Xylulose-5-phosphate

Structural formula
	Deprotonated form of D- xylulose-5-phosphate
General
Surname	Xylulose-5-phosphate
other names	Xylulose-5-P; Xu-5-P; X5P; (2,3,5-trihydroxy-4-oxopentyl) dihydrogen phosphate ( IUPAC ) ;
Molecular formula	C 5 H 11 O 8 P; C 5 H 9 O 8 P 2− (deprotonated, physiological form); C 5 H 10 NaO 8 P ( sodium salt );
External identifiers / databases
PubChem	850
Wikidata	Q37864045
properties
Molar mass	230.11 g mol −1
Physical state	firmly
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Xylulose-5-phosphate is the form of pentose phosphorylated on the C5 atom. Xylulose is a metabolic intermediate in many living things. Only the D isomer occurs in nature .

meaning

Xylulose-5-phosphate (XP5) is an important intermediate in the pentose phosphate pathway and can be epimerized there from ribulose-5-phosphate . This reaction catalyzes a ribulose phosphate-3-epimerase . Xylulose-5-phosphate and ribose-5-phosphate are then converted in the pentose phosphate pathway by a transketolase into sedoheptulose-7-phosphate and glyceraldehyde-3-phosphate .

Xylulose-5-phosphate also has a function as a signaling molecule . It arises in the pentose phosphate pathway, which occurs more intensely in the liver when the blood sugar level is high - as does glycolysis . There, XP5 stimulates protein phosphatase 2A (PP2A), which dephosphorylates the bifunctional enzyme PFKFB . In this form, the kinase function is activated, whereby fructose-2,6-bisphosphate is increasingly formed. In turn, fructose-2,6-bisphosphate activates phosphofructokinase (PFK), the control point of glycolysis. As a result, glycolysis takes place more intensely, and a lot of pyruvate or acetyl-CoA is formed .

At the same time, PP2A also dephosphorylates a transcription factor , the carbohydrate-responsive element-binding protein ChREBP, which is activated as a result. ChREBP stimulates the reading of the genes for lipid synthesis and fatty acid synthesis can begin.

In the combination, acetyl-CoA is produced from glycolysis and NADPH from the pentose phosphate pathway, which are required for the formation of fatty acids. This means that excess glucose is used to build up fats as a result of good nutrition.

Individual evidence

↑ ^a ^b Data sheet D-Xylulose 5-phosphate sodium salt, ≥80% (TLC) from Sigma-Aldrich , accessed on May 9, 2017 ( PDF ).
^ Reginald Garrett and Charles M. Grisham: Biochemistry . (International Student Edition). 4th edition 2009, Cengage Learning Services, ISBN 978-0-495-11464-2 , pp. 692-693.
↑ Iizuka, K. and Horikawa, Y. (2008): A glucose-activated transcription factor involved in the development of metabolic syndrome . In: Endocr. J . 55 (4); Pp. 617-624; PMID 18490833 ; PDF (free full text access).

[Sigma-1] Data sheet D-Xylulose 5-phosphate sodium salt, ≥80% (TLC) from Sigma-Aldrich , accessed on May 9, 2017 ( PDF ).

[2] Reginald Garrett and Charles M. Grisham: Biochemistry . (International Student Edition). 4th edition 2009, Cengage Learning Services, ISBN 978-0-495-11464-2 , pp. 692-693.

[3] Iizuka, K. and Horikawa, Y. (2008): A glucose-activated transcription factor involved in the development of metabolic syndrome . In: Endocr. J . 55 (4); Pp. 617-624; PMID 18490833 ; PDF (free full text access).