In enzymology, an arabinose isomerase () is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, D-arabinose, 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-arabinose aldose-ketose-isomerase. Other names in common use include D-arabinose(L-fucose) isomerase, D-arabinose isomerase, L-fucose isomerase, and D-arabinose ketol-isomerase.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code .