In enzymology, a ribose isomerase () is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, D-ribose, and one product, D-ribulose.
This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. The systematic name of this enzyme class is D-ribose aldose-ketose-isomerase. Other names in common use include D-ribose isomerase, and D-ribose ketol-isomerase.