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Search for "ITC" in Full Text gives 55 result(s) in Beilstein Journal of Organic Chemistry.
Carbohydrate inhibitors of cholera toxin
Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34
- pocket. Both of these terminal sugar residues show hydrogen bonding interactions with the protein and associated water molecules. The GM1 oligosaccharide (GM1os) binds very tightly to CTB with a dissociation constant (Kd) of around 40 nM (measured by isothermal titration calorimetry, ITC), while simple
- . Individually, the interactions are much weaker than the CTB-GM1os interaction (Kd ca. 1 mM measured by ITC), but even these weak binding interactions can still be functionally useful once the effect of multivalent binding enhancement has been taken into consideration. Indeed, ITC experiments have also shown
Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial
Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5
Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin
Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248
- -(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
- were studied by a set of methods allowing characterization of supramolecular behavior at various levels – from binary complexation, over supramolecular oligomers to large assemblies; namely by isothermal titration calorimetry (ITC) [16], 1H nuclear magnetic resonance spectroscopy (1H NMR), dynamic
- preparation, we observed many sheet-like structures (Figure 6C), corresponding to the observations of Bonini et al [22]. Isothermal titration calorimetry (ITC) ITC experiments on NA-γ-CD cannot be carried out as classical titration experiments, i.e., by injecting the ligand solution into a solution of the
β-Cyclodextrin- and adamantyl-substituted poly(acrylate) self-assembling aqueous networks designed for controlled complexation and release of small molecules
Beilstein J. Org. Chem. 2017, 13, 1879–1892, doi:10.3762/bjoc.13.183
- viscosity of the network as shown by ITC, 1H NMR and UV–vis spectroscopy, and rheological studies. Such networks potentially form a basis for the design of controlled drug release systems. Keywords: controlled release; cyclodextrin; network; poly(acrylate); self-assembly; Introduction The formation of
- designed into the structure of aqueous networks formed between a β-cyclodextrin-substituted poly(acrylate) and three adamantyl-substituted poly(acrylate)s. Accordingly, we report an ITC, 1H NMR and UV–vis spectroscopic and rheological study of three self-assembling networks formed between the 8.8% 6A-(2
- , chosen for this study (Figure 1). Results and Discussion Isothermal titration calorimetry (ITC) studies of substituted poly(acrylate) network formation In aqueous solution, the host β-CDen substituents of PAAβ-CDen complex the guest adamantyl substituents of PAAADen, PAAADhn and PAAADddn to form poly
One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization
Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127
- description see Supporting Information File 1). The eventual content of free RAMEB in the product was checked by isothermal calorimetry (ITC) and was around 3 wt %. The conversion of the monomers was calculated from the yield of polyrotaxane minus the total RAMEB content. In both cases, the monomer
Interactions between shape-persistent macromolecules as probed by AFM
Beilstein J. Org. Chem. 2017, 13, 938–951, doi:10.3762/bjoc.13.95
- connection of one CD moiety at each phenylene unit. Based on the stiffness of the polymer chain self-passivation of CD polymer modified surfaces is reduced to a minimum. Furthermore, the ethynyl end groups are easily functionalized by click chemistry. Isothermal titration calorimetry (ITC), fluorescence
- hydrophilic guest to significantly improve the solubility in water. Binding constants of about 40,000 M−1, which were in the same range as literature values for the incorporation of adamantane derivatives into β-CD, [61] were obtained using ITC measurements considering a two-step sequential complexation with
From steroids to aqueous supramolecular chemistry: an autobiographical career review
Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69
- two until we settled in. Although a much larger department than UNO, UT Austin had a poorer ratio of NMR instruments to students, and so we focused mostly on isothermal titration calorimetry (ITC) based research. There was the small matter of sneaking into a closed city and slipping under the radar of
- the National Guard to “steal” our own hosts, reagents, and ITC instruments; but that story is perhaps for another time. Back in Austin with everything we needed, we got down to some research… and of course filling out countless forms for insurance claims and requests for financial aid from the Federal
Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation
Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7
- isothermal titrimetry calorimetry, ITC [52][70], are frequently used in characterizing host–guest complexation. When viscosity changes occur because of host–guest complexation, rheology may be used to characterize such complexation [71]. Some examples of aqueous polymer systems characterized by these
