Entner-Doudoroff pathway through 6-phosphogluconate

Definition

Target type: biologicalprocess

A pathway that converts a carbohydrate to pyruvate and glyceraldehyde-3 phosphate by producing 6-phosphogluconate and then dehydrating it. [GOC:jl, MetaCyc:PWY-8004, PMID:12921356, PMID:12981024]

The Entner-Doudoroff (ED) pathway is an alternative route for glucose catabolism that diverges from the conventional glycolytic pathway at the level of 6-phosphogluconate. It is prevalent in bacteria and some other organisms, including certain photosynthetic bacteria, as well as in some archaea. This pathway generates energy (ATP) and reducing power (NADPH) from glucose, although it produces fewer ATP molecules than glycolysis.

The ED pathway begins with glucose being phosphorylated to glucose-6-phosphate by hexokinase. This step is identical to the first step of glycolysis.

Then, glucose-6-phosphate is oxidized to 6-phosphogluconate by glucose-6-phosphate dehydrogenase, generating NADPH. This NADPH is essential for biosynthesis and detoxification reactions within the cell.

The 6-phosphogluconate is then dehydrated by 6-phosphogluconate dehydratase to produce 2-keto-3-deoxy-6-phosphogluconate (KDPG). This is a crucial step in the ED pathway, as it leads to the formation of a unique intermediate that distinguishes this pathway from glycolysis.

The KDPG is then cleaved by KDPG aldolase, producing pyruvate and glyceraldehyde-3-phosphate (G3P). This step is analogous to the conversion of fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate in glycolysis.

The pyruvate produced in this step can then be further metabolized to generate ATP through the tricarboxylic acid (TCA) cycle.

Meanwhile, G3P is a key intermediate in glycolysis and can enter that pathway to continue the production of ATP.

In summary, the ED pathway provides a viable alternative to glycolysis for energy production in certain organisms. Its distinct enzymatic steps and intermediates contribute to its unique metabolic role. The pathway's ability to generate both ATP and NADPH makes it crucial for the biosynthesis, detoxification, and overall metabolic balance of the organisms that employ it.'
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Proteins (1)

Compounds (1)