bluuebunny/crossref_metadata_2025_split huggingface dataset:
The importance of pyroglutamate in cellulase Cel7A
Authors: Dana Craig M. , Dotson‐Fagerstrom Alexandra , Roche Christine M. , Kal Sarala M. , Chokhawala Harshal A. , Blanch Harvey W. , Clark Douglas S. 
Published: December 2013

ABSTRACTThe commercialization of lignocellulosic biofuels relies in part on the ability to engineer cellulase enzymes to have properties compatible with practical processing conditions. The cellulase Cel7A has been a common engineering target because it is present in very high concentrations in commercial cellulase cocktails. Significant effort has thus been focused on its recombinant expression. In particular, the yeast Saccharomyces cerevisiae has often been used both in the engineering and basic study of Cel7A. However, the expression titer and extent of glycosylation of Cel7A expressed in S. cerevisiae vary widely for Cel7A genes from different organisms, and the recombinant enzymes tend to be less active and less stable than their native counterparts. These observations motivate further study of recombinant expression of Cel7A in S. cerevisiae. Here, we compare the properties of Cel7A from Talaromyces emersonii expressed in both the budding yeast S. cerevisiae and the filamentous fungus Neurospora crassa. The Cel7A expressed in N. crassa had a higher melting temperature (by 10°C) and higher specific activity (twofold at 65°C) than the Cel7A expressed in S. cerevisiae. We examined several post‐translational modifications and found that the underlying cause of this disparity was the lack of N‐terminal glutamine cyclization in the Cel7A expressed in S. cerevisiae. Treating the enzyme in vitro with glutaminyl cyclase improved the properties of Cel7A expressed in S. cerevisiae to match those of Cel7A expressed in N. crassa. Biotechnol. Bioeng. 2014;111: 842–847. © 2013 Wiley Periodicals, Inc.
Promoting extracellular matrix remodeling via ascorbic acid enhances the survival of primary ovarian follicles encapsulated in alginate hydrogels
Authors: Tagler David , Makanji Yogeshwar , Tu Tao , Bernabé Beatriz Peñalver , Lee Raymond , Zhu Jie , Kniazeva Ekaterina , Hornick Jessica E. , Woodruff Teresa K. , Shea Lonnie D. 
Published: December 2013

ABSTRACTThe in vitro growth of ovarian follicles is an emerging technology for fertility preservation. Various strategies support the culture of secondary and multilayer follicles from various species including mice, non‐human primate, and human; however, the culture of early stage (primary and primordial) follicles, which are more abundant in the ovary and survive cryopreservation, has been limited. Hydrogel‐encapsulating follicle culture systems that employed feeder cells, such as mouse embryonic fibroblasts (MEFs), stimulated the growth of primary follicles (70–80 µm); yet, survival was low and smaller follicles (<70 µm) rapidly lost structure and degenerated. These morphologic changes were associated with a breakdown of the follicular basement membrane; hence, this study investigated ascorbic acid based on its role in extracellular matrix (ECM) deposition/remodeling for other applications. The selection of ascorbic acid was further supported by a microarray analysis that suggested a decrease in mRNA levels of enzymes within the ascorbate pathway between primordial, primary, and secondary follicles. The supplementation of ascorbic acid (50 µg/mL) significantly enhanced the survival of primary follicles (<80 µm) cultured in alginate hydrogels, which coincided with improved structural integrity. Follicles developed antral cavities and increased to diameters exceeding 250 µm. Consistent with improved structural integrity, the gene/protein expression of ECM and cell adhesion molecules was significantly changed. This research supports the notion that modifying the culture environment (medium components) can substantially enhance the survival and growth of early stage follicles. Biotechnol. Bioeng. 2014;111: 1417–1429. © 2013 Wiley Periodicals, Inc.
Simultaneous uptake of lignocellulose‐based monosaccharides by Escherichia coli
Authors: Jarmander Johan , Hallström Björn M. , Larsson Gen 
Published: December 2013

