betadex and 1-anilino-8-naphthalenesulfonate

Nanoparticles comprising copolymers of aminoethylcarbamoyl-beta-cyclodextrin (AEC-beta-CD) and ethylene glycol diglycidyl ether (EGDGE) are prepared by an interfacial polyaddition reaction in a miniemulsion system. Polymers are formed in a W/O emulsion containing 0.25-10.0% (w/w) water and 5.0% (w/w) surfactant (MO-3S, tetraglycerin monoester, HLB 8.8), where simple particles are predominantly obtained when the water content is 1.0% and 5.0%. Notably, nano-size small particles (diameter: 0.3 microm) are formed under the condition of 5.0% water and 5.0% surfactant, which have the highest beta-CD contents (75.5 wt.%) and the most positive zeta-potential (53.6 mV). The zeta-potential measurement indicates that the obtained particles have positive charge due to protonation of their amino groups below around pH 10. Actually, uptake of 8-anilino-1-naphthalenesulfonic acid (ANS) bearing negative charge (SO(3)(-)) and moderate hydrophobicity depends on the magnitude of zeta-potential of the particles; viz., the particles with zeta-potential of 53.6 mV show the highest efficiency of uptake. The diameter and the beta-CD contents are closely related with the water/surfactant ratio, and the zeta-potentials are dependent on both the diameter and the beta-CD contents. Inclusion of ANS into the CD cavity of EGDGE/AEC-beta-CD particles can be controlled by electrostatic interaction between ANS (negatively charged) and the particle (positively charged). Namely, synergistic effect of cavity-inclusion and electrostatic interaction can dominate the uptake of guest molecules by the particles.

Topics: Anilino Naphthalenesulfonates; beta-Cyclodextrins; Drug Carriers; Emulsions; Epoxy Resins; Fluorescent Dyes; Hydrogen-Ion Concentration; Nanostructures; Nanotechnology; Polymers; Surface-Active Agents; Technology, Pharmaceutical; Water

Three beta-cyclodextrin (beta-CyD) derivatives with crown ether units, that is N-(4'-benzo-15-crown-5)-6-imino-6-deoxy-beta-CyD (2), 6,6'-[N-(4,4'-dibenzo-18-crown-6)-imino]-bridged bis(beta-CyD)(3), and 2,2'-[O-(4',5'-benzo-15-crown-5)-ethyl]-bridged bis (beta-CyD)(5), were synthesized as cooperative recognition receptor models. Their molecular binding behavior with four representative fluorescent dyes, i.e., ammonium 8-anilino-1-naphthalenesulfonate (ANS), sodium-6-toluidino-2-naphthalene-sulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB), was investigated in buffer solutions (pH = 7.20) at 25 degreesC by means of circular dichroism, NMR and fluorescence spectroscopy. 2D-ROESY experiments showed that dyad host 2 and triad host 3 adopted a CyD-guest-crown ether binding mode, while triad host 5 adopted a CyD-guest-CyD binding mode, upon inclusion complexation with guest molecules. Therefore, hosts 2 and 3 showed high molecular recognition ability towards charged guests, giving an enhanced binding ability up to 115 times for ANS by 3 and fairly high molecular selectivity up to 1450 times for the ANS/AR pair by 2 as compared with native beta-CyD in an aqueous phosphate buffer solution. On the other hand, host 5 was found to be able to effectively recognize the shape of a guest molecule, showing significantly higher binding ability towards linear guests. The binding affinities and molecular recognition abilities of these CyD-crown ether conjugates towards guest molecules are discussed from the viewpoint of electrostatic and/or hydrophobic interactions, size/shape-fit concept, and multiple recognition mechanism between host and guest.

Topics: Anilino Naphthalenesulfonates; beta-Cyclodextrins; Binding Sites; Circular Dichroism; Crown Ethers; Cyclodextrins; Fluorescent Dyes; Hydrophobic and Hydrophilic Interactions; Ligands; Magnetic Resonance Spectroscopy; Models, Chemical; Models, Molecular; Molecular Structure; Naphthalenesulfonates; Rhodamines; Spectrometry, Fluorescence; Static Electricity

