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Synthesis of 1-thio-phytosphingolipid analogs by microwave promoted reactions of thiols and aziridine derivatives

Anna Alcaide, Amadeu Llebaria

Tetrahedron Letters 53 (16), 2137–2139, 2012

A practical and versatile method for the synthesis of 1-thio-phytosphingolipid analogs through regioselective nucleophilic ring-opening reactions of phytosphingosine aziridine derivatives with thiols is described. The reactions were carried out with N-acylaziridines and a variety of thiol compounds. Microwave irradiation highly improved the yield of the ring-opening reaction and the intermediate N-acyl adducts were converted into 1-S-phytosphingolipid analogs, such as phytoceramide and phytosphingosine derivatives.

 

In situ aldehyde generation for aldol addition reactions catalyzed by d-fructose-6-phosphate aldolase

Maria Mifsud, Anna Szekrényi, Jesús Joglar, Pere Clapés

Journal of Molecular Catalysis B: Enzymatic, 84, 102–107, 2012

In situ coupling of aldehyde generation, by a mild alcohol oxidation, with an enzymatic aldol addition reaction, mediated by d-fructose-6-phosphate aldolase (FSA) has been investigated as an approach to improve the performance of the process. Four sustainable oxidation methods compatible with the activity and stability of the enzymatic aldol addition have been assayed. Among them, the laccase/O2/2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and alcohol oxidase gave the best results for the N-Cbz-aminoethanol to N-Cbz-glycinal (53%) and furfuryl alcohol to furfural (89%), respectively, followed by the aldol addition with hydroxyacetone catalyzed by FSA A129S mutant.

 

Solvent-Free Model for Self-Assembling Amphiphilic Cyclodextrins. An Off-Lattice Monte Carlo Approach in Two Dimensions

Alessandro Patti, Roland Ramsch, Conxita Solans Marsà

J. Phys. Chem. B, Article ASAP, 116, 2687-2695, 2012

By performing off-lattice Monte Carlo simulations in a two-dimensional space, we investigate the aggregation behavior of model Bouquet-shaped amphiphilic cyclodextrins. These molecules are able to self-assemble into a variety of supramolecular structures, such as micelles, vesicles, and long double-layered filaments. At high packing fractions, inverted micellar phases and lamellar liquid crystals have also been observed. Despite the number of approximations and restrictions imposed in our model, where the solution degrees of freedom are kept implicit and only the main physicochemical details are considered, we are able to reproduce the self-assembling behavior of amphiphilic cyclodextrins in its essential and most characteristic picture. The calculations of the cluster size distribution, density profiles, and radial distribution functions permit the characterization of the aggregates formed in the self-assembly process.

 

Continuous degradation of a mixture of sulfonamides by Trametes versicolor and identification of metabolites from sulfapyridine and sulfathiazole

Carlos E. Rodríguez-Rodríguez, Ma. Jesús García-Galán, Paqui Blánquez, M. Silvia Díaz-Cruz, Damià Barceló, Glòria Caminal, Teresa Vicent

Journal of Hazardous Materials, 213– 214, 347– 354, 2012

 
 
 
In this study, we assessed the degradation of the sulfonamides sulfapyridine (SPY) and sulfathiazole (STZ) by the white-rot fungus Trametes versicolor. Complete degradation was accomplished in fungal cultures at initial pollutant concentrations of approximately 10 mg L-1, although a longer period of time was needed to completely remove STZ in comparison to SPY. When cytochrome P450 inhibitors were added to the fungal cultures, STZ degradation was partially suppressed, while no additional effect was observed for SPY. Experiments with purified laccase and laccase mediators caused the removal of greater than 75% of each antibiotic. Ultra-performance liquid chromatography-quadupole time of flight mass spectrometry (UPLC-QqTOF-MS) analyses allowed the identification of a total of eight degradation intermediates of SPY in both the in vivo and the laccase experiments, being its desulfonated moiety the commonly detected product. For STZ, a total of five products were identified. A fluidized bed reactor with T. versicolor pellets degraded a mixture of sulfonamides (SPY, STZ and sulfamethazine, SMZ) by greater than 94% each at a hydraulic residence time of 72 h. Because wastewater contains many diverse pollutants, these results highlight the potential of T. versicolor as a bioremediation agent not only for the removal of antibiotics but also for the elimination of a wide range of contaminants.
 

A comparative life cycle assessment of two treatment technologies for the Grey Lanaset G textile dye: biodegradation by Trametes versicolor and granular activated carbon adsorption

Xavier Gabarrell, Mercè Font, Teresa Vicent, Gloria Caminal, Montserrat Sarrà, Paqui Blánquez

Int. J. Life Cycle Assess., 17, 613–624, 2012

The aim of this study is to use life cycle assessment (LCA) to compare the relative environmental performance of the treatment using Trametes versicolor with a common method such as activated carbon adsorption. This comparison will evaluate potential environmental impacts of the two processes. This work compiles life cycle inventory data for a biological process that may be useful for other emergent biotechnological processes in water and waste management. LCA was performed to evaluate the use of a new technology for the removal of a model metal-complex dye, Grey Lanaset G, from textile wastewater by means of the fungus T. versicolor. This biological treatment was compared with a conventional coal-based activated carbon adsorption treatment to determine which alternative is preferable from an environmental point of view.

