3019-74-7Relevant academic research and scientific papers
The crystal structure of human transketolase and new insights into its mode of action
Mitschke, Lars,Parthier, Christoph,Schroeder-Tittmann, Kathrin,Coy, Johannes,Luedtke, Stefan,Tittmann, Kai
, p. 31559 - 31570 (2010)
The crystal structure of human transketolase (TKT), a thiamine diphosphate (ThDP) and Ca2+-dependent enzyme that catalyzes the interketol transfer between ketoses and aldoses as part of the pentose phosphate pathway, has been determined to 1.75 A resolution. The recombinantly produced protein crystallized in space group C2 containing one monomer in the asymmetric unit. Two monomers form the homodimeric biological assembly with two identical active sites at the dimer interface. Although the protomer exhibits the typical three (α/β)-domain structure and topology reported for TKTs from other species, structural differences are observed for several loop regions and the linker that connects the PP and Pyr domain. The cofactor and substrate binding sites of human TKT bear high resemblance to those of other TKTs but also feature unique properties, including two lysines and a serine that interact with the β-phosphate of ThDP. Furthermore, Gln189 spans over the thiazolium moiety of ThDP and replaces an isoleucine found in most non-mammalian TKTs. The side chain of Gln428 forms a hydrogen bond with the 4′-amino group of ThDP and replaces a histidine that is invariant in all non-mammalian TKTs. All other amino acids involved in substrate binding and catalysis are strictly conserved. Besides a steady-state kinetic analysis, microscopic equilibria of the donor half-reaction were characterized by an NMR-based intermediate analysis. These studies reveal that formation of the central 1,2-dihydroxyethyl-ThDP carbanion-enamine intermediate is thermodynamically favored with increasing carbon chain length of the donor ketose substrate. Based on the structure of human transketolase and sequence alignments, putative functional properties of the related transketolase-like proteins TKTL1 and -2 are discussed in light of recent findings suggesting that TKTL1 plays a role in cancerogenesis.
Development of screening methods for transketolase activity and substrate scope
Ranoux, Adeline,Arends, Isabel W.C.E.,Hanefeld, Ulf
, p. 790 - 793 (2012)
A new GC-based method is developed for the screening of activity and stereoselectivity of a wide range of polyols as substrates of transketolase (TK). Compared to previous screening methods, it shows higher reproducibility, sensitivity and range of detection. In combination with HPLC screening, it can be used efficiently to test mutant libraries obtained by directed evolution methods.
An efficient synthesis of sedoheptulose catalyzed by spinach transketolase
Dalmas,Demuynck
, p. 1169 - 1172 (1993)
A practical procedure for transketolase catalyzed condensation of hydropyruvic acid with D-ribose has been used for the synthesis of D-sedoheptulose.
One-Pot Cascade Synthesis of (3S)-Hydroxyketones Catalyzed by Transketolase via Hydroxypyruvate Generated in Situ from d-Serine by d-Amino Acid Oxidase
L'enfant, Mélanie,Bruna, Felipe,Lorillière, Marion,Ocal, Nazim,Fessner, Wolf-Dieter,Pollegioni, Loredano,Charmantray, Franck,Hecquet, Laurence
, p. 2550 - 2558 (2019/04/17)
We described an efficient in situ generation of hydroxypyruvate from d-serine catalyzed by a d-amino acid oxidase from Rhodotorula gracilis. This strategy revealed an interesting alternative to the conventional chemical synthesis of hydroxypyruvate starting from toxic bromopyruvate or to the enzymatic transamination from l-serine requiring an additional substrate as amino acceptor. Hydroxypyruvate thus produced was used as donor substrate of transketolases from Escherichia coli or from Geobacillus stearothermophilus catalyzing the stereoselective formation of a carbon?carbon bond. The enzymatic cascade reaction was performed in one-pot in the presence of d-serine and appropriate aldehydes for the synthesis of valuable (3S)-hydroxyketones, which were obtained with high enantio- and diastereoselectivity and in good yield. The efficiency of the process was based on the irreversibility of both reactions allowing complete conversion of d-serine and aldehydes. (Figure presented.).