- octamethylene-linked β-CD dimer c (Figure 10a, b and c) [78] and related β-CD [79][80] dimers in aqueous solution. It was determined from ITC experiments that while β-CD formed a 1:1 host–guest complex with adamantane carboxylate, only one annulus of the β-CD dimer b and β-CD dimer c complexed adamantane
Size-controlled and redox-responsive supramolecular nanoparticles
Beilstein J. Org. Chem. 2015, 11, 2388–2399, doi:10.3762/bjoc.11.260
- sample at least 100 particles were measured. Calorimetric analysis Calorimetric titrations were performed at 25 °C using a Microcal VP-ITC titration microcalorimeter. Sample solutions were prepared in Millipore water. NMR spectroscopy 1H NMR spectra was recorded on a Bruker 400 MHz NMR spectrometer. 1H
- titrations of a) CD-PEI (CD concentration of 0.088 mM, cell) with Ad-TEG (1.1 mM, burette) and b) Ad-TEG (1.1 mM, cell) with CD (10 mM; burette). H = host (CD from CD-PEI or native CD) and G = guest (Ad from Ad-TEG). Experimental binding curve (markers) and best fit to a 1:1 model (line). ITC titration of Fc
The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry
Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134
- inhibitor Gleevec [53][54][55]. Reported by the Innovative Technology Centre (ITC) in 2010, this landmark synthesis was realised as a continuous process featuring an amide formation, a nucleophilic substitution and a Buchwald–Hartwig coupling as key synthesis steps performed in flow (Scheme 4). Further
- . As a consequence this approach is better suited to the rapid formation of small quantities of directly purified material for screening purposes but does not constitute a viable mode of performing direct large scale manufacture. In the same year the ITC also reported on their efforts towards the flow
- incorporated analysis technique. As the safe use of organometallic reagents has emerged as a key facet of flow chemical synthesis [58], the ITC reported on the design and implementation of a dual injection loop system that could deliver solutions of organometallic reagents (i.e., LiHMDS or n-BuLi) as a pseudo
Peptide–polymer ligands for a tandem WW-domain, an adaptive multivalent protein–protein interaction: lessons on the thermodynamic fitness of flexible ligands
Beilstein J. Org. Chem. 2015, 11, 837–847, doi:10.3762/bjoc.11.93
- tandem WW-domain of formin-binding protein (FBP21). Polymer carriers were conjugated with 3–9 copies of the proline-rich decapeptide GPPPRGPPPR-NH2 (P1). Binding of the obtained peptide–polymer conjugates to the tandem WW-domain was investigated employing isothermal titration calorimetry (ITC) to
- multivalent peptide–polymer conjugate to the tandem WW domain Binding studies with peptide–polymer conjugates were conducted employing isothermal titration calorimetry (ITC). This method enables the determination of the binding affinity of the multivalent ligands and elucidates the composition of the free
- multivalency of binding and/or the degree of crosslinking. Thus, the method enables the identification of polymer–protein aggregates containing several polymers and proteins in a complex. No precipitation of the multicomponent aggregates that interfered with ITC measurements was observed during the experiments
Impact of multivalent charge presentation on peptide–nanoparticle aggregation
Beilstein J. Org. Chem. 2015, 11, 792–803, doi:10.3762/bjoc.11.89
- with peptide concentration. Isothermal titration calorimetry (ITC) was used to determine the thermodynamic parameters as well as the binding constant for the assembly of Au/MUA nanoparticles (Table 1). By fitting with a one set of binding site mode the binding stoichiometry N, the binding constant KB
- have almost the same binding stoichiometry determined by ITC. This can be explained by considering the following points. Due to the fibril formation of R2A2, R2A3, and R2A4 Au/MUA nanoparticles interact with distinct positions on the surface of the peptide fiber. Cryo TEM images reveal, that an excess
- ) Cryo TEM images of 100 µM R2A2 and 0.4 µM Au/MUA nanoparticles at pH 9 at a defocus of −1.8 µM. Thermodynamic parameters for the aggregation of Au/MUA nanoparticles with peptides VW05, R2A2, R2A3, and R2A4 obtained by ITC. List of amino acid to arginine ratios for the sequences investigated here
Discrete multiporphyrin pseudorotaxane assemblies from di- and tetravalent porphyrin building blocks
Beilstein J. Org. Chem. 2015, 11, 748–762, doi:10.3762/bjoc.11.85
- dealing with the daunting task to quantify the binding constants for the di- and tetravalent multiporphyrin complexes for example using isothermal calorimetry (ITC), in order to analyze the thermodynamics and kinetics of multivalent binding in these architectures in detail. In the future, we will continue
Exploring monovalent and multivalent peptides for the inhibition of FBP21-tWW
Beilstein J. Org. Chem. 2015, 11, 701–706, doi:10.3762/bjoc.11.80
- the interaction between hPG-peptide conjugate 2 and FBP21-tWW was measured by isothermal titration calorimetry (ITC) and compared to the KD of the interaction between the monovalent peptide and FBP21-tWW to analyze if multivalent display in form of the hPG-peptide conjugate 2 increases binding