ABSTRACTLignocellulosic waste is a naturally abundant biomass and is therefore an attractive material to use in second generation biorefineries. Microbial growth on the monosaccharides present in hydrolyzed lignocellulose is however associated with several obstacles whereof one is the lack of simultaneous uptake of the sugars. We have studied the aerobic growth of Escherichia coli on D‐glucose, D‐xylose, and L‐arabinose and for simultaneous uptake to occur, both the carbon catabolite repression mechanism (CCR) and the AraC repression of xylose uptake and metabolism had to be removed. The strain AF1000 is a MC4100 derivative that is only able to assimilate arabinose after a considerable lag phase, which is unsuitable for commercial production. This strain was successfully adapted to growth on L‐arabinose and this led to simultaneous uptake of arabinose and xylose in a diauxic growth mode following glucose consumption. In this strain, a deletion in the phosphoenolpyruvate:phosphotransferase system (PTS) for glucose uptake, the ptsG mutation, was introduced. The resulting strain, PPA652ara simultaneously consumed all three monosaccharides at a maximum specific growth rate of 0.59 h−1, 55% higher than for the ptsG mutant alone. Also, no residual sugar was present in the cultivation medium. The potential of PPA652ara is further acknowledged by the performance of AF1000 during fed‐batch processing on a mixture of D‐glucose, D‐xylose, and L‐arabinose. The conclusion is that without the removal of both layers of carbon uptake control, this process results in accumulation of pentoses and leads to a reduction of the specific growth rate by 30%. Biotechnol. Bioeng. 2014;111: 1108–1115. © 2014 Wiley Periodicals, Inc.
Multi‐analyte profile analysis of plasma immune proteins: altered expression of peripheral immune factors is associated with neuropsychiatric symptom severity in adults with and without chronic hepatitis C virus infection
Authors: Huckans Marilyn , Fuller Bret E. , Olavarria Hannah , Sasaki Anna W. , Chang Michael , Flora Kenneth D. , Kolessar Michael , Kriz Daniel , Anderson Jeanne R. , Vandenbark Arthur A. , Loftis Jennifer M. 
Published: December 2013

AbstractBackgroundThe purpose of this study was to characterize hepatitis C virus (HCV)‐associated differences in the expression of 47 inflammatory factors and to evaluate the potential role of peripheral immune activation in HCV‐associated neuropsychiatric symptoms—depression, anxiety, fatigue, and pain. An additional objective was to evaluate the role of immune factor dysregulation in the expression of specific neuropsychiatric symptoms to identify biomarkers that may be relevant to the treatment of these neuropsychiatric symptoms in adults with or without HCV.MethodsBlood samples and neuropsychiatric symptom severity scales were collected from HCV‐infected adults (HCV+, n = 39) and demographically similar noninfected controls (HCV−, n = 40). Multi‐analyte profile analysis was used to evaluate plasma biomarkers.ResultsCompared with HCV− controls, HCV+ adults reported significantly (P < 0.050) greater depression, anxiety, fatigue, and pain, and they were more likely to present with an increased inflammatory profile as indicated by significantly higher plasma levels of 40% (19/47) of the factors assessed (21%, after correcting for multiple comparisons). Within the HCV+ group, but not within the HCV− group, an increased inflammatory profile (indicated by the number of immune factors > the LDC) significantly correlated with depression, anxiety, and pain. Within the total sample, neuropsychiatric symptom severity was significantly predicted by protein signatures consisting of 4–10 plasma immune factors; protein signatures significantly accounted for 19–40% of the variance in depression, anxiety, fatigue, and pain.ConclusionsOverall, the results demonstrate that altered expression of a network of plasma immune factors contributes to neuropsychiatric symptom severity. These findings offer new biomarkers to potentially facilitate pharmacotherapeutic development and to increase our understanding of the molecular pathways associated with neuropsychiatric symptoms in adults with or without HCV.
White matter integrity is associated with alcohol cue reactivity in heavy drinkers
Authors: Monnig Mollie A. , Thayer Rachel E. , Caprihan Arvind , Claus Eric D. , Yeo Ronald A. , Calhoun Vince D. , Hutchison Kent E. 
Published: December 2013

