18 research outputs found

    Relative inhibitory effects of selected known and newly tested compounds against ADC.<sup>[a]</sup>

    No full text
    [a]<p>The measurements were performed using 1 mM L-aspartate, 3 µM ADC, and 1 mM compound (potential inhibitor) in D<sub>2</sub>O at 25°C.</p>[b]<p>The conversion percentage corresponds to the product formed by integration of the <sup>1</sup>H NMR signals corresponding to substrate and product of the enzymatic reaction after ca. 30 min upon addition of the enzyme. The time was adjusted to correspond to 50% conversion in the <i>absence</i> of inhibitor (reference). The absolute values were averaged from at least two independent assays.</p>[c]<p>The relative inhibitory effect, <i>k</i><sub>rel</sub>, was calculated as the ratio of the conversion percentages in the presence and absence of compound.</p>[d]<p>While full inhibition was also observed when using double the enzyme concentration, i.e., 6 µM, only a small nhibitory effect could be detected (<i>k</i><sub>rel</sub> = 0.9) when the assay was performed with 100 µM oxaloacetate, i.e., at a 10-fold lower inhibitor concentration.</p>[e]<p>A smaller <i>k</i><sub>rel</sub> value of 0.74, suggesting moderate inhibition, was observed upon preincubation with ADC for 1 h at ambient temperature.</p

    Dodecaborate-Functionalized Anchor Dyes for Cyclodextrin-Based Indicator Displacement Applications

    No full text
    A new type of water-soluble anchor dyes, that is, dyes which carry an auxiliary unit for strong binding to macrocyclic host molecules, has been synthesized. It consists of 7-nitrobenzofurazan (NBD) as a dye and the dodecaborate cluster (B<sub>12</sub>H<sub>11</sub>R) as a dianionic, globular, and purely inorganic anchoring group for cyclodextrins (<i>K</i><sub>a</sub> > 10<sup>5</sup> M<sup>–1</sup>). The synthesized dodecaborate-substituted dyes show marked changes in their photophysical properties (UV–vis and fluorescence) upon complexation with cyclodextrins (β-CD and γ-CD), such that the resulting host·dye complexes (1:1 stoichiometry) present sensitive reporter pairs for indicator displacement applications

    Nanomolar Binding of Steroids to Cucurbit[<i>n</i>]urils: Selectivity and Applications

    No full text
    Cucurbit­[<i>n</i>]­urils (CB<i>n</i>, <i>n</i> = 7, 8) serve as artificial receptors for steroids (21 tested), including the hormones testosterone and estradiol as well as steroidal drugs. Fluorescence displacement titrations and isothermal titration calorimetry (ITC) provided up to nanomolar binding affinities in aqueous solution for these hydrophobic target molecules, exceeding the values of known synthetic receptors. Remarkable binding selectivities, even for homologous steroid pairs, were investigated in detail by NMR, X-ray crystal diffraction, ITC, and quantum chemical calculations. Notably, the CB<i>n</i>•steroid complexes are stable in water and buffers, in artificial gastric acid, and even in blood serum. Numerous applications have been demonstrated, which range from the solubility enhancement of the steroids in the presence of the macrocycles (up to 100 times, for drug delivery) and the principal component analysis of the fluorescence responses of different CB<i>n</i>•reporter dye combinations (for differential sensing of steroids) to the real-time monitoring of chemical conversions of steroids as substrates (for enzyme assays)

    Nanomolar Binding of Steroids to Cucurbit[<i>n</i>]urils: Selectivity and Applications

    No full text
    Cucurbit­[<i>n</i>]­urils (CB<i>n</i>, <i>n</i> = 7, 8) serve as artificial receptors for steroids (21 tested), including the hormones testosterone and estradiol as well as steroidal drugs. Fluorescence displacement titrations and isothermal titration calorimetry (ITC) provided up to nanomolar binding affinities in aqueous solution for these hydrophobic target molecules, exceeding the values of known synthetic receptors. Remarkable binding selectivities, even for homologous steroid pairs, were investigated in detail by NMR, X-ray crystal diffraction, ITC, and quantum chemical calculations. Notably, the CB<i>n</i>•steroid complexes are stable in water and buffers, in artificial gastric acid, and even in blood serum. Numerous applications have been demonstrated, which range from the solubility enhancement of the steroids in the presence of the macrocycles (up to 100 times, for drug delivery) and the principal component analysis of the fluorescence responses of different CB<i>n</i>•reporter dye combinations (for differential sensing of steroids) to the real-time monitoring of chemical conversions of steroids as substrates (for enzyme assays)

    Analysis of PorACj secondary structure.

    No full text
    <p>(A) The panel shows the hydrophobicity indices of the individual amino acids of PorACj according to ref <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0075651#pone.0075651-Kyte1" target="_blank">[80]</a>. (B) The secondary structure of PorACj was predicted using a consensus method [83] at the Pole Bioinformatique Lyonnaise network (<a href="http://npsa-pbil.ibcp.fr/cgi-bin/npsa_automat.pl?page=/NPSA/npsa_seccons.html" target="_blank">http://npsa-pbil.ibcp.fr/cgi-bin/npsa_automat.pl?page=/NPSA/npsa_seccons.html</a>); the protein was suggested to form α-helices. Amino acid residues arranged on basis of heptameric repeats (a–g) showing distinct separation in a hydrophobic domain supposable surrounded by lipid molecules (dark grey) while the hydrophilic domain (light grey) is suggested to represent the component orientated to the water-filled lumen in the presumed oligomeric PorACj.</p

    Investigation of the voltage-dependence of PorACj in single-channel experiments.

    No full text
    <p>A: The purified protein was added to the <i>cis</i>-side of a PC membrane (10 ng/ml) and the reconstitution of channels was followed until about 10 PorACj-channels inserted into the membrane. Then 40 mV were applied to the <i>cis</i>-side of the membrane, and the membrane current was measured as a function of time. The aqueous phase contained 1M KCl; T = 20°C. B: Histogram of 56 closing events of the experiment in A and and similar experiments. The closing events were plotted in a bargraph as a function of the conductance of the closing events. ! M KCl; T = 20°C. Note that the PorACj channels closed in two distinct conductance values of 1 and 2 nS.</p
    corecore