphate isomerase; 7, transaldolase; 8, transketolase; 9, glucose-6-phosphate isomerase; 10, phosphofructokinase, 11, triosephosphate isomerase.

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