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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]
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 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.
This pathway, called methyl-D-erythritol phosphate (MEP) or non-mevalonate pathway, is responsible for biosynthesis of isoprenoids—molecules required for cell survival in most pathogenic bacteria and hence will be helpful in most usually antibacterial resistant bacteria.
Thus, the two substrates of this enzyme are D-xylulose 5-phosphate and formaldehyde, whereas its two products are glyceraldehyde 3-phosphate and glycerone. This enzyme belongs to the family of transferases , specifically those transferring aldehyde or ketonic groups (transaldolases and transketolases, respectively).
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.