AbstractNeuroimaging studies have shown that white matter damage accompanies excessive alcohol use, but the functional correlates of alcohol‐related white matter disruption remain unknown. This study applied tract‐based spatial statistics (TBSS) to diffusion tensor imaging (DTI) data from 332 heavy drinkers (mean age = 31.2 ± 9.4; 31% female) to obtain averaged fractional anisotropy (FA) values of 18 white matter tracts. Statistical analyses examined correlations ofFAvalues with blood‐oxygenation‐level‐dependent (BOLD) response to an alcohol taste cue, measured with functional magnetic resonance imaging (fMRI).FAvalues of nine white matter tracts (anterior corona radiata, body of corpus callosum, cingulate gyrus, external capsule, fornix, inferior frontooccipital fasciculus, posterior corona radiata, retrolenticular limb of internal capsule, and superior longitudinal fasciculus) were significantly, negatively correlated withBOLDactivation in medial frontal gyrus, parahippocampal gyrus, fusiform gyrus, cingulum, thalamus, caudate, putamen, insula, and cerebellum. The inverse relation between white matter integrity and functional activation during the alcohol taste cue provides support for the hypothesis that lower white matter integrity in frontoparietal and corticolimbic networks is a factor in loss of control over alcohol consumption.
Uniform Ag/AgCl Necklace‐Like Nano‐Heterostructures: Fabrication and Highly Efficient Plasmonic Photocatalysis
Authors: Jia Changchao , Yang Ping , Huang Baibiao 
Published: December 2013

AbstractAg/AgCl necklace‐like nano‐heterostructures with an average diameter of 55 nm were prepared by a facile in situ oxidation process. As a result of the presence of multiple crystalline Ag nanowires with lots of grain boundaries, uniform Ag/AgCl necklace‐like heterostructures can be successfully obtained in the presence of polyvinylpyrrolidone (PVP). Ag and AgCl are evenly distributed in the necklace‐like structures, which were divided into a number of tiny units that consisted of Ag and AgCl and enabled easy electron transfer. In contrast, a loose Ag/AgCl structure with large particles was prepared without the addition of PVP. A formation mechanism of the Ag/AgCl nano‐heterostructures was proposed. Furthermore, the molar ratio of Ag and AgCl plays an important role in the photocatalytic activity of the nano‐heterostructures, which can be tuned simply. The results of photocatalytic investigations demonstrate that the Ag/AgCl heterostructures with an 85 % AgCl component have an excellent activity for the decomposition of organic pollutants and water splitting to produce oxygen.
Pt3Co Concave Nanocubes: Synthesis, Formation Understanding, and Enhanced Catalytic Activity toward Hydrogenation of Styrene
Authors: Wang Chenyu , Lin Cuikun , Zhang Lihua , Quan Zewei , Sun Kai , Zhao Bo , Wang Feng , Porter Nathan , Wang Yuxuan , Fang Jiye 
Published: December 2013

AbstractWe report a facile synthesis route to prepare high‐quality Pt3Co nanocubes with a concave structure, and further demonstrate that these concave Pt3Co nanocubes are terminated with high‐index crystal facets. The success of this preparation is highly dependent on an appropriate nucleation process with a successively anisotropic overgrowth and a preservation of the resultant high‐index planes by control binding of oleyl‐amine/oleic acid with a fine‐tuned composition. Using a hydrogenation of styrene as a model reaction, these Pt3Co concave nanocubes as a new class of nanocatalysts with more open structure and active atomic sites located on their high‐index crystallographic planes exhibit an enhanced catalytic activity in comparison with low‐indexed surface terminated Pt3Co nanocubes in similar size.
Chiral Modification of Platinum by Co‐Adsorbed Cinchonidine and Trifluoroacetic Acid: Origin of Enhanced Stereocontrol in the Hydrogenation of Trifluoroacetophenone
Authors: Meemken Fabian , Baiker Alfons , Schenker Sebastian , Hungerbühler Konrad 
Published: December 2013

