bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combinatorial Library Based Engineering of Candida antarctica Lipase A for Enantioselective Transacylation of sec‐Alcohols in Organic Solvent
Authors: Wikmark Ylva , Svedendahl Humble Maria , Bäckvall Jan‐E. 
Published: February 2015

AbstractA method for determining lipase enantioselectivity in the transacylation of sec‐alcohols in organic solvent was developed. The method was applied to a model library of Candida antarctica lipase A (CalA) variants for improved enantioselectivity (E values) in the kinetic resolution of 1‐phenylethanol in isooctane. A focused combinatorial gene library simultaneously targeting seven positions in the enzyme active site was designed. Enzyme variants were immobilized on nickel‐coated 96‐well microtiter plates through a histidine tag (His6‐tag), screened for transacylation of 1‐phenylethanol in isooctane, and analyzed by GC. The highest enantioselectivity was shown by the double mutant Y93L/L367I. This enzyme variant gave an E value of 100 (R), which is a dramatic improvement on the wild‐type CalA (E=3). This variant also showed high to excellent enantioselectivity for other secondary alcohols tested.
Fixierung und Freisetzung von intakten E4‐Tetraedern (E=P, As)
Authors: Spitzer Fabian , Sierka Marek , Latronico Mario , Mastrorilli Piero , Virovets Alexander V. , Scheer Manfred 
Published: February 2015

AbstractDurch die Reaktion von [NacnacCuCH3CN] mit weißem Phosphor (P4) und gelbem Arsen (As4) werden die Stabilisierung und der Einschluss von intakten E4‐Tetraedern realisiert, und es bilden sich die zweifach‐substituierten Komplexe [(NacnacCu)2(μ,η2:2‐E4)] (1 a: E=P, 1 b: E=As). Der monosubstituierte Komplex [NacnacCu(η2‐P4)] (2) wurde in einer Austauschreaktion von 1 a mit P4 detektiert und nur durch Aufarbeitung bei tiefen Temperaturen isoliert. Alle Produkte wurden umfassend spektroskopisch und kristallographisch charakterisiert. Die Bindungsverhältnisse in den Produkten als intakte E4‐Einheiten (E=P, As) wurden durch theoretische Studien bestätigt und experimentell durch die Pyridin‐geförderte Freisetzung der verbrückenden E4‐Tetraeder in 1 bewiesen.
Live‐cell MRI with Xenon Hyper‐CEST Biosensors Targeted to Metabolically Labeled Cell‐Surface Glycans
Authors: Witte Christopher , Martos Vera , Rose Honor May , Reinke Stefan , Klippel Stefan , Schröder Leif , Hackenberger Christian P. R. 
Published: February 2015

AbstractThe targeting of metabolically labeled glycans with conventional MRI contrast agents has proved elusive. In this work, which further expands the utility of xenon Hyper‐CEST biosensors in cell experiments, we present the first successful molecular imaging of such glycans using MRI. Xenon Hyper‐CEST biosensors are a novel class of MRI contrast agents with very high sensitivity. We designed a multimodal biosensor for both fluorescent and xenon MRI detection that is targeted to metabolically labeled sialic acid through bioorthogonal chemistry. Through the use of a state of the art live‐cell bioreactor, it was demonstrated that xenon MRI biosensors can be used to image cell‐surface glycans at nanomolar concentrations.
Porous Solids Arising from Synergistic and Competing Modes of Assembly: Combining Coordination Chemistry and Covalent Bond Formation
Authors: Dutta Ananya , Koh Kyoungmoo , Wong‐Foy Antek G. , Matzger Adam J. 
Published: February 2015

AbstractDesign and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material‐discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks.
Nickel‐Promoted Highly Regioselective Carboxylation of Aryl Ynol Ether and Its Application to the Synthesis of Chiral β‐Aryloxypropionic Acid Derivatives
Authors: Saito Nozomi , Sun Zhongdong , Sato Yoshihiro 
Published: February 2015

AbstractNickel(0)‐promoted carboxylation of aryl ynol ether proceeded in a highly regioselective manner to produce α‐substituted‐β‐aryloxyacrylic acid derivatives. The α‐substituted‐β‐aryloxyacrylic acids were transformed into the corresponding β‐aryloxypropionic acid derivative as an optically active form via rhodium‐catalyzed asymmetric hydrogenation.
Self‐Assembly of a Au16 Ring via Metal–Metal Bonding Interactions
Authors: Wang Ya‐Qing , Jiang Xuan‐Feng , Li Hao , Yu Shu‐Yan 
Published: February 2015

