In enzymology, a 1-deoxy--xylulose-5-phosphate synthase () is an enzyme in the non-mevalonate pathway that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are pyruvate and -glyceraldehyde 3-phosphate, whereas its two products are 1-deoxy--xylulose 5-phosphate and CO<sub>2</sub>.
This enzyme belongs to the family of transferases, specifically those transferring aldehyde or ketonic groups (transaldolases and transketolases, respectively). The systematic name of this enzyme class is pyruvate:-glyceraldehyde-3-phosphate acetaldehydetransferase (decarboxylating). Other names in common use include 1-deoxy--xylulose-5-phosphate pyruvate-lyase (carboxylating), and DXP-synthase. This enzyme participates in biosynthesis of steroids.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .