- Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of v-cyclodextrin
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Monosubstituted derivatives of γ-cyclodextrin (γ-CD) are suitable building blocks for supramolecular polymers, and can also serve as precursors for the synthesis of other regioselectively monosubstituted γ-CD derivatives. We prepared a set of monosubstituted 2I-O-, 3I-O-, and 6I-O-(3-(naphthalen-2-yl)prop-2-en-1-yl) derivatives of γ-CD using two different methods. A key step of the first synthetic procedure is a cross-metathesis between previously described regioisomers of mono-O-allyl derivatives of γ-CD and 2-vinylnaphthalene which gives yields of about 16-25% (2-5% starting from γ-CD). To increase the overall yields, we have developed another method, based on a direct alkylation of γ-CD with 3-(naphthalen-2-yl)allyl chloride as the alkylating reagent. Highly regioselective reaction conditions, which differ for each regioisomer in a used base, gave the monosubstituted isomers in yields between 12-19%. Supramolecular properties of these derivatives were studied by DLS, ITC, NMR, and Cryo-TEM.
- Bláhová, Markéta,Filippov, Sergey K.,Ková?ik, Lubomír,Horsky, Ji?í,Hybelbauerová, Simona,Syrová, Zdenka,K?í?ek, Tomá?,Jind?ich, Jind?ich
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- A spectroscopic study of the inclusion of azulene by β- And γ-cyclodextrins
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The inclusion of azulene (AZ) inside the cavities of β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) was studied using absorption, fluorescence and induced-circular dichroism spectroscopy. The inclusion of AZ into the cavity of β-CD has a stoichiometry of 1:1, whereas that of AZ/γ-CD complex is 1:2. The equilibrium constants for the formation of the two complexes were calculated to be 780 ± 150 M-1 for AZ:β-CD and (4.5 ± 0.86) × 105 M-2 for AZ:(γ-CD)2. The latter is due to a stepwise equilibrium mechanism in which a 1:1 complex is formed with a binding constant of 775 M -1, followed by the formation of a 1:2 complex with a binding constant of 580 M-1. The difference between the two binding constant values is slight, indicating an almost equal contribution from each of the γ-CD molecules to the overall binding in AZ:(γ-CD)2. From the induced-circular dichroism spectra, the inclusion of AZ was found to be axial in AZ:β-CD and nearly axial in AZ:(γ-CD)2.
- Abou-Zied, Osama K.
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- A novel cyclodextrin glucanotransferase from alkaliphilic Bacillus pseudalcaliphilus 20RF: Purification and properties
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A new cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) from the obligated alkaliphile Bacillus pseudalcaliphilus 20RF, isolated from Bulgarian soils, was purified up to 18-fold by ultrafiltration and starch adsorption with a recovery of 63% activity. The enzyme was a monomer with a molecular weight 70 kDa estimated by SDS-PAGE. The CGTase exhibited two pH optima at pH 6.0 and 9.0 and was optimally active at 60 °C. The enzyme could be effectively used for conversion of raw starch into cyclodextrins (CDs) in a wide pH range, from 5.0 to 10.0 and temperatures 60-70 °C. The enzyme was more heat resistant after its pretreatment in alkaline pH 9.0 at high temperatures 65-70 °C, than at pH 6.0 under the same reaction conditions. The CGTase showed a significant stability in the presence of 15 mM various metal ions and reagents after 30 min incubation at 25 °C. The purified CGTase could be used for an efficient cyclodextrin production without any additives which is of an industrial interest. The achieved high conversion of an insoluble raw commercial corn starch into cyclodextrins (47%) with production of only two types of cyclodextrins, β- and γ-CD (80%:20%) in alkaline pH 9.0, makes B. pseudalcaliphilus 20RF CGTase industrially desired for cyclodextrin manufacture.
- Atanasova, Nikolina,Kitayska, Tsvetina,Bojadjieva, Ivanka,Yankov, Dragomir,Tonkova, Alexandra
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- Enzyme-mediated dynamic combinatorial chemistry allows out-of-equilibrium template-directed synthesis of macrocyclic oligosaccharides
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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.
- Larsen, Dennis,Beeren, Sophie R.
