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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]
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.
ChREBP is translocated to the nucleus and binds to DNA after dephosphorylation of a p-Ser and a p-Thr residue by PP2A, which itself is activated by xylulose-5-phosphate. Xu5p is produced in the pentose phosphate pathway when levels of Glucose-6-phosphate are high (the cell has ample glucose). In the liver, ChREBP mediates activation of several ...
In this phase, two molecules of NADP + are reduced to NADPH, utilizing the energy from the conversion of glucose-6-phosphate into ribulose 5-phosphate. Oxidative phase of pentose phosphate pathway. Glucose-6-phosphate ( 1 ), 6-phosphoglucono-δ-lactone ( 2 ), 6-phosphogluconate ( 3 ), ribulose 5-phosphate ( 4 )
In this pathway the enzyme xylose isomerase converts D-xylose directly into D-xylulose. D-xylulose is then phosphorylated to D-xylulose-5-phosphate as in the oxido-reductase pathway. At equilibrium, the isomerase reaction results in a mixture of 83% D-xylose and 17% D-xylulose because the conversion of xylose to xylulose is energetically ...
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 ...
In Arabidopsis thaliana 1-deoxy-D-xylulose 5-phosphate reductoisomerase is the first committed enzyme of the MEP pathway for isoprenoid precursor biosynthesis. The enzyme requires Mn 2+, Co 2+ or Mg 2+ for activity, with Mn 2+ being most effective.