- aromatic residue N-terminal to the polyproline stretch could also be observed. To define an optimized single monovalent binder, we analyzed the affinities for a selected set of ligands from this panel of sequences with regard to FBP21’s WW domains by ITC under the same conditions as were used for the phage
- highest frequency in the phage display experiment (RPPCGYPLP), did not show any binding to either WW domain in ITC experiments, possibly reflecting the potential of the cysteine residue to form an unspecific complex with glutathione-S-transferase. Similarly, the peptide RPPPPHFPQ could not be confirmed as
Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface
Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20
- PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid
- guest molecules (salicylic acid – SAL, p-methoxyphenol – MEQ, p-nitroaniline – NIA) at three different pH values (2.50, 7.00, 10.00) (Scheme 2). The Ks values were obtained by isothermal titration microcalorimetry (ITC) [32][33], which was selected as the most suitable method for our purpose. Other
- methods were also tested, but their usability was found to be lower than ITC. For example 1H NMR spectroscopy [34] requires relatively high concentrations of the guest and host molecules, which are often impossible to achieve due to the poor solubility in aqueous media. Conventional UV–vis spectroscopy
Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers
Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14
- -cyclodextrin polymers. In aqueous solution nanoparticles were formed from association between the (S)-camptothecin–dextran polymers and the β-cyclodextrin polymers. Keywords: (S)-camptothecin; cyclodextrins; fluorescence; nanoparticles; ITC; Introduction Cancer remains to be the major cause of mortality in
- ). Binding properties and formation of nanoparticles The ability to form inclusion complexes with β-CD and β-CD-polymers was determined by isothermal titration calorimetry (ITC) and fluorescence spectroscopy. The β-CD polymer (D70HPβ-CD) had been prepared from a 70 kDa dextran backbone modified with 6
- formation is enthalpy driven in the case of D10GP-CPT1, but mainly entropy driven (|TΔS| > |ΔH|) in the case of D70GP-CPT2. This high positive entropy variation shows a cooperative inclusion of the polymers. No binding between native β-CD and D70GP-CPT2 could be measured by ITC. Figure 1 shows the heat flow
Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer
Beilstein J. Org. Chem. 2014, 10, 2874–2885, doi:10.3762/bjoc.10.304
- . The photoinduced, switchable binding behavior of AZO-CDim 1 was evaluated by ITC, NMR and molecular modeling in the presence of a ditopic adamantyl guest. The results indicate that AZO-CDim 1 can form two different inclusion complexes with an adamantyl dimer depending on its photoinduced isomers. Both
- binding site of the ditopic guest ADAdim 4 and one binding site of a particular β-CD dimer, bearing a terephthalic acid linker, was independent of the number of binding sites, that is, no cooperative effect was observed and a supramolecular polymer was formed. ITC is one of the most interesting methods to
- , enthalpies of dilution of the monotopic hosts β-CD and β-CD-NH2, the ditopic host AZO-CDim 1 and the guest ADAdim 4 were measured in separate experiments to determine the maximum concentration to use for the ITC experiments. Enthalpies of dilution of β-CD and β-CD-NH2 were negligible over a broad
Improving ITC studies of cyclodextrin inclusion compounds by global analysis of conventional and non-conventional experiments
Beilstein J. Org. Chem. 2014, 10, 2630–2641, doi:10.3762/bjoc.10.275
- techniques ranging from spectroscopy to chromatography and including calorimetrical tools [1][2][3][4]. Within this scope, isothermal titration calorimetry (ITC) is gaining more and more importance, as it allows a complete thermodynamic description of the inclusion phenomena (binding constant K, inclusion
- enthalpy ΔH, inclusion entropy ΔS, heat capacity variation ΔCp ) [5][6][7][8][9][10][11]. On a methodological point of view, most ITC studies are based on the classical titration protocol. While one partner of the studied phenomenon, called titrand, is placed inside the cell, the second partner, called
- titrant, is contained in the syringe of the ITC device. Each injection of one partner on the other induces the formation of supramolecules, thus releasing an amount of heat which is proportional to the binding enthalpy and to the amount of complexes formed during this addition. The binding isotherm is
Towards the sequence-specific multivalent molecular recognition of cyclodextrin oligomers
Beilstein J. Org. Chem. 2014, 10, 2428–2440, doi:10.3762/bjoc.10.253
- complementary and non-complementary strands modified with guest molecules and the investigation of their complexation behavior towards each other by isothermal titration calorimetry (ITC). As complementary binding motifs n-butyl and α-CD and adamantane and β-CD were selected. It was found that it is possible to
- towards α- and β-CD was investigated by ITC experiments. The structures of the host–guest complexes were elucidated by NMR spectroscopy. The 1-adamantane-functionalized serine 17 shows complexation of α- and β-CD, forming 1:1 complexes. In both cases the adamantane moiety binds into the CD cavity, which