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p. 9981 - 9987
(2019/11/14)
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- Altered product specificity of a cyclodextrin glycosyltransferase by molecular imprinting with cyclomaltododecaose
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Cyclodextrin glycosyltransferases (CGTases), members of glycoside hydrolase family 13, catalyze the conversion of amylose to cyclodextrins (CDs), circular α-(1,4)-linked glucopyranose oligosaccharides of different ring sizes. The CD containing 12 α-D-gluc
- Kaulpiboon, Jarunee,Pongsawasdi, Piamsook,Zimmermann, Wolfgang
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experimental part
p. 480 - 485
(2011/12/02)
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- Effects of ionic surfactants and cyclodextrins on hydride-transfer reaction of l-Benzyl-l,4-dihydronicotinamide with methylene blue
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The kinetics of the hydride-transfer reaction between methylene blue (MB+) and 1 -benzyl-1,4-dihydronictinamide (BNAH) were studied in media containing cyclodextrins (β- and γ-CD) and surfactants (sodium dodecyl sulfate (SDS), dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide). Cationic surfactants decreased the apparent first-order rate constant (k obsd) above the cmc, while SDS increased kobsd just above the cmc and then decreased kobsd with increasing surfactant concentration. This behavior for cationic surfactants was typical of micellar effects due to a separation of the reactants by the micelles. BNAH associated with micelles, whereas MB+ ions were repelled from the cationic interface of the micelles. Binding of BNAH and MB to the same SDS micelle enhanced the reaction, but dilution of reagents within the micellar interface with the increase in [SDS] caused a decrease in Kobsd. In β-CD-cationic surfactant mixtures, the results were interpreted in terms of the model which takes into account the formation of CD-BNAH, CD-MB+, and CD-surfactant complexes and the association of BNAH with micelles. The decrease in Kobsd with increasing surfactant concentration observed in γ-CD-cationic surfactant mixtures can be explained by the decrease in the concentration of free γ-CD by the formation of 1:1 and 2:1 complexes of surfactant monomer with β-CD.
- Matsumoto, Takeshi,Liu, Yingjin,Sueishi, Yoshimi,Yamamoto, Shunzo
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experimental part
p. 1383 - 1390
(2009/06/19)
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- Optimized synthesis of specific sizes of maltodextrin glycosides by the coupling reactions of Bacillus macerans cyclomaltodextrin glucanyltransferase
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Bacillus macerans cyclomaltodextrin glucanyltransferase (CGTase, EC 2.4.1.19), in reaction with cyclomaltohexaose and methyl α-d- glucopyranoside, methyl β-d-glucopyranoside, phenyl α-d- glucopyranoside, and phenyl β-d-glucopyranoside gave four kinds of maltodextrin glycosides. The reactions were optimized by using different ratios of the individual d-glucopyranosides to cyclomaltohexaose, from 0.5 to 5.0, to obtain the maximum molar percent yields of products, which were from 68.3% to 78.6%, depending on the particular d-glucopyranoside, and also to obtain different maltodextrin chain lengths. The lower ratios of 0.5-1.0 gave a wide range of sizes from d.p. 2-17 and higher. As the molar ratio was increased from 1.0 to 3.0, the larger sizes, d.p. 9-17, decreased, and the small and intermediate sizes, d.p. 2-8, increased; as the molar ratios were increased further from 3.0 to 5.0, the large sizes completely disappeared, the intermediate sizes, d.p. 4-8, decreased, and the small sizes, d.p. 2 and 3 became predominant. A comparison is made with the synthesis of maltodextrins by the reaction of CGTase with different molar ratios of d-glucose to cyclomaltohexaose.
- Yoon, Seung-Heon,Robyt, John F.
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p. 210 - 217
(2007/10/03)
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- Dynamics for the assembly of pyrene-γ-cyclodextrin host-guest complexes
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Pyrene and γ-cyclodextrin (γ-CD) form complexes with 1:1, 1:2, and 2:2 (pyrene/CD) stoichiometries. The complexation dynamics was studied using stopped flow. The dynamics for the higher-order complexes (1:2 and 2:2) occurs in the millisecond time domain, which contrasts with the much faster dynamics for the 1:1 complex. When pyrene is mixed with γ-CD, a transient enhancement of the concentration for the 2:2 complex was observed between 0.2 and 1 s, which at longer times leads to the formation of the 1:2 complex. This enhancement of the nonthermodynamic product is an example of the kinetic formation of a host-guest complex, and these types of processes may be explored to build self-assemblies under kinetic control.
- Dyck, Andria S.M.,Kisiel, Ursula,Bohne, Cornelia
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p. 11652 - 11659
(2007/10/03)
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- Isolation of Paenibacillus illinoisensis that produces cyclodextrin glucanotransferase resistant to organic solvents.
