IUBMB Enzyme Nomenclature


Accepted name: D-tagatose 3-epimerase

Reaction: (1) D-tagatose = D-sorbose
(2) D-psicose = D-fructose

For diagram of reaction click here.

Glossary: D-psicose = D-ribo-hex-2-ulose

Other name(s): L-ribulose 3-epimerase; ketose 3-epimerase

Systematic name: D-tagatose 3-epimerase

Comments: The enzymes isolated from the bacteria Pseudomonas cichorii [2], Pseudomonas sp. ST-24 [1], Rhodobacter sphaeroides [3] and Mesorhizobium loti [4] catalyse the epimerization of various ketoses at the C3 position, interconverting D-fructose and D-psicose, D-tagatose and D-sorbose, D-ribulose and D-xylulose, and L-ribulose and L-xylulose. The specificity depends on the species. The enzymes from Pseudomonas cichorii and Rhodobacter sphaeroides require Mn2+ [2,3].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Itoh, H., Okaya, H., Khan, A. R., Tajima, S., Hayakawa, S., Izumori, K. Purification and characterization of D-tagatose 3-epimerase from Pseudomonas sp. ST-24. Biosci. Biotechnol. Biochem. 58 (1994) 2168-2171.

2. Yoshida, H., Yamada, M., Nishitani, T., Takada, G., Izumori, K. and Kamitori, S. Crystal structures of D-tagatose 3-epimerase from Pseudomonas cichorii and its complexes with D-tagatose and D-fructose. J. Mol. Biol. 374 (2007) 443-453. [PMID: 17936787]

3. Zhang, L., Mu, W., Jiang, B. and Zhang, T. Characterization of D-tagatose-3-epimerase from Rhodobacter sphaeroides that converts D-fructose into D-psicose. Biotechnol. Lett. 31 (2009) 857-862. [PMID: 19205890]

4. Uechi, K., Takata, G., Fukai, Y., Yoshihara, A. and Morimoto, K. Gene cloning and characterization of L-ribulose 3-epimerase from Mesorhizobium loti and its application to rare sugar production. Biosci. Biotechnol. Biochem. 77 (2013) 511-515. [PMID: 23470755]

[EC created 2014]

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