Thin chip microsprayer system coupled to quadrupole time-of-flight mass spectrometer for glycoconjugate analysis

A thin chip polymer-based microsprayer has been coupled to a hybrid quadrupole time-of-flight mass spectrometer (QTOF MS) and introduced in carbohydrate research. The feasibility of the approach is demonstrated for mapping, sequencing and structural elucidation of glycoconjugates originating from human body fluids and tissues such as a glycopeptide mixture from normal human urine and an isolated and purified GT1 ganglioside fraction from normal adult human brain. The optimization procedure required by each glycoconjugate category is described and the advantages of the system in terms of flexibility and adaptability to QTOF MS, stability of the ESI MS signal, carbohydrate ionization and sequencing, sensitivity, speed of analysis and sample consumption are discussed.     

Syntheses of reactive fluorescent stains derived from 5(2)-aryl-2(5)-(4-pyridyl)oxazoles and bifunctionally reactive linkers

Several bifunctionally reactive linkers containing halide or sulfonate ester groups were prepared. The linkers were used to quaternize 5-(4-methoxyphenyl)-2-(4-pyridyl)oxazole and 2-(6-chromanyl)-5-(4-pyridyl)oxazole to produce fluorescent stains that contained a reactive group such as an isothiocyanate, an N-hydroxysuccinimidyl ester, a maleimide, or an oxirane. The stains were derivatized with either 1-propylamine, 1-propanethiol, or piperidine, as appropriate, to help in characterization. The stains may serve as more photostable alternatives to fluoresceins or coumarins.     

The existence of non-topological solitons in the self-dual Chern-Simons theory

In the recently discovered (2+1)-dimensional relativistic Chern-Simons model, self-duality can be achieved when the Higgs potential density assumes a special form for which both the asymmetric and symmetric vacua are ground state solutions. This important feature may imply the coexistence of static topological and non-topological vortex-like solutions inR ² but the latter have been rather elusive to a rigorous construction. Our main purpose in this paper is to prove the existence of non-topological radially symmetricN-vortex solutions in the self-dual Chern-Simons model. By a shooting method, we obtain a continuous family of gauge-distinctN-vortex solutions. Moreover, we are also able to classify all possible bare (or 0-vortex) solutions.     

Bioactive steroidal glycosides from the marine sponge Erylus lendenfeldi

Bioassay-guided fractionation of the methanol extract of Erylus lendenfeldi using engineered strains of budding yeast (Saccharomyces cerevisiae) has resulted in the isolation of the known compound eryloside A (1) and two new compounds, erylosides K (2) and L (3). The structures were established based mainly on 1D and 2D NMR data. The absolute stereochemistry of eryloside A, which had never been fully characterized, was determined using the modified Mosher's method. The absolute stereochemistry of eryloside K was determined by comparison with tetrahydroeryloside A. Compounds 1-3 exhibited selective cytotoxicity against a yeast strain (Δrad50) deficient in double strand break (DSB) repair.     

A new strategy for the construction of the imidazo[1,5-a]quinoxalin-4-one ring system and its application to the efficient synthesis of BMS-238497, a novel and potent Lck inhibitor

A new efficient strategy was developed for the construction of the imidazo[1,5-a]quinoxalin-4-one ring system. The new method involves condensation of o-nitroaniline with glyoxylate in methanol followed by treatment of the resulting alpha-(o-nitroanilino)-alpha-methoxy acetate with tosylmethyl isocyanide (TosMIC) reagent to give 1-(o-nitrophenyl)imidazole-5-carboxylate. Reductive cyclization of the nitro imidazole carboxylate afforded imidazo[1,5-a]quinoxalin-4-one in three steps and 60% overall yield. The new method was successfully applied to the synthesis of BMS-238497, a novel and potent Lck inhibitor.     

Aerobic catalytic photooxidation of olefins by an electron-deficient Pacman bisiron(III) mu-oxo porphyrin

The synthesis and oxygen atom transfer (OAT) photoreactivity of a diiron(III) mu-oxo meso-tripentafluorophenyl bisporphyrin appended to a dibenzofuran spacer are presented. Reaction of 4,6-diformyldibenzofuran under standard Lindsey conditions furnishes the parent cofacial porphyrin architecture in a single step. These cofacial porphyrins photocatalyze the oxidation of sulfides and olefins using visible light and molecular oxygen as the terminal oxidant. High turnover numbers reflect the enhanced stability of the electron-deficient diiron(III) mu-oxo bisporphyrin core appended to a dibenzofuran spacer under aerobic conditions.     

Hydrogen storage in the dehydrated prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn)

The porosity and hydrogen storage properties for the dehydrated Prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn) are reported. Argon sorption isotherms measured at 87 K afford BET surface areas ranging from 560 m2/g for Ni3[Co(CN)6]2 to 870 m2/g for Mn3[Co(CN)6]2; the latter value is comparable to the highest surface area reported for any known zeolite. All six compounds show significant hydrogen sorption at 77 K and 890 Torr, varying from 1.4 wt % and 0.018 kg H2/L for Zn3[Co(CN)6]2 to 1.8 wt % and 0.025 kg H2/L for Cu3[Co(CN)6]2. Fits to the sorption data employing the Langmuir-Freundlich equation give maximum uptake quantities, resulting in a predicted storage capacity of 2.1 wt % and 0.029 kg H2/L for Cu3[Co(CN)6]2 at saturation. Enthalpies of adsorption for the frameworks were calculated from hydrogen isotherms measured at 77 and 87 K and found to increase with M varying in the order Mn < Zn < Fe < Co < Cu < Ni. In all cases, the binding enthalpies, which lie in the range of 5.3-7.4 kJ/mol, are higher than the 4.7-5.2 kJ/mol measured for Zn4O(1,4-benzenedicarboxylate)3.     

The effect of amino acid deletions and substitutions in the longest loop of GFP

Background  

The effect of single and multiple amino acid substitutions in the green fluorescent protein (GFP) from Aequorea victoria has been extensively explored, yielding several proteins of diverse spectral properties. However, the role of amino acid deletions in this protein -as with most proteins- is still unknown, due to the technical difficulties involved in generating combinatorial in-phase amino acid deletions on a target region.     

Stabilization of a high energy molecular conformation by specific intermolecular forces, a novel planar benzylideneaniline system

The system containing six benzylideneanilines (BA) has been studied: Group 1: