69-79-4Relevant articles and documents
Redesign of the Active Site of Sucrose Phosphorylase through a Clash-Induced Cascade of Loop Shifts
Kraus, Michael,Grimm, Clemens,Seibel, Jürgen
, p. 33 - 36 (2016/01/15)
Sucrose phosphorylases have been applied in the enzymatic production of glycosylated compounds for decades. However, several desirable acceptors, such as flavonoids or stilbenoids, that exhibit diverse antimicrobial, anticarcinogenic or antioxidant properties, remain poor substrates. The Q345F exchange in sucrose phosphorylase from Bifidobacterium adolescentis allows efficient glucosylation of resveratrol, (+)-catechin and (-)-epicatechin in yields of up to 97 % whereas the wild-type enzyme favours sucrose hydrolysis. Three previously undescribed products are made available. The crystal structure of the variant reveals a widened access channel with a hydrophobic aromatic surface that is likely to contribute to the improved activity towards aromatic acceptors. The generation of this channel can be explained in terms of a cascade of structural changes arising from the Q345F exchange. The observed mechanisms are likely to be relevant for the design of other tailor-made enzymes.
Highly efficient room-temperature oxidation of cyclohexene and d-glucose over nanogold Au/SiO2 in water
Bujak, Piotr,Bartczak, Piotr,Polanski, Jaroslaw
, p. 15 - 21 (2013/01/14)
Silica-supported nanogold catalysts suspended in 30% hydrogen peroxide using ultrasound are highly active and selective for cyclohexene and d-glucose oxidation at room temperature. In these conditions a polar reactant, D-glucose, can be efficiently and directly converted with 100% yield using this system, while a conversion of apolar cyclohexene is limited by the addition of a surfactant improving cosolubility in the system and/or catalyst/support wettability. To our best knowledge this is the first time that hydrogen peroxide has been used efficiently in association with a gold catalyst for the selective oxidation of cyclohexene in a biphasic system.
Regioselective glucosylation of inositols catalyzed by Thermoanaerobacter sp. CGTase
Miranda-Molina, Alfonso,Marquina-Bahena, Silvia,Alvarez, Laura,Lopez-Munguia, Agustin,Castillo, Edmundo
, p. 93 - 101,9 (2020/08/20)
Monoglucosylated products of l-chiro-, d-chiro-, muco-, and allo-inositol were synthesized by regioselective α-d-glucosylation with cyclodextrin glucosyl transferase from Thermoanaerobacter sp. after hydrolysis of by products with Aspergillus niger glucoamylase. While the reactions carried out with d-chiro-, muco-, and allo-inositol resulted in the regioselective formation of monoglucosylated products, two products were obtained in the reaction with l-chiro-inositol. Through the structural characterization of the glucosylated inositols here we demonstrated that the selectivity observed in the glucosylation of several inositols by Thermoanaerobacter sp. CGTase, is analogous to the specificity observed for the glucosylation of β-d-glucopyranose and equivalent glucosides.
Bioengineering of Leuconostoc mesenteroides glucansucrases that gives selected bond formation for glucan synthesis and/or acceptor-product synthesis
Kang, Hee Kyoung,Kimura, Atsuo,Kim, Doman
experimental part, p. 4148 - 4155 (2011/10/30)
The variations in glucosidic linkage specificity observed in products of different glucansucrases appear to be based on relatively small differences in amino acid sequences in their sugar-binding acceptor subsites. Various amino acid mutations near active sites of DSRBCB4 dextransucrase from Leuconostoc mesenteroides B-1299CB4 were constructed. A triple amino acid mutation (S642N/E643N/V644S) immediately next to the catalytic D641 (putative transition state stabilizing residue) converted DSRBCB4 enzyme from the synthesis of mainly α-(1→6) dextran to the synthesis of α-(1→6) glucan containing branches of α-(1→3) and α-(1→4) glucosidic linkages. The subsequent introduction of mutation V532P/V535I, located next to the catalytic D530 (nucleophile), resulted in the synthesis of an α-glucan containing increased branched α-(1→4) glucosidic linkages (approximately 11%). The results indicate that mutagenesis can guide glucansucrase toward the synthesis of various oligosaccharides or novel polysaccharides with completely altered linkages without compromising high transglycosylation activity and efficiency.
APPLICATIONS OF BIOBASED GLYCOL COMPOSITIONS
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Page/Page column 11, (2008/06/13)
A biobased replacement for propylene glycol and ethylene glycol derived from petrochemical sources is presented. The product mixture from the hydrogenolysis of certain polyols from biobased renewable resources may replace propylene glycol and ethylene glycol products from petrochemical sources. Applications and methods of the biobased hydrogenolysis product mixture are disclosed. The compositions and methods provide a feedstock for industrial use which has a 13C/12C isotope ratio characteristic of bioderived material.
Pullulanase-Amylase Complex Enzyme from Bacillus subtilis
Takasaki, Yoshiyuki
, p. 9 - 16 (2007/10/02)
A novel pullulanase-amylase complex enzyme, which hydrolyzes pullulan into maltotriose as well as starch into maltose and maltotriose as the main products, was found in the culture filtrate of a strain of Bacillus subtilis newly isolated from soil.The enzyme was purified to almost complete homogeneity by means of calcium phosphate gel adsorption, DEAE-Sepharose column chromatography and Bio-gel A-1.5 m filtration.The optimum pH of the pullulanase activity was observed at around 7.0 to 7.5, with a discernible shoulder around pH 5.0.While the optimum pH of the amylase activity was 6 - 7.The optimum temperatures of the pullulanase and amylase activities were about 60 deg C and about 50 deg C, respectively.The molecular weight was estimated to be about 450,000 by the gel filtration method.The enzyme could be used for the production of glucose from starch with glucoamylase and the production of a new type of syrup containing a relatively high amount of maltotriose, 50 - 55 percent, from starch.