AbstractCinchonidine (CD) adsorbed onto a platinum metal catalyst leads to rate acceleration and induces strong stereocontrol in the asymmetric hydrogenation of trifluoroacetophenone. Addition of catalytic amounts of trifluoroacetic acid (TFA) significantly enhances the enantiomeric excess from 50 to 92 %. The origin of the enantioselectivity bestowed by co‐adsorbed CD and TFA is investigated by using in situ attenuated total reflection infrared spectroscopy and modulation excitation spectroscopy. Molecular interactions between the chiral modifier (CD), acid additive (TFA) and the trifluoro‐activated substrate at the solid–liquid interface are elucidated under conditions relevant to catalytic hydrogenations, that is, on a technical Pt/Al2O3 catalyst in the presence of H2 and solvent. Monitoring of the unmodified and modified surface during the hydrogenation provides an insight into the phenomenon of rate enhancement and the crucial interactions of CD with the ketone, corresponding product alcohol, and TFA. Comparison of the diastereomeric interactions occurring on the modified surface and in the liquid solution shows a striking difference for the chiral preferences of CD. The spectroscopic data, in combination with calculations of molecular structures and energies, sheds light on the reaction mechanism of the heterogeneous asymmetric hydrogenation of trifluoromethyl ketones and the involvement of TFA in the diastereomeric intermediate surface complex: the quinuclidine N atom of the adsorbed CD forms an NHO‐type hydrogen‐bonding interaction not only with the trifluoro‐activated ketone but also with the corresponding alcohol and the acid additive. Strong evidence is provided that it is a monodentate acid/base adduct in which the carboxylate of TFA resides at the quinuclidine N‐atom of CD, which imparts a better stereochemical control.
Controlling Protein Crystal Nucleation by Droplet‐Based Microfluidics
Authors: Maeki Masatoshi , Teshima Yuki , Yoshizuka Saori , Yamaguchi Hiroshi , Yamashita Kenichi , Miyazaki Masaya 
Published: December 2013

AbstractHerein, we demonstrate the potential of droplet‐based microfluidics for controlling protein crystallization and generating single‐protein crystals. We estimated the critical droplet size for obtaining a single crystal within a microdroplet and investigated the crystallization of four model proteins to confirm the effect of protein molecular diffusion on crystallization. A single crystal was obtained in microdroplets smaller than the critical size by using droplet‐based microfluidics. In the case of thaumatin crystallization, a single thaumatin crystal was obtained in a 200 μm droplet even with high supersaturation. In the case of ferritin crystallization, the nucleation profile of ferritin crystals had a wider distribution than the nucleation profiles of lysozyme, thaumatin, and glucose isomerase crystallization. We found that the droplet‐based microfluidic approach was able to control the nucleation of a protein by providing control over the crystallization conditions and the droplet size, and that the diffusion of protein molecules is a significant factor in controlling the nucleation of protein crystals in droplet‐based microfluidics.
Sequence‐Specific DNA Alkylation Targeting for Kras Codon 13 Mutation by Pyrrole–Imidazole Polyamide seco‐CBI Conjugates
Authors: Taylor Rhys Dylan , Asamitsu Sefan , Takenaka Tomohiro , Yamamoto Makoto , Hashiya Kaori , Kawamoto Yusuke , Bando Toshikazu , Nagase Hiroki , Sugiyama Hiroshi 
Published: December 2013

