The enzyme pseudouridylate synthase () catalyzes the chemical reaction
This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is uracil hydro-lyase (adding <small>D</small>-ribose 5-phosphate pseudouridine-5â²-phosphate-forming). Other names in common use include pseudouridylic acid synthetase, pseudouridine monophosphate synthetase, 5-ribosyluracil 5-phosphate synthetase, pseudouridylate synthetase, upsilonUMP synthetase, and uracil hydro-lyase (adding <small>D</small>-ribose 5-phosphate). This enzyme participates in pyrimidine metabolism.
As of late 2007, 22 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , , , , , , , and .