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A bacterium that secreted cyclodextrin glucanotransferase (CGTase) in a medium overlaid with n-hexane was isolated and identified as Paenibacillus illinoisensis strain ST-12 K. The CGTase of the strain was purified from the culture supernatant. The molecular mass was 70 kDa. The enzyme was stable at pH 6 to 10 and active at pH 5.0 to 8.0. The optimum temperature at pH 7.0 was 65 degrees C in the presence of 5 mM CaCl2. The enzyme produced mainly beta-cyclodextrin. The total yield of alpha-, beta-, and gamma- cyclodextrins was increased 1.4-fold by the addition of ethanol. In particular, the yield of beta-cyclodextrins in the presence of 10% (vol/vol) ethanol was 1.6-fold that without ethanol. The CGTase was stable and active in the presence of large amounts of various organic solvents.
- Doukyu, Noriyuki,Kuwahara, Hirokazu,Aono, Rikizo
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p. 334 - 340
(2007/10/03)
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- Catalysis of ester aminolysis by cyclodextrins. The reaction of alkylamines with p-nitrophenyl alkanoates
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The effects of four cyclodextrins (α-CD, β-CD, hydroxypropyl-β-CD, and γ-CD) on the aminolysis of p-nitrophenyl alkanoates (acetate to heptanoate) by primary amines (n-propyl to n-octyl, isobutyl, isopentyl, cyclopentyl, cyclohexyl, benzyl) in aqueous solution have been investigated. Rate constants for amine attack on the free and CD-bound esters (k(N) and k(cN)) have ratios (k(cN)/k(N)) varying from 0.08 (retardation) to 180 (catalysis). For the kinetically equivalent process of free ester reacting with CD-bound amine (k(Nc)), the ratios k(Nc)/k(N) vary from 0.2 to 28. Either way, there is evidence of catalysis in some cases and retardation in others. Changes in reactivity parameters with structure indicate more than one mode of transition state binding to the CDs. Short esters react with short alkylamines by attack of free amine on the ester bound by its aryl group, but for longer amines, free ester reacts with CD-bound amine. Reaction of long esters with long amines, which is catalyzed by β-CD and γ-CD, involves inclusion of the alkylamino group and possibly the ester acyl group. The larger cavity of γ-CD may allow the inclusion of the ester aryl group, as well as the alkylamino group, in the transition state. Reaction between an ester bound to the CD by its acyl group and free amine appears not to be important.
- Gadosy,Boyd,Tee
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p. 6879 - 6889
(2007/10/03)
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- Suitability and limitations of methods for characterisation of activity of malto-oligosaccharide-forming amylases
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The suitability and limitations of essential methods and reference substrates used for characterisation of activity of amylolytic enzymes is investigated. Saccharogenic, chromogenic and chromatographic methods are included. The results are discussed in relation to the measurement of reaction rates, determination of action mode and product specificity and the impact on identification and nomenclature of malto-oligosaccharide-forming amylases. An accurate determination of reaction rates using the saccharogenic methods strongly depends on the degree of polymerisation (DP) of the standards used and the hydrolysis products formed by the amylase. Particularly the use of glucose as standard can lead to overestimates due to the differences in the reducing potential of glucose and malto-oligosaccharides. The reliability of the chromogenic methods for determination of action mode depends on the DP of the substrate and the specificity of the amylase. For a characterisation of the starch hydrolysis products and the variation in the DP during hydrolysis, high performance anion-exchange chromatography with pulsed amperometric detection provided a fast and reliable method. A literature survey revealed varying and inconsistent use of nomenclature of malto-oligosaccharide forming amylases. Therefore a systematic approach identifying three main classes of activity is suggested using not only the mode of action and the DP of the major product but also the stage of hydrolysis at which this product is formed. (C) 2000 Elsevier Science Ltd.
- Duedahl-Olesen, Lene,Haastrup Pedersen, Lars,Lambertsen Larsen, Kim
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p. 109 - 119
(2007/10/03)
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- Influence of cyclodextrins on the fluorescence of some short and long chain linked flexible bisbenzenes in aqueous solution
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The UV absorption, induced circular dichroism (icd) spectra, steady state and time resolved fluorescence emission of the flexible bisbenzenes 1-4 were obtained in aqueous solution and in presence of α-, β-, and γ-cyclodextrin (CD). Bisbenzenes 1 and 2 in an aqueous environment exhibit a dual emission which is differently affected by the CDs. The long-wavelength emission is quenched by α- and β-CD and enhanced by γ-CD. This is due to the formation of inclusion complexes between the CDs and 1 (2) in the ground state, in agreement with the modifications of the UV spectrum and the appearance of icd signals. On the basis of these effects and of the influence of the CDs on the 1 and 2 lifetimes, the dual emission of these bisbenzenes is attributed to a set of different ground-state conformations.