AbstractHairpin N‐methylpyrrole‐N‐methylimidazole polyamide seco‐CBI conjugates 2–6 were designed for synthesis by Fmoc solid‐phase synthesis, and their DNA‐alkylating activities against the Kras codon 13 mutation were compared by high‐resolution denaturing gel electrophoresis with 225 base pair (bp) DNA fragments. Conjugate 5 had high reactivity towards the Kras codon 13 mutation site, with alkylation occurring at the A of the sequence 5′‐ACGTCACCA‐3′ (site 2), including minor 1 bp‐mismatch alkylation against wild type 5′‐ACGCCACCA‐3′ (site 3). Conjugate 6, which differs from conjugate 5 by exchanging one Py unit with a β unit, showed high selectivity but only weakly alkylated the A of 5′‐ACGTCACCA‐3′ (site 2). The hairpin polyamide seco‐CBI conjugate 5 thus alkylates according to Dervan′s pairing rule with the pairing recognition which β/β pair targets T–A and A–T pairs. SPR and a computer‐minimized model suggest that 5 binds to the target sequence with high affinity in a hairpin conformation, allowing for efficient DNA alkylation.
Equilibrium Shift in Solution: Molecular Shape Recognition and Precipitation of a Synthetic Double Helix Using Helicene‐Grafted Silica Nanoparticles
Authors: Miyagawa Masamichi , Ichinose Wataru , Yamaguchi Masahiko 
Published: December 2013

AbstractChiral silica nanoparticles (70 nm) grafted with (P)‐helicene recognized the molecular shape of double helix and random coil (P)‐ethynylhelicene oligomers in solution. A mixture of the (P)‐nanoparticles and double helix precipitated much faster than a mixture of the (P)‐nanoparticles and random coil, and the precipitate contained only the double helix. The mixture of the (P)‐nanoparticles and (P)‐ethynylhelicene pentamer reversibly dispersed in trifluoromethylbenzene upon heating at 70 °C and precipitated upon cooling at 25 °C. When a 10:90 equilibrium mixture of the double helix and random coil in solution was treated with the (P)‐nanoparticles, the double helix was precipitated in 53 % yield and was accompanied by equilibrium shift.
Janus Microspheres for Visual Assessment of Molecular Interconnects
Authors: Fliedel Christophe , Faramarzi Vina , Rosa Vitor , Doudin Bernard , Braunstein Pierre 
Published: December 2013

AbstractA rigid S‐functionalized metalloligand is used to pair Janus Au‐coated silica microspheres and the resulting assemblies are assessed with optical microscopy. New Pd complexes provide stable molecular interconnects, and the metal centre controls the structure of the linker and provides the desired rigidity, by virtue of its well‐established coordination chemistry.
NAD(P)H‐Independent Asymmetric CC Bond Reduction Catalyzed by Ene Reductases by Using Artificial Co‐substrates as the Hydrogen Donor
Authors: Winkler Christoph K. , Clay Dorina , Entner Marcello , Plank Markus , Faber Kurt 
Published: December 2013

AbstractTo develop a nicotinamide‐independent single flavoenzyme system for the asymmetric bioreduction of CC bonds, four types of hydrogen donor, encompassing more than 50 candidates, were investigated. Six highly potent, cheap, and commercially available co‐substrates were identified that (under the optimized conditions) resulted in conversions and enantioselectivities comparable with, or even superior to, those obtained with traditional two‐enzyme nicotinamide adenine dinucleotide phosphate (NAD(P)H)‐recycling systems.
Tuning the Photophysical Properties of BODIPY Molecules by π‐Conjugation with Fischer Carbene Complexes
Authors: Chu Gong Ming , Guerrero‐Martínez Andrés , Fernández Israel , Sierra Miguel Ángel 
Published: December 2013

