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D-Xylulose 5-phosphate (D-xylulose-5-P) is an intermediate in the pentose phosphate pathway. It is a ketose sugar formed from ribulose-5-phosphate by ribulose-5-phosphate epimerase. In the non-oxidative branch of the pentose phosphate pathway, xylulose-5-phosphate acts as a donor of two-carbon ketone groups in transketolase reactions. [2]
The systematic name of this enzyme class is pyruvate: d-glyceraldehyde-3-phosphate acetaldehydetransferase (decarboxylating). Other names in common use include 1-deoxy-d-xylulose-5-phosphate pyruvate-lyase (carboxylating), and DXP-synthase. This enzyme participates in biosynthesis of steroids.
The enzyme involved in making 1-deoxy-d-xylulose 5-phosphate (DXP) is DXP synthase. [2] The mechanism follows a catalysis of decarboxylative condensation of pyruvate and d-glyceraldehyde 3-phosphate to produce DXP. [2] [3] In addition, the molecule is involved in making thiamine (vitamin B 1) and pyridoxol (vitamin B 6). [2]
The second reaction catalyzed by transketolase in the pentose phosphate pathway involves the same thiamine diphosphate-mediated transfer of a 2-carbon fragment from D-xylulose-5-P to the aldose erythrose-4-phosphate, affording fructose 6-phosphate and glyceraldehyde-3-P. Again, the same reaction occurs in the Calvin cycle but in the opposite ...
XR is reducing D-xylose to xylitol using NADH or NADPH. Xylitol is then oxidized to D-xylulose by XDH, using the cofactor NAD. In the last step D-xylulose is phosphorylated by an ATP utilising kinase, XK, to result in D-xylulose-5-phosphate which is an intermediate of the pentose phosphate pathway.
The systematic name of this enzyme class is D-xylulose-5-phosphate:formaldehyde glycolaldehydetransferase. This enzyme is also called dihydroxyacetone synthase. This enzyme participates in methane metabolism. It employs one cofactor, thiamin diphosphate.
In enzymology, a xylulokinase (EC 2.7.1.17) is an enzyme that catalyzes the chemical reaction. ATP + D-xylulose ⇌ ADP + D-xylulose 5-phosphate. Thus, the two substrates of this enzyme are ATP and D-xylulose, whereas its two products are ADP and D-xylulose 5-phosphate.
The mevalonate pathway (MVA pathway or HMG-CoA reductase pathway) and the MEP pathway are metabolic pathways for the biosynthesis of isoprenoid precursors: IPP and DMAPP. . Whereas plants use both MVA and MEP pathway, most organisms only use one of the pathways for the biosynthesis of isoprenoid precurs