title: Production of L-xylose from L-xylulose using Escherichia coli L-fucose isomerase.
abstract: L-Xylulose was used as a raw material for the production of L-xylose with a recombinantly produced Escherichia coli L-fucose isomerase as the catalyst. The enzyme had a very alkaline pH optimum (over 10.5) and displayed Michaelis-Menten kinetics for L-xylulose with a K(m) of 41 mM and a V(max) of 0.23 μmol/(mg min). The half-lives determined for the enzyme at 35 °C and at 45 °C were 6h 50 min and 1h 31 min, respectively. The reaction equilibrium between L-xylulose and L-xylose was 15:85 at 35 °C and thus favored the formation of L-xylose. Contrary to the L-rhamnose isomerase catalyzed reaction described previously [14]L-lyxose was not detected in the reaction mixture with L-fucose isomerase. Although xylitol acted as an inhibitor of the reaction, even at a high ratio of xylitol to L-xylulose the inhibition did not reach 50%.
authors: Department of Biotechnology and Chemical Technology, Aalto University, P.O. Box 6100, FIN-02015 Espoo, Finland. anne.usvalampi@aalto.fi
authors: Anne
authors: A
authors: Usvalampi
authors: Ossi
authors: O
authors: Turunen
authors: Jarkko
authors: J
authors: Valjakka
authors: Ossi
authors: O
authors: Pastinen
authors: Matti
authors: M
authors: Leisola
authors: Antti
authors: A
authors: Nyyssölä
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D007536:Isomerism; D007700:Kinetics; D008958:Models, Molecular; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014993:Xylitol / Q000494:pharmacology; D014994:Xylose / Q000096:biosynthesis*; D014996:Xylulose / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D014996:Xylulose; D014994:Xylose; D019747:Aldose-Ketose Isomerases; C019714:D-arabinose isomerase; D014993:Xylitol