Путь Энтера-Дудорова: биохимические реакции и метаболизм.

Series of interconnected biochemical reactions
The Entner–Doudoroff pathway (ED Pathway) is a metabolic pathway that is most notable in Gram negative bacteria, certain Gram positive bacteria and archaea. While originally thought to be just an alternative to glycolysis (EMP) and the pentose phosphate pathway (PPP), some studies now suggest that the original role of the EMP may have originally been about anabolism and repurposed over time to catabolism, meaning the ED pathway may be the older pathway. Recent studies have also shown the prevalence of the ED pathway may be more widespread than first predicted with evidence supporting the presence of the pathway in cyanobacteria, ferns, algae, mosses, and plants. Specifically, there is direct evidence that Hordeum vulgare uses the Entner–Doudoroff pathway.

The G6P is then converted to 6 phosphogluconolactone in the presence of enzyme glucose 6 phosphate dehydrogenase (an oxido reductase) with the presence of co enzyme nicotinamide adenine dinucleotide phosphate (NADP+). which will be reduced to nicotinamide adenine dinucleotide phosphate hydrogen along with a free hydrogen atom H+.

The 6PGL is converted into 6 phosphogluconic acid in the presence of enzyme hydrolase.

The 6 phosphogluconic acid is converted to 2 keto 3 deoxy 6 phosphogluconate (KDPG) in the presence of enzyme 6 phosphogluconate dehydratase; in the process, a water molecule is released to the surroundings.

The KDPG is then converted into pyruvate and glyceraldehyde 3 phosphate in the presence of enzyme KDPG aldolase. For the pyruvate, the ED pathway ends here, and the pyruvate then goes into further metabolic pathways (TCA cycle, ETC cycle, etc). The other product (glyceraldehyde 3 phosphate) is further converted by entering into the glycolysis pathway, via which it, too, gets converted into pyruvate for further metabolism.

The G3P is converted to 1,3 bisphosphoglycerate in the presence of enzyme glyceraldehyde 3 phosphate dehydrogenase (an oxido reductase). The aldehyde groups of the triose sugars are oxidised, and inorganic phosphate is added to them, forming 1,3 bisphosphoglycerate. The hydrogen is used to reduce two molecules of NAD+, a hydrogen carrier, to give NADH + H+ for each triose. Hydrogen atom balance and charge balance are both maintained because the phosphate (Pi) group actually exists in the form of a hydrogen phosphate anion (HPO42−), which dissociates to contribute the extra H+ ion and gives a net charge of 3 on both sides.

This step is the enzymatic transfer of a phosphate group from 1,3 bisphosphoglycerate to ADP by phosphoglycerate kinase, forming ATP and 3 phosphoglycerate.

Phosphoglycerate mutase isomerises 3 phosphoglycerate into 2 phosphoglycerate.