In order to evaluate the ability of multivalent glycosides based on a beta-cyclodextrin core as site-specific molecular carriers, a study on both the inclusion complexation behaviour and lectin binding affinity of branched and hyperbranched beta-cyclodextrins is presented. A series of cluster galactosides constructed on beta-cyclodextrin scaffolds containing seven 1-thio-beta-lactose or beta-lactosylamine bound to the macrocyclic core through different spacer arms were synthesised. In addition, the first synthesis of three first-order dendrimers based on a beta-cyclodextrin core containing fourteen 1-thio-beta-D-galactose, 1-thio-beta-lactose and 1-thio-beta-melibiose residues was performed. Calorimetric titrations performed at 25 degrees C in buffered aqueous solution (pH 7.4) gave the affinity constants and the thermodynamic parameters for the complex formation of these beta-cyclodextrin derivatives with guests sodium 8-anilino-1-naphthalenesulfonate (ANS) and 2-naphthalenesulfonate, and lectin from peanut (Arachis hypogaea) (PNA). The persubstitution of the primary face of the beta-cyclodextrin with saccharides led to a slight increase of the binding constant values for the inclusion complexation with ANS relative to the native beta-cyclodextrin. However, the increase of the steric congestion due to the presence of the saccharide residues on the narrow rim of the beta-cyclodextrin may cause a decrease of the binding ability as shown for sodium 2-naphthalenesulfonate. The spacer arms are not passive elements and influence the host binding ability according to their chemical nature. PNA forms soluble cross-linked complexes with cluster galactosides and lactosides scaffolded on beta-cyclodextrin but not with cluster galactopyranosylamines or melibiose. Both, perbranched and hyperbranched beta-cyclodextrins, form stronger complexes with PNA than the monomeric analogues. However, the use of hyperbranched CDs does not contribute to the improvement of the complex stability relative to heptakis-glycocyclodextrin derivatives. Finally, a titration experiment with PNA and a complex formed by a heptakis lactose beta-cyclodextrin derivative with sodium 2-naphthalenesulfonate showed the formation of a soluble cross-linked complex with stronger affinity constant and higher stoichiometry than those observed for the complex formation of PNA with the same heptakis-lactose beta-cyclodextrin derivative, suggesting the formation of a three component complex.

Topics: Anilino Naphthalenesulfonates; Arachis; beta-Cyclodextrins; Binding Sites; Calorimetry; Cyclodextrins; Drug Delivery Systems; Galactosides; Lectins; Naphthalenesulfonates; Structure-Activity Relationship; Substrate Specificity; Thermodynamics; Titrimetry

GroEL has a greater affinity for the mitochondrial isozyme (mAAT) of aspartate aminotransferase than for its cytosolic counterpart (cAAT) (Mattingly JR Jr, Iriarte A, Martinez-Carrion M, 1995, J Biol Chem 270:1138-1148), two proteins that share a high degree of sequence similarity and an almost identical spatial structure. The effect of detergents on the refolding of these large, dimeric isozymes parallels this difference in behavior. The presence of non-ionic detergents such as Triton X-100 or lubrol at concentrations above their critical micelle concentration (CMC) interferes with reactivation of mAAT unfolded in guanidinium chloride but increases the yield of cAAT refolding at low temperatures. The inhibitory effect of detergents on the reactivation of mAAT decreases progressively as the addition of detergents is delayed after starting the refolding reaction. The rate of disappearance of the species with affinity for binding detergents coincides with the slowest of the two rate-limiting steps detected in the refolding pathway of mAAT. Limited proteolysis studies indicate that the overall structure of the detergent-bound mAAT resembles that of the protein in a complex with GroEL. The mAAT folding intermediates trapped in the presence of detergents can resume reactivation either upon dilution of the detergent below its CMC or by adding beta-cyclodextrin. Thus, isolation of otherwise transient productive folding intermediates for further characterization is possible through the use of detergents.

Topics: Anilino Naphthalenesulfonates; Animals; Aspartate Aminotransferases; beta-Cyclodextrins; Chaperonin 60; Cyclodextrins; Cytosol; Detergents; Dose-Response Relationship, Drug; Fluorescent Dyes; Guanidine; Hydrogen-Ion Concentration; Isoenzymes; Kinetics; Liver; Micelles; Mitochondria; Molecular Chaperones; Octoxynol; Polyethylene Glycols; Protein Folding; Rats; Spectrometry, Fluorescence; Temperature; Time Factors; Trypsin

The interaction of 8-anilinonaphthalene-1-sulfonate with beta-cyclodextrin was investigated in 0.1 M phosphate buffer at pH 7.4 by fluorescence spectrophotometry. Utilizing the fact that the fluorescence intensity of 8-anilinonaphthalene-1-sulfonate increases in the presence of beta-cyclodextrin, the thermodynamic parameters for the inclusion complex formation were determined as follows: delta G degrees = -2.52 kcal/mol at 25 degrees C, delta H degree = -1.92 kcal/mol, and delta S degree = 2.1 eu. The driving forces for the inclusion complex formation were considered to be van der Waals-London dispersion force and hydrophobic interaction. Also, from the measurements of 1H NMR spectra and from studying the Corey-Pauling-Koltun (CPK) model, the structure of the inclusion complex was discussed.

Topics: Anilino Naphthalenesulfonates; beta-Cyclodextrins; Circular Dichroism; Cyclodextrins; Fluorescent Dyes; Magnetic Resonance Spectroscopy; Protons; Spectrometry, Fluorescence; Spectrophotometry; Thermodynamics