AbstractMetal–metal bonding interactions have been employed as an efficient strategy to generate a number of unique gold(I) metallo‐macrocycles with fascinating functions. The self‐assembly, crystal structure and emission property of novel nest‐like tetramer 14, namely, {[Au4(μ‐dppm)2(μ‐dctp2−)](BF4)2}4⋅(CH3CN)2 (dppm=bis(diphenylphosphino)methane, dctp2−=N,N′‐bis(dicarbodithioate)‐2,11‐diaza[3.3]paracyclophane) is reported. The complex has been characterized by single‐crystal X‐ray diffraction analysis, 1H NMR spectroscopy, 13C NMR spectroscopy, and CSI‐MS spectrometry. The aggregate demonstrates the sixteen gold(I) atoms are arranged in a ring with a circumference of 50.011(68) Å generated by AuI⋅⋅⋅AuI attractions. UV/visible and luminescence spectroscopy revealed that this AuI⋅⋅⋅AuI bonded metallo‐macrocycle exhibited yellow phosphorescence.
Synthesis and Predetermined Supramolecular Chirality of Carbohydrate‐Functionalized Perylene Bisimide Derivatives
Authors: Wang Ke‐Rang , Han Dan , Cao Guo‐Jing , Li Xiao‐Liu 
Published: February 2015

AbstractEight carbohydrate‐modified perylene bisimides (PBI‐4 lac‐2 lac, PBI‐4 lac‐2 Man, PBI‐4 lac‐2 Gal, PBI‐4 lac‐2 Mal, PBI‐4 Man‐2 Man, PBI‐4 Man‐2 lac, PBI‐4 Man‐2 Gal and PBI‐4 Man‐2 Mal) were synthesized, and the following predetermined supramolecular chirality rule was found: perylene bisimides modified with disaccharides (D‐lactose and D‐maltose) at the imide position generated right‐handed chirality, and those modified with monosaccharides (D‐mannose and D‐galactose) generated left‐handed chirality, when D‐lactose or D‐mannose was substituted in the bay positions of perylene bisimides with amide bonds as the linking spacers. These results may be because of the difference in the stacking angle of the perylene bisimide backbones induced by the steric effect and the additional hydrogen bonds between the disaccharide residues. This study provides an important design rule for predetermined chiral self‐assembly of perylene bisimides.
A General Direct Arylation of Polyfluoroarenes with Heteroaryl and Aryl Chlorides Catalyzed by Palladium Indolylphosphine Complexes
Authors: Yuen On Ying , Charoensak Mueangkaew , So Chau Ming , Kuhakarn Chutima , Kwong Fuk Yee 
Published: February 2015

AbstractThe first general examples of direct coupling of heteroaryl chlorides, especially substituted 2‐pyridyl chlorides which were previously found to be problematic, with electron‐deficient polyfluoroarenes are reported. Pd(OAc)2 associated with 3‐(dicyclohexylphosphino)‐2‐phenylindole L1 serves as the effective catalyst which allows the challenging direct coupling of heteroaryl chlorides and polyfluoroarenes. In addition to heterocycles, a wide range of non‐activated and activated aryl chlorides and alkenyl chlorides were also applicable under this catalyst system. A catalyst loading down to 1 mol % Pd can be achieved.
Dynamical quenching with non‐local α and downward pumping
Authors: Brandenburg A. , Hubbard A. , Käpylä P.J. 
Published: February 2015

AbstractIn light of new results, the one‐dimensional mean‐field dynamo model of Brandenburg & Käpylä (2007) with dynamical quenching and a nonlocal Babcock‐Leighton α effect is re‐examined for the solar dynamo. We extend the one‐dimensional model to include the effects of turbulent downward pumping (Kitchatinov & Olemskoy 2011), and to combine dynamical quenching with shear. We use both the conventional dynamical quenching model of Kleeorin & Ruzmaikin (1982) and the alternate one of Hubbard & Brandenburg (2011), and confirm that with varying levels of non‐locality in the α effect, and possibly shear as well, the saturation field strength can be independent of the magnetic Reynolds number. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular cloning and expression of a new α‐neoagarobiose hydrolase from Agarivorans gilvus WH0801 and enzymatic production of 3,6‐anhydro‐l‐galactose
Authors: Liu Nan , Yang Meng , Mao Xiangzhao , Mu Bozhong , Wei Dongzhi 
Published: February 2015

