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hexose monophosphate shunt, pentose phosphate pathway or phosphogluconate shunt
Biochemistry:
- source of ribose
- thought to provide reducing equivalents for Cyt P450
- NADPH is generated when glucose is oxidized to ribose-5-phosphate
- the Hexose Monophosphate Shunt also catalyzes the inter-conversion of 3, 4, 5, 6, & 7-carbon sugars in a series of non oxidative reactions
- all of these reactions occur in the cytoplasm
* see figure
- hexose monophosphate shunt 1
- enzyme: glucose-6-phosphate dehydrogenase
- substrate: glucose-6-phosphate + NADP
- product: 6-phosphogluconolactone + NADPH
- hexose monophosphate shunt 2
- enzyme: lactonase
- substrate: 6-phosphogluconolactone + H2O
- product: 6-phosphogluconate
- hexose monophosphate shunt 3
- enzyme: 6-phosphogluconate dehydrogenase
- substrate: 6-phosphogluconate + NADP
- product: ribulose-5-phosphate + NADPH
- hexose monophosphate shunt 4
- enzyme: phosphopentose isomerase
- substrate: ribulose-5-phosphate
- product: ribose-5-phosphate)
- hexose monophosphate shunt 5
- enzyme: phosphopentose epimerase
- substrate: ribulose-5-phosphate
- product: xylulose-5-phosphate
- hexose monophosphate shunt 6
- enzyme: transketolase
- substrate: xylulose-5-phosphate + ribose-5-phosphate
- product: sedoheptulose-7-phosphate + glyceraldehyde-3-phosphate
- hexose monophosphate shunt 7
- enzyme: transaldolase
- substrate: sedoheptulose-7-phosphate + glyceraldehyde-3-phosphate
- product: fructose-6-phosphate + erythrose-4-phosphate
- hexose monophosphate shunt 8
- enzyme: transketolase
- substrate: xylulose-5-phosphate + erythrose-4-phosphate
- product: fructose-6-phosphate + glyceraldehyde-3-phosphate
General
biosynthetic pathway or anabolic pathway
Database Correlations
Kegg map/map00030
References
http://www.genome.ad.jp/kegg/pathway/map/map00030.html