Arabinose Isomerases

Arabinose isomerase [EC 5.3.1.3] catalyzes the interconversion of D-arabinose and D-ribulose. The enzyme will also utilize L-fucose and more slowly utilize L-galactose and D-altrose as substrates. L-Arabinose isomerase [EC 5.3.1.4] catalyzes the interconversion of L-arabinose and L-ribulose. 

HYDRATION WATER a-L-ARABINOFURANOSIDASE d-ARABINOKINASE ARABINONATE DEHYDRATASE ARABINOSE ISOMERASE ARABINOSE-5-PHOSPHATE ISOMERASE Arachidonate 5-lipoxygenase, 5-LIPOXYGENASE ARACHIDONYL-CoA SYNTHETASE Arene oxide intermediate,... 

These enzymes vary widely in secondary and tertiary structure.1273 Mannose-6-phosphate isomerase is a 45 kDa Zn2+-containing monomer. The larger 65 kDa L-fucose isomerase, which also acts on D-arabinose, is a hexameric Mn2+-dependent enzyme.1273 L-Arabinose isomerase of E. coli, which interconverts arabinose and L-ribulose, is a hexamer of 60-kDa subunits128 while the D-xylose isomerase of Streptomyces is a tetramer of 43-kDa subunits.129 The nonenzymatic counterpart of the isomerization catalyzed by the enzyme is the base-catalyzed Lobry deBruyn-Alberda van Ekenstein transformation (Eq. 13-25).130... 

L-arabinose isomerase, which interconverts L-arabinose and L-ribulose araB, L-ribulokinase, which uses ATP to phosphorylate L-ribulose at C-5 araD, L-ribulose 5-phosphate epimerase, which interconverts L-ribulose 5-phosphate and L-xylulose 5-phosphate talB, transaldolase and tktA, transketolase. 

L-Arabinose isomerase has been purified from Escherichia coli. The enzyme catalyzes the isomerization of L-arabinose to L-ribulose by a proton transfer mechanism in contrast to xylose isomerase which uses a hydride transfer mechanism to perform a similar isomerization [20], This enzyme has high substrate specificity for L-arabinose, and its catalytic activity is dependent on manganese(II). It has been shown, however, that the enzyme could catalyze the exchange of the proton attached to C2 of arabinose with the solvent even in the absence of metal ion [20],... 

In Escherichia coli, L-arabinose isomerase (ECAI) catalyzes the isomerization of L-arabinose to L-ribulose. This enzyme is also of commercial interest as it catalyzes the conversion of D-galactose to D-tagatose in vitro. The crystal stmcture of ECAI was solved and refined at 2.6 angstrom resolution [152]. 

P. Kim, S. H. Yoon, H. J. Roh, and J. H. Choi, High production of D-tagatose, a potential sugar substitute, using immobilized L-arabinose isomerase, Biotechnol. Prog., 17 (2001) 208-210. 

Kim, R, Current studies on biological tagatose production using L-arabinose isomerase A review and future perspective, Appl. Microbiol. Biotechnol., 65, 243, 2004. 

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