Pathway · 2 proteins
Fructose and mannose metabolism
Proteins of this group that KEGG places on its “Fructose and mannose metabolism” map for Aquifex aeolicus.
How it works
This map covers six-carbon sugars other than glucose. The two proteins here are a sugar-phosphate aldolase of unknown target, and the bifunctional fructose-1,6-bisphosphate aldolase/phosphatase, which carries out two steps of sugar building with one enzyme.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Fuculose-1-phosphate aldolase | — | — | — | 187 | Unspecified |
| Fructose-1,6-bisphosphate aldolase/phosphatase | 3.1.3.11; 4.1.2.13 | beta-D-fructose 1,6-bisphosphate + H2O = beta-D-fructose 6-phosphate + phosphate | Mg(2+), beta-D-fructose 1,6-bisphosphate | 381 | Unspecified |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Ribose 5-phosphate isomerase BHome: Ribose and PRPP supply | — | — | D-ribulose 5-phosphate | 154 | Step named |
| Fructose-1,6-bisphosphate aldolase class IIHome: Glycolysis / Gluconeogenesis | — | — | Zn(2+) | 310 | Step named |
| ATP-dependent 6-phosphofructokinaseHome: Glycolysis / Gluconeogenesis | 2.7.1.11 | beta-D-fructose 6-phosphate + ATP = beta-D-fructose 1,6-bisphosphate + ADP + H(+) | Mg(2+) | 321 | Step named |
| Triosephosphate isomeraseHome: Glycolysis / Gluconeogenesis | 5.3.1.1 | D-glyceraldehyde 3-phosphate = dihydroxyacetone phosphate | — | 247 | Step named |
| mannose-1-phosphate guanylyltransferaseHome: Amino sugar and nucleotide sugar metabolism | 2.7.7.13 | alpha-D-mannose 1-phosphate + GTP + H(+) = GDP-alpha-D-mannose + diphosphate | — | 453 | Step named |
| Mannose-1-phosphate guanyltransferaseHome: Amino sugar and nucleotide sugar metabolism | — | — | — | 831 | Step named |
| Bifunctional phosphoglucose/phosphomannose isomeraseHome: Glycolysis / Gluconeogenesis | 5.3.1.8; 5.3.1.9 | alpha-D-glucose 6-phosphate = beta-D-fructose 6-phosphate | D-fructose 6-phosphate | 320 | Step named |
| 2-amino-3,7-dideoxy-D-threo-hept-6-ulosonate synthaseHome: Phenylalanine, tyrosine and tryptophan biosynthesis | 2.2.1.10 | 1-deoxy-D-threo-hexo-2,5-diulose 6-phosphate + L-aspartate 4-semialdehyde = 2,3-dioxopropyl phosphate + 2-amino-2,3,7-trideoxy-D-lyxo-hept-6-ulosonate | 1-deoxy-D-threo-hexo-2,5-diulose 6-phosphate | 264 | Step named |
| GDP-mannose 4,6-dehydrataseHome: Biosynthesis of various nucleotide sugars | 4.2.1.47 | GDP-alpha-D-mannose = GDP-4-dehydro-alpha-D-rhamnose + H2O | — | 345 | Unspecified |
Origins
Could sugars like fructose have been made and converted before enzymes?
How it was discovered
- 1943Two different forms of fructose-1,6-bisphosphate aldolase are found, in yeast and in rabbit muscle: the same reaction carried out by two unrelated enzymes.Rana, The Cell's Design
Poor yields once led to pessimism about the prebiotic synthesis of ribose. Eschenmoser and colleagues then obtained high yields of ribose 2,4-bisphosphate under controlled conditions from glycolaldehyde phosphate and formaldehyde.
Those yields depend on controlled conditions and a phosphorylated starting material.
Aquifex uses one enzyme for two steps of sugar building: it joins two three-carbon units and removes a phosphate. Rana argues that the same function carried out by unrelated molecules fits design better than chance.
From the books: Zubay, Origins of Life on Earth and in the Cosmos, p. 219; Rana, The Cell's Design.
The wider question for this part of the cell: origins for conserved, but we cannot say what they do.
Sources
- KEGG map aae00051 (enzymes of this organism highlighted)
Other pathways in this group: tRNA charging · Nutrient and metabolic state · Biosynthesis of various nucleotide sugars · Purine metabolism · Bacterial secretion system · Glyoxylate and dicarboxylate metabolism · Starch and sucrose metabolism · Homologous recombination · Streptomycin biosynthesis · Other carbon fixation pathways · Nicotinate and nicotinamide metabolism · Not yet placed in a pathway