Publications

• Mechanism of action of D-xylose isomerase.

  Asboth B., Naray-Szabo G.

  The present knowledge on the stereochemical mechanism of action of glucose (or xylose) isomerase, one of the highest tonnage industrial enzymes, is summarized. First we deal shortly with experimental methods applied to study the structure and function of this enzyme: enzyme kinetics, protein engin ... >> More

  The present knowledge on the stereochemical mechanism of action of glucose (or xylose) isomerase, one of the highest tonnage industrial enzymes, is summarized. First we deal shortly with experimental methods applied to study the structure and function of this enzyme: enzyme kinetics, protein engineering, X-ray crystallography, nuclear magnetic and electron paramagnetic resonance spectroscopy. Computational methods like homology modeling, molecular orbital, molecular dynamics and continuum electrostatic methods are also shortly treated. We discuss mostly those results and their contribution to the elucidation of the mechanism of action that have been published in the last decade. Structural characteristics of free xylose isomerase as well as its complexes with various ligands are depicted. This information provides a tool for the study of structural details of the enzyme mechanism. We present a general mechanism where the first step is ring opening, which is followed by the extension of the substrate to an open-chain conformation, a proton shuttle with the participation of a structural water molecule and the rate-determining hydride shift. The role of metal ions in the catalytic process is discussed in detail. Finally we present main trends in efforts of engineering the enzyme and delineate the prospective future lines. The review is completed by an extended bibliography with over 100 citations. << Less

  Curr Protein Pept Sci 1:237-254(2000) [PubMed] [EuropePMC]

• X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

  Carrell H.L., Glusker J.P., Burger V., Manfre F., Tritsch D., Biellmann J.-F.

  The structures of crystalline D-xylose isomerase (D-xylose ketol-isomerase; EC 5.3.1.5) from Streptomyces rubiginosus and of its complexes with substrate and with an active-site-directed inhibitor have been determined by x-ray diffraction techniques and refined to 1.9-A resolution. This study iden ... >> More

  The structures of crystalline D-xylose isomerase (D-xylose ketol-isomerase; EC 5.3.1.5) from Streptomyces rubiginosus and of its complexes with substrate and with an active-site-directed inhibitor have been determined by x-ray diffraction techniques and refined to 1.9-A resolution. This study identifies the active site, as well as two metal-binding sites. The metal ions are important in maintaining the structure of the active-site region and one of them binds C3-O and C5-O of the substrate forming a six-membered ring. This study has revealed a very close contact between histidine and C1 of a substrate, suggesting that this is the active-site base that abstracts a proton from substrate. The mechanism-based inhibitor is a substrate analog and is turned over by the enzyme to give a product that alkylates this same histidine, reinforcing our interpretation. The changes in structure of the native enzyme, the enzyme with bound substrate, and the alkylated enzyme indicate that the mechanism involves an "open-chain" conformation of substrate and that the intermediate in the isomerization reaction is probably a cis-ene diol because the active-site histidine is correctly placed to abstract a proton from C1 or C2 of the substrate. A water molecule binds to C1O and C2O of the substrate and so may act as a proton donor or acceptor in the enolization of a ring-opened substrate. << Less

  Proc. Natl. Acad. Sci. U.S.A. 86:4440-4444(1989) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Production of d-mannose from d-glucose by co-expression of d-glucose isomerase and d-lyxose isomerase in Escherichia coli.

  Huang J., Yu L., Zhang W., Zhang T., Guang C., Mu W.

  <h4>Background</h4>d-Mannose is not only the epimer of d-glucose at the C-2 position, but also the aldose isomer of d-fructose. Because of its physiological properties and health benefits, d-mannose has attracted public interest. It has been confirmed that d-mannose has broad applications in food, ... >> More

  <h4>Background</h4>d-Mannose is not only the epimer of d-glucose at the C-2 position, but also the aldose isomer of d-fructose. Because of its physiological properties and health benefits, d-mannose has attracted public interest. It has been confirmed that d-mannose has broad applications in food, cosmetics, and pharmaceutical industries. According to the Izumoring strategy, d-glucose isomerase (d-GI) and d-lyxose isomerase (d-LI) play important roles in the conversions of d-fructose from d-glucose and of d-mannose from d-fructose respectively. In this study, a one-step enzyme process of d-mannose production from d-glucose has been constructed by co-expression of the d-GI from Acidothermus cellulolyticus and d-LI from Thermosediminibacter oceani in Escherichia coli BL21(DE3) cells.<h4>Results</h4>The co-expression system exhibits maximum activity at pH 6.5 and 65 °C with Co²⁺ supplement. It is relatively thermostable at less than 65 °C. When the reaction reaches equilibrium, the ratio of d-glucose, d-fructose, and d-mannose is approximately 34 : 49.6 : 16.4. By using this co-expression system, about 60.0 g L^-1 d-mannose is obtained from 400 g L^-1 d-glucose in 8 h.<h4>Conclusion</h4>This co-expression of d-GI and d-LI system provides a novel and efficient approach for d-mannose production. © 2018 Society of Chemical Industry. << Less

  J Sci Food Agric 98:4895-4902(2018) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Anomeric specificity and mechanism of two pentose isomerases.

