|Gene:||lxrA||Accession Number: G-12471 (MetaCyc)|
Species: Aspergillus niger
Subunit composition of
L-xylulose reductase = [LxrA]8
L-xylulose reductase subunit = LxrA
Recombinant enzyme was expressed in Saccharomyces cerevisiae, purified as a His-tagged protein, and characterized [Mojzita10].
The relative molecular mass of the L-xylulose reductase subunit was determined by SDS-PAGE [Witteveen94].
Molecular Weight of Polypeptide: 32 kD (experimental) [Witteveen94 ]
Molecular Weight of Multimer: 250 kD (experimental) [Witteveen94]
Enzymatic reaction of: L-xylulose reductase
Synonyms: xylitol dehydrogenase, xylitol:NADP+ 4-oxidoreductase (L-xylulose-forming)
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
This reaction is reversible. [Seiboth07]
The pH optimum of the reductase (forward) reaction was described as around 6.5 and broad. The enzyme was highly specific for L-xylulose in the forward direction and for xylitol in the reverse (oxidative) direction. A low level of activity was found with the substrates D-xylulose, D-erythrose and dihydroxyacetone in the forward direction, and with D-sorbitol in the reverse direction. It was also highly specific for NADPH and no activity was found with NADH. [Witteveen94]
Product inhibition was observed. The enzyme showed competitive inhibition by NADPH relative to NADP+ and vice versa. Xylitol inhibited at very high concentration. L-xylulose inhibited, but the assay accuracy was too low to determine the inhibition type. [Witteveen94]
pH(opt): 6.5 [Witteveen94]
Mojzita10: Mojzita D, Vuoristo K, Koivistoinen OM, Penttila M, Richard P (2010). "The 'true' L-xylulose reductase of filamentous fungi identified in Aspergillus niger." FEBS Lett 584(16);3540-4. PMID: 20654618
Seiboth07: Seiboth B, Gamauf C, Pail M, Hartl L, Kubicek CP (2007). "The D-xylose reductase of Hypocrea jecorina is the major aldose reductase in pentose and D-galactose catabolism and necessary for beta-galactosidase and cellulase induction by lactose." Mol Microbiol 66(4);890-900. PMID: 17924946
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