Search

The investigation of molecular mechanisms that regulate the polymerization of tau associated with increased neurodegeneration in Alzheimer's disease and other related tauopathies indicate that the molar ratio of inducer to protein is a greater determinant of the rate and extent of tau polymerization than the concentration of tau itself.

The pseudohyperphosphorylation mutants consisting of six and seven sites in the proline-rich region and carboxy terminus of tau by amino acid substitution were generated to address to understand the functional consequences of hyperphosphorylation on the microtubule binding and polymerization of tau. The decreased affinity of pseudohyperphosphorylated tau observed for microtubules and reduced inducer-initiated rates of nucleation and polymerization might be responsible for the increased cytotoxicity of hyperphosphorylated tau in AlzheimerEs disease and also explained the potentially beneficial role of tau polymerization and NFT formation.

The effect of monovalent ions on both the reactivity and global folding of the 8-17 DNAzyme is examined and the results are compared with those of the hammerhead ribozyme that has similar size and secondary structure. The results have shown that [Pb.sup.2+]-dependent function has followed a different mechanism from the monovalent metal ions and other divalent metal ions and the metal-ion dependent folding and structural changes have played a vital role in the catalytic function of the 8-17 DNAzyme.

Colloidosomes have attracted great interest in recent years because of their capability for storage and delivery of small molecules for medical and pharmaceutical applications. However, traditional polymer shell colloidosomes leak low molecular weight drugs due to their intrinsic shell permeability. Here, we report aqueous core colloidosomes with a silver shell, which seals the core and makes the shell impermeable. The silver-coated colloidosomes were prepared by reacting l-ascorbic acid in the microcapsule core with silver nitrate in the wash solution. The silver shell colloidosomes were then modified by using 4,4'-dithiodibutyric acid and cross-linked with rabbit Immunoglobulin G (IgG). Label-free surface plasmon resonance was used to test the specific targeting of the functional silver shell with rabbit antigen. To break the shells, ultrasound treatment was used. The results demonstrate that a new type of functional silver-coated colloidosome with immunoassay targeting, nonpermeability, and ultrasound sensitivity could be applied to many medical applications. [ABSTRACT FROM AUTHOR]

Sulfhydryl-containing proteins play critical roles in various physiological and biological processes, and the activities of those proteins have been reported to be susceptible to thiol oxidation. Therefore, the development of protein thiol target fluorescent probe is highly desirable. In the present work, a biotinylated coumarin fluorescence "off-on" probe SQ for selectively detecting protein thiols in biotin receptor-positive cancer cells was designed with a 2,4-dinitrobenzenesulfony as the thiol receptor. The probe exhibited dramatic fluorescence responses toward sulfhydryl-containing proteins (ovalbumin (OVA), bovine serum albumin (BSA)): up to 170-fold fluorescence enhancement with 70 nm blue-shift was observed with the addition of OVA. However, low molecular weight thiols (Cys, glutathione (GSH), Hey) caused negligible fluorescence changes of SQ In addition, biotin receptor-positive Hela cells displayed strong red and green fluorescence after incubation of SQfor 1 h; neither red nor green fluorescence signal could be visualized in biotin-negative normal lung Wi38 cells. These results imply that the probe has potential application in fluorescent imaging protein thiols on the surface of Hela cells. [ABSTRACT FROM AUTHOR]

Combustionheats of FOX-7 and its five closed-loop derivativeswere determined and the standard molar enthalpies of formation (ΔfH°m) were obtained. The sequenceof combustion heat for the six compounds is DNDH > MDNZ > DNDX> DNDZ> DDNI > FOX-7. Combustion heat tends to rise with the increaseofthe number of C atoms in the molecule. Specific heat capacities weremeasured, and the standard molar heat capacities of the six compoundsare (176.59, 205.41, 207.76, 218.89, 217.76, and 215.40) J·mol–1·K–1, respectively. The specificheat capacity presents an opposite change rule with combustion heat.To the isomers and the introduction of hydroxyl group, the changerule is the same. Moreover, the introduction of hydroxyl group canmarkedly decrease the combustion heat and specific heat capacity. [ABSTRACT FROM AUTHOR]

Transformation of bisphenol A (BPA) by ammonia-oxidizing bacteria (AOB) Nitrosomonas europaea ATCC 19718 was investigated. On the basis of the ultraperformance liquid chromatography (UPLC) coupled to quadrupole time-of-flight mass spectrometry (Q-TOF MS) and nuclear magnetic resonance analysis, we found N. europaea could transform BPA into nitro- and dinitro-BPA, suggesting that abiotic nitration between the biogenic nitrite and BPA played a major role in the transformation of BPA in the batch AOB system. Nitrite concentrations, temperature, and pH values were the major factors to influence the reaction rate. Furthermore, the yeast estrogenic screening assay showed that the formed nitro- and dinitro-BPA had much less estrogenic activity as compared with its parent compound BPA. Similar reactions of abiotic nitration were considered for 4-n-nonylphenol (nNP) and 4-n-octylphenol (nOP) since nitro-nNP and nitro-nOP were detected by UPLC-Q-TOF MS. In addition, results from the local wastewater treatment plant (WWTP) showed the occurrence of nitro-BPA and dinitro-BPA during the biological treatment process and in the effluent, indicating that nitration of BPA is also a pathway for removal of BPA. Results of this study provided implication that AOB in the WWTPs might contribute to removal of selected endocrine-disrupting compounds (EDCs) through abiotic nitritation. [ABSTRACT FROM AUTHOR]

Three isomorphous metal-organic frameworks of formula [M(ppdc)(H2O)2]n [M = Mn(II), Fe(II), and Co(II)] were synthesized from sodium p-phenylenediacrylic (Na2ppdc). Crystallographic studies revealed that the compounds are layer-pillared 3D frameworks in which the square-grid M(II) layers with single carboxylate bridges are interlinked by long organic spacers with large interlayer separations of about 13 Å. Magnetic investigations indicated that they all display intralayer antiferromagnetic interactions through the carboxylate bridges in the unusual skew-skew coordination mode but the bulk behaviors are quite different. The Co(II) compound, like most compounds containing similar M-O-C-O-M layers, shows no 3D magnetic ordering down to 2 K, while the Mn(II) and Fe(II) compounds exhibit spin-canted ordering, behaving as a weak ferromagnet (TC = 3.8 K) and a metamagnet (TN = 3.8 K, Hc = 650 Oe), respectively. Spin-canted ordering is still a rarity in this series of materials. Magnetostructural comparisons with analogous compounds indicate that the occurrence of spin-canted ordering can be related to the uncommon skew-skew and anti-anti coordination modes of carboxylate bridges, which induce stronger antiferromagnetic interactions than the common syn-anti mode. [ABSTRACT FROM AUTHOR]

A 2-fold interpenetrated metal−organic framework displaying intense yellow fluorescence is constructed from [Zn4O(COO)6] clusters and a new dicarboxylate ligand bearing the fluorene chromophore fluorene-2,7-dicarboxylic acid. The [Zn4O(COO)6] secondary building unit exhibits unusual coordination features and leads to the rare 3D pillared kagomé net topology (324865). [ABSTRACT FROM AUTHOR]

Focuses on the use of enhanced-fluidity liquid chromatography for chiral separations. Comparison of the technique to high performance liquid chromatography and supercritical fluid chromatography; Applicability of fluoroform as fluidity-enhancing solvent for chiral separations.