Ribulose-phosphate 3-epimerase

In enzymology, a ribulose-phosphate 3-epimerase is an enzyme that catalyzes the chemical reaction


 * D-ribulose 5-phosphate $$\rightleftharpoons$$ D-xylulose 5-phosphate

Hence, this enzyme has one substrate, D-ribulose 5-phosphate, and one product, D-xylulose 5-phosphate.

This enzyme belongs to the family of isomerases, specifically those racemases and epimerases acting on carbohydrates and derivatives. The systematic name of this enzyme class is D-ribulose-5-phosphate 3-epimerase. Other names in common use include phosphoribulose epimerase, erythrose-4-phosphate isomerase, phosphoketopentose 3-epimerase, xylulose phosphate 3-epimerase, phosphoketopentose epimerase, ribulose 5-phosphate 3-epimerase, D-ribulose phosphate-3-epimerase, D-ribulose 5-phosphate epimerase, D-ribulose-5-P 3-epimerase, D-xylulose-5-phosphate 3-epimerase, and pentose-5-phosphate 3-epimerase. This enzyme participates in 3 metabolic pathways: pentose phosphate pathway, pentose and glucuronate interconversions, and carbon fixation.

Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes, , , and.