text: Sulfoglycolysis is a catabolic process in primary metabolism in which sulfoquinovose (6-deoxy-6-sulfonato-glucose) is metabolized to produce energy and carbon-building blocks. Sulfoglycolysis pathways occur in a wide variety of organisms, and enable key steps in the degradation of  sulfoquinovosyl diacylglycerol (SQDG), a sulfolipid found in plants and cyanobacteria into sulfite and sulfate. Sulfoglycolysis converts sulfoquinovose (CHOS) into various smaller metabolizable carbon fragments such as pyruvate and dihydroxyacetone phosphate that enter central metabolism. The free energy is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide). Unlike glycolysis, which allows metabolism of all carbons in glucose, sulfoglycolysis pathways convert only a fraction of the carbon content of sulfoquinovose into smaller metabolizable fragments; the remainder is excreted as C-sulfonates 2,3-dihydroxypropanesulfonate (DHPS) or sulfolactate (SL); or C-sulfonates isethionate or sulfoacetate.
  Several sulfoglycolytic pathways are known:
  * The sulfoglycolytic Embden-Meyerhof-Parnas (sulfo-EMP) pathway, first identified in Escherichia coli, involves the degradation of sulfoquinovose to 2,3-dihydroxypropanesulfonate (DHPS), and shares similarity with the Embden-Meyerhof-Parnas glycolysis pathway. This pathway leads to the production of the C3 intermediate dihydroxyacetone phosphate. 
  * The sulfoglycolytic Entner-Doudoroff (sulfo-ED) pathway, first identified in Pseudomonas putida SQ1, involves the degradation of sulfoquinovose to sulfolactate, and shares similarity to the Entner-Doudoroff pathway of glycolysis. This pathway leads to the production of the C3 intermediate pyruvate. 
  * The sulfofructose transaldolase pathway, first identified in Bacillus aryabhattai  and Bacillus megaterium, involves isomerization of SQ to sulfofructose, and then a transaldolase cleaves SF to 3-sulfolactaldehyde (SLA), while the non-sulfonated C3-(glycerone)-moiety is transferred to an acceptor molecule, glyceraldehyde phosphate (GAP), yielding fructose-6-phosphate (F6P). The SLA released can either be oxidized (to sulfolactate) or reduced (to dihydroxypropanesulfonate) and then excreted.
  * The sulfoglycolytic transketolase (sulfo-TL) pathway was first identified in Clostridium sp. MSTE9. It involves isomerization of SQ to sulfofructose, and then a transketolase cleaves SF to 4-sulfoerythrose (SE), while the C2-moiety is transferred to an acceptor molecule, glyceraldehyde phosphate (GAP), yielding xylulose-5-phosphate (Xu5P). 4-Sulfoerythrose is isomerized to 4-sulfoerythrulose (SEu), whereupon a second round of transketolase catalyzed reaction cleaves SE to sulfoacetaldehyde, while the non-sulfonated C2-moiety is transferred to an acceptor molecule, glyceraldehyde phosphate (GAP), yielding a second molecule of xylulose-5-phosphate (Xu5P). Finally, the sulfoacetaldehyde is reduced to isethionate and excreted. 
  Additionally, there are sulfoquinovose sulfolytic pathways that allow degradation of sulfoquinovose through cleavage of the C-S bond. These include:
  * The sulfoglycolytic sulfoquinovose monooxygenase (sulfo-SMO) pathway, first identified in Agrobacterium tumerfaciens  and Novosphingobium aromaticivorans, involves the degradation of sulfoquinovose to glucose and sulfite. Glucose formed in this pathway enters glycolysis. 
  * The sulfoglycolytic sulfoquinovose dioxygenase (sulfo-SMO) pathway.
  In all pathways, energy is formed by breakdown of the carbon-rich fragments in later stages through the pay-off phase of glycolysis through substrate-level phosphorylation to produce ATP and NADH.