AbstractA new α‐neoagarobiose hydrolase (NABH) called AgaWH117 was cloned from Agarivorans gilvus WH0801. The gene encoding this hydrolase consists of 1,086 bp and encodes a protein containing 361 amino acids. This new NABH showed 74% amino acid sequence identity with other known NABHs. The molecular mass of the recombinant AgaWH117 was estimated to be 41 kDa. Purified AgaWH117 showed endolytic activity during neoagarobiose degradation, yielding 3,6‐anhydro‐l‐galactose (l‐AHG) and d‐galactose as products. It showed a maximum activity at a temperature of 30 °C and a pH of 6.0 and was stable at temperatures below 30 °C. Its Km and Vmax values were 2.094 mg/mL and 6.982 U/mg, respectively. The cloning strategy used and AgaWH117 isolated in this study will provide information on the saccharification process of marine biomass. This study provides a method to produce l‐AHG from agarose by using AgaWH117 without an acid and describes its one‐step purification by using Bio‐Gel P2 chromatography.
Spectroscopic study of the interaction between adenosine disodium triphosphate and gatifloxacin–Al3+ complex and its analytical application
Authors: Kamruzzaman Mohammad , Faruqui A. Nayeem , Hossain Mohammed Ifteker , Lee Sang Hak 
Published: February 2015

AbstractA new and sensitive spectrofluorimetric method has been proposed to determine trace amount of adenosine disodium triphosphate (ATP). The method is based on the fluorimetric interaction between gatifloxacin (GFLX)–aluminium (III) (Al3+) complex and ATP and studied using UV‐visible and fluorescence spectroscopy. Weak luminescence spectra of Al3+ were enhanced after complexation with GFLX at 423 nm upon excitation at 272 nm due to energy transfer from the ligand to the Al3+ ion. It was observed that the FL emission spectrum of GFLX–Al3+ was enhanced significantly by the addition of ATP. Under the optimal conditions, the enhancement of FL intensity at 423 nm was responded linearly with the concentration of ATP in the range 1.3 × 10–10 – 1.0 × 10–8 mol L–1 with correlation coefficient (r) of 0.9981. The limit of detection (LOD) was found to be 1.1 × 10–11 mol L–1 for ATP with the standard deviation (RSD) of 1.21% for five repeated measurement of 2.3 × 10–8 mol L–1 ATP. The presented method is simple, sensitive, free from coexisting interferents and can be applied successfully to determine ATP in the real samples. Copyright © 2015 John Wiley & Sons, Ltd.
Plant‐made vaccines against West Nile virus are potent, safe, and economically feasible
Authors: Chen Qiang 
Published: February 2015

AbstractThe threat of West Nile virus (WNV) epidemics with increasingly severe neuroinvasive infections demands the development and licensing of effective vaccines. To date, vaccine candidates based on inactivated, live‐attenuated, or chimeric virus, and viral DNA and WNV protein subunits have been developed. Some have been approved for veterinary use or are under clinical investigation, yet no vaccine has been licensed for human use. Reaching the milestone of a commercialized human vaccine, however, may largely depend on the economics of vaccine production. Analysis suggests that currently only novel low‐cost production technologies would allow vaccination to outcompete the cost of surveillance and clinical treatment. Here, we review progress using plants to address the economic challenges of WNV vaccine production. The advantages of plants as hosts for vaccine production in cost, speed and scalability, especially those of viral vector‐based transient expression systems, are discussed. The progress in developing WNV subunit vaccines in plants is reviewed within the context of their expression, characterization, downstream processing, and immunogenicity in animal models. The development of vaccines based on enveloped and non‐enveloped virus‐like particles is also discussed. These advancements suggest that plants may provide a production platform that offers potent, safe and affordable human vaccines against WNV.
Rational and efficient site‐directed mutagenesis of adenylation domain alters relative yields of luminmide derivatives in vivo
Authors: Bian Xiaoying , Plaza Alberto , Yan Fu , Zhang Youming , Müller Rolf 
Published: February 2015

