An alternative glycolytic pathway carried out chiefly by certain bacteria whereby glucose is metabolized and converted to pyruvate, and results in a gain of ATP, NADH, and NADPH molecules
Cellular respiration is a cellular process comprised of glycolysis, Krebs cycle, and oxidative phosphorylation. Glycolysis is the stage in cellular respiration involved in the degradation of a simple sugar to pyruvate in order to yield high-energy molecules (e.g. ATP and NADH). The Embden-Meyerhof-Parnas (EMP) pathway is the most common and well-known type of glycolytic pathway. Thus, it is sometimes used synonymously with glycolysis. In this pathway, the net energy yield is expected to be two NADH and two ATP molecules.
The Entner-Duodoroff pathway is an alternative glycolytic pathway that is observed in certain bacteria. It was once thought to be exclusive to be prokaryotic however it was also observed in certain plant species, such as Hordeum vulgare.1 Examples of bacteria that uses this pathway are Pseudomonas, Azotobacter, Rhizobium, Escherichia coli, Enterococcus faecalis, and Xanthomonas campestris.
Similar to the EMP pathway, the Entner-Doudoroff pathway is comprised of two fundamental phases. It differs though from the EMP pathway in many ways such that in the first phase glucose is metabolized and converted to 2-keto-3-deoxygluconate-6-phosphate (KDPG). In EMP pathway, fructose 1, 6-bisphosphate is the metabolite that is split into two triose phosphates, glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate. In the Entner-Doudoroff pathway, the KDPG is split into one G3P and one pyruvate. In the second phase, the G3P is metabolized and eventually converted to another pyruvate.
In the initial phase of the Entner-Duodoroff pathway, one ATP molecule is used and one NADPH is produced. In the second phase, one NADH and two ATP molecules are produced. Since energy from ATP is utilized in the first phase, the energy net gain from the Entner-Duodoroff pathway would be one NADPH, one NADH, and one ATP.
The name of this glycolytic pathway is derived from the names of Nathan Entner and Michael Doudoroff who first reported the pathway in 1952.
- ED pathway
1 Chen, Xi, et al. “The Entner–Doudoroff pathway is an overlooked glycolytic route in cyanobacteria and plants.” Proceedings of the National Academy of Sciences (2016): 201521916.