IUBMB Enzyme Nomenclature


Accepted name: L-arabinose isomerase

Reaction: L-arabinose = L-ribulose

For diagram of reaction click here.

Other Name(s): L-arabinose ketol-isomerase

Systematic name: L-arabinose aldose-ketose-isomerase

Comments: Requires a divalent metal ion (the enzyme from the bacterium Escherichia coli prefers Mn2+) [2]. The enzyme binds the closed form of the sugar and catalyses ring opening to generate a form of open-chain conformation that facilitates the isomerization reaction, which proceeds via an ene-diol mechanism [5]. The enzyme can also convert D-galactose to D-tagatose with lower efficiency [4].

Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9023-80-7


1. Heath, E.C., Horecker, B.L., Smyrniotis, P.Z. and Takagi, Y. Pentose formation by Lactobacillus plantarum. II. L-Arabinose isomerase. J. Biol. Chem. 231 (1958) 1031-1037.

2. Patrick, J.W. and Lee, N. Purification and properties of an L-arabinose isomerase from Escherichia coli. J. Biol. Chem. 243 (1968) 4312-4318. [PMID: 4878429]

3. Nakamatu, T. and Yamanaka, K. Crystallization and properties of L-arabinose isomerase from Lactobacillus gayonii. Biochim. Biophys. Acta 178 (1969) 156-165. [PMID: 5773448]

4. Cheetham, P.S.J. and Wootton, A.N. Bioconversion of D-galactose into D-tagatose. Enzyme Microb. Technol. 15 (1993) 105-108.

5. Banerjee, S., Anderson, F. and Farber, G.K. The evolution of sugar isomerases. Protein Eng. 8 (1995) 1189-1195. [PMID: 8869631]

6. Manjasetty, B.A. and Chance, M.R. Crystal structure of Escherichia coli L-arabinose isomerase (ECAI), the putative target of biological tagatose production. J. Mol. Biol. 360 (2006) 297-309. [PMID: 16756997]

[EC created 1961]

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