Chiral Polyol Synthesis Catalyzed by a Thermostable Transketolase Immobilized on Layered Double Hydroxides in Ionic liquids
Ali, Ghina,Moreau, Thomas,Forano, Claude,Mousty, Christine,Prevot, Vanessa,Charmantray, Franck,Hecquet, Laurence
, p. 3163 - 3170 (2015/10/19)
In this work we set out to study the activity of a thermostable Transketolase (TK) from Geobacillus stearothermophilus (TKgst) in an ionic liquid as cosolvent, which has never been investigated before with this enzyme. 1-Butyl-3-methylimidazolium chloride ([BMIm][Cl]) in the range 30-50% in water maintained the total activity of TKgst and increased the reaction rate in the presence of pentoses as acceptor substrates, particularly d-ribose. To improve the synthetic process, TKgst was immobilized on an inorganic support, layered double hydroxides (LDHs), with excellent immobilization yield and catalytic activity using a simple, eco-compatible, efficient coprecipitation procedure. The biohybrid MgAl@TKgst was tested in 30% [BMIm][Cl] for the synthesis of a rare, very costly commercially available sugar, d-sedoheptulose, which was obtained in one step from d-ribose with an isolated yield of 82%. This biohybrid was reusable over four cycles with no loss of enzymatic activity. The particular activity of free and immobilized TKgst in [BMIm][Cl] holds promise to extend the applications of TKgst in other ionic liquids and unusual media in biocatalysis.
Synthesis of sedoheptulose from 2-C-(hydroxymethyl)-D-allose by molybdic acid-catalysed carbon-skeleton rearrangement
Hricoviniova-Bilikova, Zuzana,Petrus, Ladislav
, p. 31 - 36 (2007/10/03)
A new branched-chain aldose, 2-C-(hydroxymethyl)-D-allose (3), was obtained by a base-catalysed addition of 2,3:5,6-di-O-isopropylidene-β-D-allofuranose to formaldehyde followed by acid hydrolysis of the aldol product. On treatment with a catalytic amount of molybdic acid at 90°C, 3 afforded its equilibrium mixture with sedoheptulose tautomeric and anhydro forms in the ratio 12:1. Sedoheptulose in its 2,7-anhydro form, 2,7-anhydro-β-D-altro-heptulopyranose, was obtained from this mixture by treatment with 0.5 M H2SO4 and crystallisation (overall 63% yield). Copyright (C) 1999 Elsevier Science Ltd.
ENZYME-CATALYZED SYNTHESIS OF CARBOHYDRATES: SYNTHETIC POTENTIAL OF TRANSKETOLASE
Demuynck, Colette,Bolte, Jean,Hecquet, Laurence,Dalmas, Valerie
, p. 5085 - 5088 (2007/10/02)
The synthetic potential of yeast or spinach transketolases was studied, using hydroxypyruvate as a donor substrate and 31 aldehydes as acceptors.All of them react, including aromatic, heteroaromatic and α,β unsaturated aldehydes.
SYNTHESIS OF SEDOHEPTULOSE FROM NON-DIALYZABLE, ENDOGENOUS SUBSTRATES IN MAMMALIAN TISSUE EXTRACTS
Hipps, Paul P.,Ackermann, Karen,Holland, William H.,Sherman, William R.
, p. 1 - 6 (2007/10/02)
Sedoheptulose was observed to be formed at the rate of 12-120 nmol/g tissue/h in dialyzed rat and bovine tissue homogenates.The compound was identified by its gas-chromatographic retention time and by its mass spectrum.A standard of -sedoheptulose was prepared from D-fructose 6-phosphate and D-erythrose 4-phosphate for use in radioactive gas-chromatographic analysis in studies of possible precursors of the sedoheptulose.The reaction was stimulated by NAD(1+).Evidence is presented to show that non-dialyzable sedoheptulose 7-phosphate may be the endogenous precursor.These results show that care must be exercised when using crude enzyme preparations and extremely sensitive analytical methods so that chromatographically unresolved products formed from non-dialyzable, endogenous substrates of low molecular weight do not introduce significant error in the analysis of the expected product.