  Schray K.J., Rose I.A.

  Biochemistry 10:1058-1062(1971) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Switching substrate preference of thermophilic xylose isomerase from D-xylose to D-glucose by redesigning the substrate binding pocket.

  Meng M., Lee C., Bagdasarian M., Zeikus J.G.

  The substrate specificity of thermophilic xylose isomerase from Clostridium thermosulfurogenes was examined by using predictions from the known crystal structure of the Arthrobacter enzyme and site-directed mutagenesis of the thermophile xylA gene. The orientation of glucose as a substrate in the ... >> More

  The substrate specificity of thermophilic xylose isomerase from Clostridium thermosulfurogenes was examined by using predictions from the known crystal structure of the Arthrobacter enzyme and site-directed mutagenesis of the thermophile xylA gene. The orientation of glucose as a substrate in the active site of the thermophilic enzyme was modeled to position the C-6 end of hexose toward His-101 in the substrate-binding pocket. The locations of Met-87, Thr-89, Val-134, and Glu-180, which contact the C-6-OH group of the substrate in the sorbitol-bound xylose isomerase from Arthrobacter [Collyer, C.A., Henrick, K. & Blow, D. M. (1990) J. Mol. Biol. 212, 211-235], are equivalent to those of Trp-139, Thr-141, Val-186, and Glu-232 in the thermophilic enzyme. Replacement of Trp-139 with Phe reduced the Km and enhanced the kcat of the mutant thermophilic enzyme toward glucose, whereas this substitution reversed the effect toward xylose. Replacement of Val-186 with Thr also enhanced the catalytic efficiency of the enzyme toward glucose. Double mutants with replacements Trp-139----Phe/Val-186----Thr and Trp-139----Phe/Val-186----Ser had a higher catalytic efficiency (kcat/Km) for glucose than the wild-type enzyme of 5- and 2-fold, respectively. They also exhibited 1.5- and 3-fold higher catalytic efficiency for D-glucose than for D-xylose, respectively. These results provide evidence that alteration in substrate specificity of factitious thermophilic xylose isomerases can be achieved by designing reduced steric constraints and enhanced hydrogen-bonding capacity for glucose in the substrate-binding pocket of the active site. << Less

  Proc Natl Acad Sci U S A 88:4015-4019(1991) [PubMed] [EuropePMC]

• Role of the divalent metal ion in sugar binding, ring opening, and isomerization by D-xylose isomerase: replacement of a catalytic metal by an amino acid.

  Allen K.N., Lavie A., Glasfeld A., Tanada T.N., Gerrity D.P., Carlson S.C., Farber G.K., Petsko G.A., Ringe D.

  The distinct roles of the two magnesium ions essential to the activity of D-xylose isomerase from Streptomyces olivochromogenes were examined. The enzyme-magnesium complex was isolated, and the stoichiometry of cation binding determined by neutron activation analysis to be 2 mol of magnesium per m ... >> More

  The distinct roles of the two magnesium ions essential to the activity of D-xylose isomerase from Streptomyces olivochromogenes were examined. The enzyme-magnesium complex was isolated, and the stoichiometry of cation binding determined by neutron activation analysis to be 2 mol of magnesium per mole of enzyme. A plot of Mg2+ added versus Mg2+ bound to enzyme is consistent with apparent KD values of < or = 0.5-1.0 mM for one Mg2+ and < or = 2-5 mM for the second. A site-directed mutant of D-xylose isomerase was designed to remove the tighter, tetracoordinated magnesium binding site (site 1, Mg-1); Glu180 was replaced with Lys180. The stoichiometry of metal binding to this mutant, E180K, is 1 mol of magnesium per mole of enzyme. Ring-opening assays with 1-thioglucose (H2S released upon ring opening) show E180K catalyzes the opening of the sugar ring at 20% the rate of the wild-type, but E180K does not catalyze isomerization of glucose to fructose. Thus, the magnesium bound to Glu180 is essential for isomerization but not essential for ring opening. The X-ray crystallographic structures of E180K in the absence of magnesium and in the presence and absence of 250 mM glucose were obtained to 1.8-A resolution and refined to R factors of 17.7% and 19.7%, respectively. The wild-type and both E180K structures show no significant structural differences, except the epsilon-amino group of Lys180, which occupies the position usually occupied by the Mg-1.(ABSTRACT TRUNCATED AT 250 WORDS) << Less

  Biochemistry 33:1488-1494(1994) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.