7585-39-9Relevant articles and documents
Synthesis and reactivity of 6-β-cyclodextrin monoaldehyde: An electrophilic cyclodextrin for the derivatization of macromolecules under mild conditions
Huff,Bieniarz
, p. 7511 - 7516 (1994)
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Effect of the reaction temperature on the transglycosylation reactions catalyzed by the cyclodextrin glucanotransferase from Bacillus macerans for the synthesis of large-ring cyclodextrins
Qi, Qingsheng,She, Xiaoyan,Endo, Tomohiro,Zimmermann, Wolfgang
, p. 799 - 806 (2004)
The synthesis of cyclodextrins with from 6 to more than 50 glucose units by cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from Bacillus macerans was investigated. Analysis of the synthesized cyclic α-1,4-glucan products showed that a higher yield of large-ring cyclodextrins were obtained with a reaction temperature of 60°C compared to 40°C. The yield of large-ring cyclodextrins obtained at 60°C represented about 50% of the total glucans employed in the reaction. Analysis of the cyclodextrin-forming cyclization reaction and of the coupling reaction of the CGTase resulting in the degradation of mainly the larger cyclic α-1,4-glucans indicated higher rates of the cyclization reaction at 60°C compared to 40°C while the opposite was found for the coupling reaction.
Photochromism of dithienylethenes included in cyclodextrins
Takeshita, Michinori,Kato, Nobuo,Kawauchi, Susumu,Imase, Tatsuya,Watanabe, Junji,Irie, Masahiro
, p. 9306 - 9313 (1998)
The effect of inclusion of diarylethenes in cyclodextrin cavities on cyclization quantum yields and on circular dichroism (CD) spectral changes by photoirradiation was studied. The addition of β-and γ-cyclodextrins to an aqueous solution of the open-ring form of 2,2'-dimethyl-3,3'-(perfluoro- cyclopentene-1,2-diyl)bis(benzo[b]thiophene-6-sulfonate) (1a) increased the ratio of the antiparallel conformation. The enrichment of antiparallel conformation caused an increase in the photocyclization quantum yield of 1a. The CD spectral intensity of the mixtures of 1a or 2,2'4,4'-tetramethyl- 3,3'-(perfluorocyclopentene-1,2-dyl)bis(thiophen-5-yl-(phenyl-4-sulfonate)) (2a) and cyclodextrins in aqueous solution increased with the increasing concentration of cyclodextrins. The induced CD spectrum of 1 in β- cyclodextrin reversibly changed from negative to positive by UV irradiation. The spectral change was attributed to the change in the direction of transition moment of 1 in the cavity.
Characterization of cyclodextrin glycosyltransferase immobilized on silica microspheres via aminopropyltrimethoxysilane as a spacer arm
Matte, Carla Roberta,Nunes, Michael Ramos,Benvenutti, Edilson Valmir,Schoeffer, Jessie Da Natividade,Ayub, Marco Antonio Zachia,Hertz, Plinho Francisco
, p. 51 - 56 (2012)
In this work, the enzymatic properties of immobilized cyclodextrin glycosyltransferase (CGTase) of Thermoanaerobacter sp. were investigated and compared with the soluble form of the enzyme. CGTase was immobilized on mesoporous silica microspheres synthesized using polyethylene glycol 400 as swelling agent, silanized with 3-aminopropyltrimethoxysilane (APTMS), and activated with glutaraldehyde prior to immobilization. This innovative approach for support preparation produced high yields of immobilization (83%) and activity recoveries (73%), which are the highest so far reported for CGTase. The soluble enzyme (CGTase) and its immobilized form (ImCGTase) showed similar values for the optimal pH activity, while optimal reaction temperatures were found to be 100 °C and 80 °C, respectively. The immobilized enzyme showed similar values for Km and thermal stabilities with the soluble form, while its Vmax was lower. The immobilized enzyme was tested in repeated batches in order to simulate recovery and reuse, keeping about 60% of the initial catalytic activity after 15 cycles, showing its good chemical and mechanical resistance.
Preservation of Bacillus firmus strain 37 and optimization of cyclodextrin biosynthesis by cells immobilized on loofa sponge
Pazzetto, Rubia,De Souza Ferreira, Sabrina Barbosa,Santos, Elder James Silva,Moriwaki, Cristiane,Guedes, Teresinha Aparecida,Matioli, Graciette
, p. 9476 - 9488 (2012)
The preservation of Bacillus firmus strain 37 cells by lyophilization was evaluated and response surface methodology (RSM) was used to optimize the β-cyclodextrin (β-CD) production by cells immobilized on loofa sponge. Interactions were studied with the variables temperature, pH and dextrin concentration using a central composite design (CCD). Immobilization time influence on β-CD production was also investigated. B. firmus strain 37 cells remained viable after one year of storage, showing that the lyophilization is a suitable method for preservation of the microorganism. From the three-dimensional diagrams and contour plots, the best conditions for β-CD production were determined: temperature 60 °C, pH 8, and 18% dextrin. Considering that the amount of dextrin was high, a new assay was carried out, in which dextrin concentrations of 10, 15, and 18% were tested and the temperature of 60 °C and pH 8 were maintained. The results achieved showed very small differences and therefore, for economic reasons, the use of 10% dextrin is suggested. Increasing the immobilization time of cells immobilized on synthetic sponge the β-CD production decreased and did not change for cells immobilized on loofa sponge. The results of this research are important for microorganism preservation and essential in the optimization of the biosynthesis of CD.