- Bortolus, Pietro,Monti, Sandra,Smoluch, Miroslawa,Bouas-Laurent, Henri,Desvergne, Jean-Pierre
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p. 1165 - 1171
(2007/10/03)
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- Quantitative estimation of the bitter taste intensity of oxyphenonium bromide reduced by cyclodextrins from electromotive force measurements
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The bitter taste of oxyphenonium bromide, an antiacetylcholine drug, is suppressed by cyclodextrins. The extent of the suppression can be predicted from the electromotive force measurements with an oxyphenonium bromide- selective electrode. The relationship between the bitter taste intensity and the electromotive force holds true, regardless of the kind and concentration of natural and modified cyclodextrins. This result is explicable on the basis of the observation that both the bitter taste and the electric potential are determined by the concentration of free oxyphenonium bromide. Some implications and limitations of the present approach are discussed.
- Funasaki, Noriaki,Kawaguchi, Ryusaku,Ishikawa, Seiji,Hada, Sakae,Neya, Saburo,Katsu, Takashi
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p. 1733 - 1736
(2007/10/03)
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- Photochemistry of Benzophenone-Cyclodextrin Inclusion Complexes
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The photochemistry of benzophenone aqueous solutions in the presence of cyclodextrins (CDx) has been studied by stationary and pulsed techniques.Quenching of the phosphorescence is the consequence of hydrogen abstraction following the inclusion in the cyclodextrin cavity of the triplet benzophenone.The H-abstraction process has close analogies with the same reaction in micelles.Radical pair decay is controlled by the dimensions of the CDx cavity: intersystem crossing prevails in the presence of β-CDx, radical excit in the presence of α- and γ-CDx.The fate of the escaped radical also depends on the cavity dimensions, as revealed by the photoreduction quantum yields.
- Monti, Sandra,Flamigni, Lucia,Martelli, Alessandro,Bortolus, Pietro
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p. 4447 - 4451
(2007/10/02)
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- Cyclodextrin Inclusion Complexes of 1-Pyrenebutyrate: The Role of Coinclusion of Amphiphiles
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Several inclusion complexes with various stoichiometries are formed from 1-pyrenebutyrate ion (P) and the different cyclodextrins (α-, β-, and γ-CD).With α- and β-CD, the initially formed 1:1 complexes lead to the formation of 1:2 complexes (P*α2 and P*β2).As P can be only partially included in the small cavity of α-CD, the equilibrium constants for the formation of both complexes of α-CD are about an order of magnitude smaller than those of β-CD.For the same reason, P*β2, to which we assign a "barrel" configuration, is also an order of magnitude more effective than P*α2 in protecting singlet-excited P against quenching by triethanolamine.We had shown earlier that with γ-CD the 1:1 complex (P*γ) dimerizes to a 2:2 complex (P2*γ2), to which we also assigned a barrel configuration.The lack of efficient 1:2 complex formation in this case is attributed to the large size of the "barrel" enclosed by two γ-CD molecules.The extra space next to a single P molecule in such a cavity would have to be filled with water.However, the formation of a 1:2 inclusion complex between P and γ-CD can be induced by the coinclusion of a molecule with a hydrophobic moiety such as sodium hexanesulfonate (X).This replaces the water within the cavity and leads to the formation of P*X*γ2.This complex provides the highest degree of protection against quenching of excited P in these inclusion complexes.
- Herkstroeter, William G.,Martic, Peter A.,Evans, Ted R.,Farid, Samir
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p. 3275 - 3280
(2007/10/02)
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- Analysis of Static and Dynamic Host-Guest Associations of Detergents with Cyclodextrins via Photoluminiscence Methods
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Host-guest inclusion type associations between β- and γ-cyclodextrins (CD) and a series of cationic phosphorescence detergent probes (i.e., trimethylammonium bromide, alkyl = methyl (n=1, BNK-1+), pentyl (n=5, BNK-5+), and decyl (n=10, BNK-10+)) are reported.No evidence for association could be detected for α-CD.The association equilibrium constant (K), the association rate constant (kf), and the dissociation rate constant (kb) were evaluated from dynamic phosphorescence decay method by using Co(NH3)63+ as an aqueous-phase phosphorescence quencher.The kf values are of the order of 107 M-1 s-1 and are independent of the detergent structure.However, the magnitudes of kb and K vary over several orders of magnitude as a function of detergent and host structure.The results are discussed in terms of the importance of dehydration of CD and/or probe as a rate-determining step of inclusion.
- Turro, Nicholas J.,Okubo, Tsuneo,Chung, Chao-Jen
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p. 1789 - 1794
(2007/10/02)
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