AbstractThe synthesis, structure, and photophysical properties of novel BODIPY–Fischer alkoxy‐, thio‐, and aminocarbene dyads are reported. The BODIPY chromophore is directly attached to the carbene ligand by an ethylenic spacer, thus forming donor–bridge–acceptor π‐extended systems. The extension of the π‐conjugation is decisive in the equilibrium geometries of the dyads and is clearly reflected in the corresponding absorption and emission spectra. Whereas the BODIPY fragment is mainly isolated in aminocarbene complexes, it is fully conjugated in alkoxycarbene derivatives. The former thus exhibit the characteristic photophysical properties of BODIPY units, whereas complete suppression of the BODIPY fluorescence emission is observed in the latter, as a direct consequence of the strong electron‐accepting character of the (CO)5MC moiety. As the π‐acceptor character of the metal–carbene group can be modified, the electronic properties of the conjugated BODIPY can be tuned. Density functional calculations have been carried out to gain insight into the photophysical properties.
FeCl3‐Mediated Three‐Component Cascade Reaction: An Effective Approach to the Construction of Highly Functionalized Pyrrolo[1,2‐c]quinazolinones
Authors: Zheng Hu‐Fei , Yu Zhi‐Hua , Yuan Wei , Tang Zi‐Long , Clough John , Gu Yu‐Cheng , Shi De‐Qing 
Published: December 2013

AbstractAn unexpected FeCl3‐mediated three‐component cascade reaction has been used to construct structurally diverse pyrrolo[1,2‐c]quinazolinone derivatives with potential biological activities. This method has advantages of mild conditions, simple work‐up, as well as wide substrate scope, which makes it a powerful approach to the synthesis of diverse pyrrolo[1,2‐c]quinazolinones. This cascade reaction involves 1,3‐dipolar cycloaddition between azomethine ylides and allenoates, followed by intramolecular nucleophilic addition in the presence of FeCl3. The obtained products could be easily transformed into derivatives with the pyrrolo[2,3‐c]quinazoline alkaloid skeleton.
Investigation of the Thermal Stability of the Carbon Framework of Graphene Oxide
Authors: Eigler Siegfried , Grimm Stefan , Hirsch Andreas 
Published: December 2013

AbstractIn this study, we use our recently prepared graphene oxide (GO) with an almost intact σ‐framework of carbon atoms (ai‐GO) to probe the thermal stability of the carbon framework for the first time. Ai‐GO exhibits few defects because CO2 formation is prevented during synthesis. Ai‐GO was thermally treated before chemical reduction and the resulting defect density in graphene was subsequently determined by statistical Raman microscopy. Surprisingly, the carbon framework of ai‐GO is stable in thin films up to 100 °C. Furthermore, we find evidence for an increase in the quality of ai‐GO upon annealing at 50 °C before reduction. The carbon framework of GO prepared according to the popular Hummers’ method (GO‐c) appears to be less stable and decomposition starts at 50 °C, which is qualitatively indicated by CO2‐trapping experiments in μm‐thin films. Information about the stability of GO is important for storing, processing, and using GO in many applications.
Gold(III)‐Mediated Contraction of Benzene to Cyclopentadiene: From p‐Benziporphyrin to Gold(III) True Tetraarylcarbaporphyrin
Authors: Szyszko Bartosz , Kupietz Kamil , Szterenberg Ludmiła , Latos‐Grażyński Lechosław 
Published: December 2013

AbstractThe reaction of p‐benziporphyrin, sodium tetrachloroaurate(III) dihydrate, and potassium carbonate in dichloromethane yielded gold(III) 5,10,15,20‐tetraaryl‐21‐carbaporphyrin owing to the contraction of p‐phenylene to cyclopentadiene. This molecule is the very first representative of a true 5,10,15,20‐tetraaryl‐21‐carbaporphyrin complex where four trigonal donor atoms are involved in equatorial coordination. The contraction adds an unprecedented route to numerous organic transformations of aromatic compounds catalyzed by simple gold(III) compounds. p‐Benziporphyrin provided the unique environment to alter the fundamental reactivity of the benzene unit facilitating its contraction to cyclopentadiene.