2-Keto-3-deoxy-6-phosphogluconate (KDPG) is a key intermediate exclusively in the Entner-Doudoroff Pathway.
This compound plays a central role in bacterial sugar metabolism, distinguishing it from other major pathways.

2-Keto-3-deoxy-6-phosphogluconate, often abbreviated as KDPG, is a critical metabolic intermediate in bacterial carbohydrate breakdown. As a life sciences student focusing on biochemistry and molecular biology, understanding KDPG’s role helps in exam preparation for pathways like Entner-Doudoroff. It forms via dehydration of 6-phosphogluconate and splits into pyruvate and glyceraldehyde-3-phosphate by KDPG aldolase.

Pathway Options Explained

Pentose Phosphate Pathway

This oxidative and non-oxidative shunt generates NADPH and ribose-5-phosphate from glucose-6-phosphate. Key intermediates include 6-phosphogluconolactone and ribulose-5-phosphate, but not KDPG, which requires dehydration absent here.​

Entner-Doudoroff Pathway

KDPG defines this alternative glycolysis in many Gram-negative bacteria and archaea. Glucose-6-phosphate oxidizes to 6-phosphogluconate, then dehydrates to KDPG—the pathway’s hallmark—yielding one ATP and one NADH per glucose, less efficient than classical glycolysis.

Embden-Meyerhof Pathway

Also called glycolysis, this converts glucose to pyruvate via fructose-1,6-bisphosphate and phosphoenolpyruvate. No oxidation to gluconate derivatives occurs, so KDPG is absent; it’s universal in most organisms.​

Tricarboxylic Acid Cycle

The TCA (Krebs) cycle oxidizes acetyl-CoA to CO₂, producing NADH/FADH₂ and GTP. Intermediates like citrate, α-ketoglutarate, and oxaloacetate dominate; KDPG plays no role as it’s a sugar catabolic precursor.​

Correct Answer

Entner-Doudoroff Pathway. KDPG’s accumulation even signals carbon catabolite repression in some bacteria, underscoring its specificity.