In enzymology, a pyrimidine-5'-nucleotide nucleosidase () is an enzyme that catalyzes the chemical reaction a pyrimidine 5'-nucleotide + H2O D-ribose 5-phosphate + a pyrimidine base Thus, the two substrates of this enzyme are pyrimidine 5'-nucleotide and H2O, whereas its two products are D-ribose 5-phosphate and pyrimidine base. This enzyme belongs to the family of hydrolases, specifically those glycosylases that hydrolyse N-glycosyl compounds. The systematic name of this enzyme class is pyrimidine-5'-nucleotide phosphoribo(deoxyribo)hydrolase. Other names in common use include pyrimidine nucleotide N-ribosidase, and Pyr5N. This enzyme participates in pyrimidine metabolism. References EC 3.2.2 Enzymes of unknown structure