Chiral recognition for the complexation dynamics of β-cyclodextrin with the enantiomers of 2-naphthyl-1-ethanol
Tang, Hao,Sutherland, Andria S. M.,Osusky, Lana M.,Li, Yan,Holzwarth, Josef F.,Bohne, Cornelia
, p. 358 - 369 (2014)
The focus of this study is to understand the origin of the chiral recognition for a host-guest system containing complexes with different stoichiometries. Each enantiomer of 2-naphthyl-1-ethanol forms two different 1:1 complexes with β-cyclodextrin, leading to the formation of three different 2:2 complexes. One of these 2:2 complexes leads to excimer emission of the guest. Fluorescence studies were employed to determine the binding isotherms for the 1:1 and 2:2 complexes. No chiral discrimination was directly observed for the formation of the 1:1 complexes, while higher equilibrium constants (29% from binding isotherms and 40% from kinetic studies) were observed for the formation of the 2:2 complexes with (R)-2-naphthyl-1-ethanol when compared to the formation of the 2:2 complexes formed from (S)-2-naphthyl-1-ethanol. The relaxation kinetics was studied using stopped-flow experiments. The formation of the 2:2 complexes was followed by detecting the excimer emission from one of the 2:2 complexes. The relaxation kinetics was faster for (S)-2-naphthyl-1- ethanol, where a higher dissociation rate constant, by 47%, was observed, suggesting that the chiral discrimination occurs because the interaction between two cyclodextrins is more favorable for the complexes containing (R)-2-naphthyl-1-ethanol when compared to (S)-2-naphthyl-1-ethanol. The same overall equilibrium constants were observed for the 1:1 complexes with both enantiomers showing that at a given cyclodextrin concentration the sum of the two types of 1:1 complexes is the same for both enantiomers. However, analysis of the binding isotherms indicates that the ratio between the two different 1:1 complexes for each enantiomer was different for (R)- and (S)-2-naphthyl-1- ethanol. The Royal Society of Chemistry and Owner Societies.
DIBAL-H mediated triple and quadruple debenzylations of perbenzylated cyclodextrins
Rawal, Girish K.,Rani, Shikha,Ward, Sandra,Ling, Chang-Chun
, p. 171 - 180 (2010)
Diisobutylaluminium hydride (DIBAL-H) mediated reductive removal of benzyl groups was investigated for perbenzylated α-, β- and γ-cyclodextrins using DIBAL-H in hexane as the reagent. It was found that under the new conditions, the debenzylation can be better controlled to provide sequentially tri- and tetra-debenzylated products in moderate yields and in a regioselective manner. In the case of α-cyclodextrin, the removal of the third and fourth benzyl groups took a different path involving the secondary rim, compared to β- and γ-cyclodextrins which both gave only 6-O-debenzylated products. The Royal Society of Chemistry 2010.
Enzyme-mediated dynamic combinatorial chemistry allows out-of-equilibrium template-directed synthesis of macrocyclic oligosaccharides
Larsen, Dennis,Beeren, Sophie R.
, p. 9981 - 9987 (2019/11/14)
We show that the outcome of enzymatic reactions can be manipulated and controlled by using artificial template molecules to direct the self-assembly of specific products in an enzyme-mediated dynamic system. Specifically, we utilize a glycosyltransferase to generate a complex dynamic mixture of interconverting linear and macrocyclic α-1,4-d-glucans (cyclodextrins). We find that the native cyclodextrins (α, β and γ) are formed out-of-equilibrium as part of a kinetically trapped subsystem, that surprisingly operates transiently like a Dynamic Combinatorial Library (DCL) under thermodynamic control. By addition of different templates, we can promote the synthesis of each of the native cyclodextrins with 89-99% selectivity, or alternatively, we can amplify the synthesis of unusual large-ring cyclodextrins (δ and ?) with 9 and 10 glucose units per macrocycle. In the absence of templates, the transient DCL lasts less than a day, and cyclodextrins convert rapidly to short maltooligosaccharides. Templates stabilize the kinetically trapped subsystem enabling robust selective synthesis of cyclodextrins, as demonstrated by the high-yielding sequential interconversion of cyclodextrins in a single reaction vessel. Our results show that given the right balance between thermodynamic and kinetic control, templates can direct out-of-equilibrium self-assembly, and be used to manipulate enzymatic transformations to favor specific and/or alternative products to those selected in Nature.