 

Nanogold probe enhanced Surface Plasmon Resonance immunosensor for improved detection of antibiotic residues

Fátima Fernández, Francisco Sánchez-Baeza, M.-Pilar Marco

Biosensors and Bioelectronics, 34, 151– 158, 2012

An exhaustive study is reported on the effect that antibody nanogold probes produce on the performance of a Surface Plasmon Resonance (SPR) immunosensor. The paper studies the improvement that different nanogold probes prepared at different antibody:gold nanoparticle (IgG:AuNP) ratios and AuNP sizes produce on the maximum signal and detectability of a simple SPR immunosensor developed to analyze fluoroquinolone (FQ) antibiotic residues (SPReeta system). The investigation compares the features of sensor enhanced formats using both, secondary and primary nanogold probes (anti-IgG and IgG coupled to AuNP, on double and single-antibody immunochemical assay steps, respectively), in respect to the unenhanced format. For this purpose, a reproducible bioconjugation procedure for preparing gold biohybrid nanoparticles has been established, involving the formation of a mixed self-assembled monolayer (m-SAM) with PEGylated cross-linkers around the AuNP followed by the covalent attachment of the antibodies. The procedure allows controlling the IgG:AuNP ratio of the nanogold probes on a reproducible manner and the functionalized NPs have been found to be stable during assay and storage. Both formats, using secondary and primary nanogold probes, are excellent strategies to improve immunosensor detectability. Thus, using anti-IgG-AuNP, the detectability could be improved by a factor of 14 (LOD 0.07 ± 0.01 μg L−1 vs. 0.98 ± 0.38 μg L−1) reducing at the same time the amount of primary antibody used (30,000 vs. 1000 dilution factor). Likewise, the format using IgG-AuNP also allows improving detectability (LOD 0.11 ± 0.01 μg L−1), but reducing the number of needed steps.

 

Synthesis of a New Deuterium-Labeled Phytol as a Tool for Biosynthetic Studies

Lourdes Muñoz, Angel Guerrero

Synthesis, 44, 862–864, 2012

An efficient and stereoselective synthesis of a new deuterium-labeled phytol as a useful tracer in biosynthetic processes is presented.

 

Receptors for Zwitterionic Species

S. V. Luis, I. Alfonso, F. Galindo

Supramolecular Chemistry: From Molecules to Nanomaterials. 1259-1280, 2012. Edited by Philip A. Gale and Jonathan W. Steed. 2012 John Wiley & Sons, Ltd. ISBN: 978-0-470-74640-0.

The appropriate design of receptors to selectively interact with a given zwitterionic species requires a careful balance between a complex set of factors, some of which seem to act in opposite directions. A reasonable structure developed for this purpose should be a ditopic receptor containing two well-defined sites, one being able to interact with cations and the other being able to interact with anions. Each of the sites needs to be optimized for its specific function, but, at the same time, they need to be properly located within the corresponding molecule, providing relative orientations, distances, and shapes matching those of the zwitterionic species to be recognized.

 

Inhibition of deleterious chronic wound enzymes with plant polyphenols

M. Díaz-González, G. Rocasalbas, A. Francesko, S. Touriño, J.L. Torres, Tz. Tzanov

Biocat. Biotrans.  30, 102-110, 2012

The chronic wound environment is characterized by high concentrations of reactive oxygen species (ROS) and elevated levels of myeloperoxidase (MPO) and collagenases, together impairing the healing process. Therefore, the management of chronic wounds at a molecular level requires the synergistic use of antioxidants, MPO and collagenase inhibitors to simultaneously target multiple factors from wound pathogenesis. In this study, a polyphenolic extract from Hamamelis virginiana plant, rich in condensed and hydrolysable oligomeric tannins, was evaluated as an inhibitor of MPO and collagenase. In addition to efficient scavengers of radical and non-radical reactive species, H. virginiana polyphenols were found to act as substrates in the MPO peroxidase cycle, preventing the accumulation of ROS in the chronic wound site. Furthermore, it was also found that the plant exerts an irreversible inhibitory effect on collagenase activity (IC50 = 75 ± 10 μg/mL).

 

Dynamic Fingerprints of Protein Thermostability Revealed by Long Molecular Dynamics

Enrique Marcos, Aurora Jiménez, and Ramon Crehuet

J. Chem. Theory Comput., 8, 1129−1142, 2012

The dynamical requirements for protein thermostability are a subject of intense debate since different techniques are sensitive to different dynamical processes. The present investigation arises from a neutron scattering experiment pointing to the lower temperature dependence of the flexibility of thermophilic proteins as a mechanism of enhanced thermostability. By means of 200 ns molecular dynamics simulations at different temperatures, we have investigated the differences in internal dynamics of the thermo-mesophilic pair of proteins studied in the experiment. The present work exceeds the time scales explored by the experiment and former studies on other thermo-mesophilic pairs by several orders of magnitude. Our simulations confirm the different thermal behavior observed in the experiment and suggest that both reduced coil segments and salt bridge interactions contribute to lowering the increase in flexibility with temperature. Moreover, the mesophilic protein exhibits a more heterogeneous distribution of residue mobilities involving more local motions. We suggest that the more collective motions of the thermophilic protein underlie a broader energy landscape.

 


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