69975-90-2Relevant academic research and scientific papers
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.
Thermostable transketolase from Geobacillus stearothermophilus: Characterization and catalytic properties
Abdoul-Zabar, Juliane,Sorel, Isabelle,Helaine, Virgil,Charmantray, Franck,Devamani, Titu,Yi, Dong,De Berardinis, Veronique,Louis, Dominique,Marliere, Philippe,Fessner, Wolf-Dieter,Hecquet, Laurence
, p. 116 - 128 (2013/03/13)
Here we have characterized the first transketolase (TK) from a thermophilic microorganism, Geobacillus stearothermophilus, which was expressed from a synthetic gene in Escherichia coli. The G. stearothermophilus TK (mTK gst) retained 100% activity for one week at 50 °C and for 3 days at 65 °C, and has an optimum temperature range around 60-70 °C, which will be useful for preparative applications and for future biocatalyst development. The thermostability of the mTKgst allowed us to carry out an easy, one-step purification by heat shock treatment of crude cell extracts at 65 °C for 45min, directly yielding 132mg of pure mTK gst from 1L of culture. The reaction rate of mTKgst with glycolaldehyde was 14 times higher at 70 °C than at 20 °C, and 4 times higher at 50 °C when compared to E. coli TK under identical conditions. When tested at 50 °C with other aldehydes as acceptors, mTKgst activity was approximately 3 times higher than those obtained at 20 °C. Applications of this new TK in biocatalysis were performed with hydroxypyruvate as donor and three different aldehydes as acceptors-glycolaldehyde, D-glyceraldehyde and butyraldehyde-from which the corresponding products L-erythrulose 1, D-xylulose 2 and 1,3-dihydroxyhexan-2-one 3 were obtained, respectively. The optical rotations for products 1 and 2 indicate that the stereospecificity of mTKgst is identical to that of other TK sources, leading to a (3S) configuration. With the non-hydroxylated substrate, butanal, the ee value was 85% (3S), showing higher enantioselectivity than the E. coli TK (75% ee, 3S). Processes at elevated temperatures could offer opportunities to extend the applications of TK biocatalysis, by favoring hydrophobic aldehyde acceptor substrate solubility and tolerance towards non-conventional media. Copyright
Efficient immobilization of yeast transketolase on layered double hydroxides and application for ketose synthesis
Benaissi, Karima,Helaine, Virgil,Prevot, Vanessa,Forano, Claude,Hecquet, Laurence
experimental part, p. 1497 - 1509 (2011/08/03)
Transketolase (TK) from S. cerevisiae was successfully immobilized on layered double hydroxides (LDH) using simple, affordable and efficient adsorption and coprecipitation based immobilization procedures. Optimization of the preparation was performed using zinc aluminium nitrate (Zn 2Al-NO3) and magnesium aluminium nitrate (Mg 2Al-NO3) LDH as immobilization supports, and the protein-to-LDH weight ratio (Q) was varied. The highest immobilization yields (98-99%) and highest relative specific activities (4.2-4.4 U·mg -1 for the immobilized enzyme compared to 4.5 U·mg -1 for the free enzyme) were both achieved when using a protein-to-LDH weight ratio (Q) of 0.38. Efficient lyophilization of the LDH-TK bionanocomposites thus synthesized was proven to allow easy use and storage of the supported TK with no significant loss of activity over a three-month period. The kinetic parameters of the LDH-TK enzyme were comparable to those of the free TK. The LDH-TK enzyme was finally tested for the synthesis of L-erythrulose starting from hydroxypyruvate lithium salt (Li-HPA) and glycolaldehyde (GA) as substrates. L-erythrulose was characterized and obtained with an isolated yield of 56% similar to that obtained with free TK. The reusability of the LDH-TK biohybrid material was then investigated, and we found no loss of enzymatic activity over six cycles. Copyright
