Archaea have variants of the Entner-Doudoroff Pathway. These variants are called the semiphosphorylative ED (spED) and the nonphosphorylative ED (npED):
* spED is found in halophilic euryachaea and Clostridium species.
* In spED, the difference is where phosphorylation occurs. In the standard ED, phosphorylation occurs at the first step from glucose to G-6-P. In spED, the glucose is first oxidized to gluconate via a glucose dehydrogenase. Next, gluconate dehydratase converts gluconate into 2-keto-3-deoxy-gluconate (KDG). The next step is where phosphorylation occurs as KDG kinase converts KDG into KDPG. KDPG is then cleaved into glyceraldehyde 3-phosphate (GAP) and pyruvate via KDPG aldolase and follows the same EMP pathway as the standard ED. This pathway produces the same amount of ATP as the standard ED.
* npED is found in thermoacidophilic Sulfolobus, Euryarchaeota Tp. acidophilum, and Picrophilus species.
* In npED, there is no phosphorylation at all. The pathway is the same as spED but instead of phosphorylation occurring at KDG, KDG is instead cleaved GA and pyruvate via KDG aldolase. From here, GA is oxidized via GA dehydrogenase into glycerate. The glycerate is phosphorylated by glycerate kinase into 2PG. 2PG then follows the same pathway as ED and is converted into pyruvate via ENO and PK. In this pathway though, there is no ATP produced.
Some archaea such as Crenacraeota Sul. solfacaricus and Tpt. tenax have what is called branched ED. In branched ED, the organism have both spED and npED that are both operative and work in parallel.