- 10 equivalents of α-CD (Figure 6B and C). The interaction of 18 with β-CD cannot be quantified based on the ITC measurement with 1 mM of 18 and 10 mM of β-CD. Nevertheless, the NMR spectra of the 1:10 mixture of 18 and β-CD show small variations in the chemical shifts of the protons compared to the
Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation
Beilstein J. Org. Chem. 2014, 10, 1981–1990, doi:10.3762/bjoc.10.206
- . Both homo- and heterobifunctional ligands are obtained by a straightforward preparative route, as an innovative approach. Additionally, isothermal titration calorimetry (ITC) and dynamic light scattering (DLS) helped to better understand lectin–ligand interactions between lecA or lecB and these
- lecB were determined by isothermal titration calorimetry (ITC) by addition of the ligands to a solution of lectin (Figure 3). Dissociation constants (Kd) and thermodynamic parameters (ΔG, ΔH, −TΔS) are listed in Table 1, together with the experimental binding stoichiometry (n), defined as the number of
- cluster 17 containing two D-galactose and one D-glucose residues provided better ITC titration curves and more rational n values than the bis D-galactosyl monopropargyl cluster 16, which may reflect precipitation of the lectin-cluster complex during the ITC experiment in the latter case, based on the DLS
Synthesis and solvodynamic diameter measurements of closely related mannodendrimers for the study of multivalent carbohydrate–protein interactions
Beilstein J. Org. Chem. 2014, 10, 1524–1535, doi:10.3762/bjoc.10.157
- experimental conditions that often biased the intrinsic phenomena under investigations [29]. For instance, when evaluating thermodynamic parameters by isothermal calorimetry (ITC), scientists used either truncated versions of for instance, tetrameric lectins such as ConA, or diluted conditions to avoid
Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin
Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138
- the parallel HisHis compared to the antiparallel HisHis [40]. Isothermal titration calorimetry (ITC) confirmed that the interaction of FITC-HisHis (mixture of isomers) and NANA is characterized by the same stoichiometry (1:2) and nearly the same binding constants (K1 = 163 M−1 and K2 = 5.36 × 103 M−1
- ) were obtained. ITC data are provided in Supporting Information File 1. These findings indicate that the introduction of the FITC label does not affect the formation of the synthetic lectin HisHis and its interaction with NANA. Since the mixture of isomers is much more easily synthesized than the
Camera-enabled techniques for organic synthesis
Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118
- efficient use of space and the opportunity for a 24/7 working regime, the ability of digital cameras to provide real-time information on the state of a laboratory is particularly useful. When we established our Innovative Technology Centre (ITC) for advanced chemical synthesis in 2005, all of the fume-hoods
Influence of cyclodextrin on the solubility and the polymerization of (meth)acrylated Triton® X-100
Beilstein J. Org. Chem. 2012, 8, 2176–2183, doi:10.3762/bjoc.8.245
- -complex was monitored by viscosity measurements. Results and Discussion Complexation study of Triton® X-100 with RAMEB-CD The complexation behavior of Triton® X-100 (1) with RAMEB-CD was investigated by means of an ITC experiment (Supporting Information File 1, Figure S1). Assuming the sequential-binding
- experiments were performed on a VP-ITC MicroCalorimeter from MicroCal, Northampton MA, and were controlled by MicroCal VP viewer 2000 ITC software. Experiments were conducted at 25 °C. A 2.5 mM solution of RAMEB-CD was titrated against a 0.2 mM solution of Triton® X-100. Titration was carried out by 30
- injections of 5 × 1 μL, 5 × 2 μL, 5 × 5 μL, 15 × 15 μL with a spacing time of 180 s. The stirring speed was set to 300 min−1. In a separate experiment the heat of dilution was measured and was subtracted from the binding isotherm. The results were calculated with Origin 7.0 and the MicroCal LLC ITC software
Influence of intramolecular hydrogen bonds on the binding potential of methylated β-cyclodextrin derivatives
Beilstein J. Org. Chem. 2012, 8, 1890–1895, doi:10.3762/bjoc.8.218
- regioselective methods. Binding free energies and binding enthalpies of these hosts towards 4-tert-butylbenzoate and adamantane-1-carboxylate were determined by isothermal titration microcalorimetry (ITC). It was found that methyl substituents at the secondary positions of β-CD lead to a tremendous reduction of
- these guests should sensitively respond to changes in the methylation pattern, because they fit tightly into the cavity of β-CD giving rise to high binding constants [26][27]. Binding data were measured by isothermal titration calorimetry (ITC) because it is known to be the most accurate method, and
- because it additionally yields binding enthalpies and entropies [31][32]. Results Since methylated β-CD derivatives 2–6 are highly water-soluble they are well suited for ITC. The ITC titration curves for all the β-CD derivatives 1–6 were exothermic and were in accordance with a 1:1 stoichiometry of the
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