ABSTRACTCloning and engineering of natural product biosynthetic pathways followed by heterologous expression in a tractable host is a widely used approach for expression and genetic modification of microbial secondary metabolites. Herein, we employed ccdB counterselection combined with oligonucleotide‐mediated recombineering to efficiently create point mutations in a complex nonribosomal peptide synthetase (NRPS) from Photorabdus luminescens directing the biosynthesis of luminmides. After in depth analysis of the luminmide production profile from the native NRPS, single and double point mutations were rationally constructed within the adenylation (A) domain from NRPS module 3 which turned out to have a broad substrate tolerance. Expression of mutated versions of the 15.6 kb NRPS gene plu3263 in E. coli led to alterations in luminmide production profiles and allowed to direct the biosynthesis towards certain derivatives. These results demonstrate the suitability of counterselection recombineering for site‐directed mutagenesis of complex expression constructs, e.g., genes encoding NRPS biosynthetic pathways in multi‐copy plasmids. Biotechnol. Bioeng. 2015;112: 1343–1353. © 2015 Wiley Periodicals, Inc.
Überlebensstrategien von Regenwaldameisen
Authors: Maschwitz Ulrich , Moog Joachim 
Published: February 2015

AbstractDie heftigen Regenfälle in den feuchten Tropen stellen Pflanzen und Tiere vor besondere Herausforderungen. Ameisen haben unterschiedliche Anpassungen gegen Überflutungen entwickelt. Von der Floßbildung bis zu verschiedenen Methoden der Nestentwässerung reichen die Maßnahmen gegen Hochwasser. In der Gezeitenzone werden Nester wasserdicht verschlossen, dabei reagieren die Ameisen mit physiologischen Anpassungen auf den Sauerstoffmangel. In einer obligaten Symbiose zwischen einer carnivoren Kannenpflanze und einer Rossameise hat sich ein einzigartiges Zusammenleben entwickelt, bei der die Partnerameise unbeschadet in dem enzymhaltigen Kannenwasser schwimmt und nach Mückenlarven und ertrunkenen Beutetieren taucht.
Väterliche Mitgift für die Zygote
Authors: Kronberg Inge 
Published: February 2015

AbstractDas Leben jedes mehrzelligen Organismus beginnt mit der Verschmelzung von Ei‐ und Spermienzelle zur Zygote. Die Beiträge der maternalen und paternalen Keimzellen zur Zygote sind dabei recht unterschiedlich: Die Eizelle liefert neben dem haploiden mütterlichen Chromosomensatz auch Zellplasma und Mitochondrien, die Spermienzelle scheinbar nur den haploiden väterlichen Chromosomensatz. Die Entdeckung winziger paternaler RNA‐Schnipsel, die von Spermienzellen auf die Zygote übertragen werden, ist insofern eine Überraschung. Ähnlich wie die maternalen Faktoren kann diese Mitgift nicht nur bei der Entwicklung der Zygote eine Rolle spielen, sondern auch in die epigenetische Vererbung eingreifen.
Determination of GDC‐0980 (apitolisib), a small molecule dual phosphatidylinositide 3‐kinase/mammalian target of rapamycin inhibitor in dog plasma by LC‐MS/MS to support a GLP toxicology study
Authors: Ding Xiao , Salphati Laurent , Kim Amy , Morinello Eric , Wong Lisa , Pang Jodie , Percey Shaundel , Meng Min , Reuschel Scott , Dean Brian 
Published: February 2015

AbstractAn LC‐MS/MS method for the determination of GDC‐0980 (apitolisib) concentrations in dog plasma has been developed and validated for the first time to support pre‐clinical drug development. Following protein precipitation with acetonitrile, the resulting samples were analyzed using reverse‐phase chromatography on a Metasil AQ column. The mass analysis was performed on a triple quadruple mass spectrometer coupled with an electrospray interface in positive ionization mode. The selected reaction monitoring transitions monitored were m/z 499.3 → 341.1 for GDC‐0980 and m/z 507.3 → 341.1 for IS. The method was validated over the calibration curve range 0.250–250 ng/mL with linear regression and 1/x2 weighting. Relative standard deviation (RSD) ranged from 0.0 to 10.9% and accuracy ranged from 93.4 to 113.6% of nominal. Stable‐labeled internal standard GDC‐0980‐d8 was used to minimize matrix effects. This assay was used for the measurement of GDC‐0980 dog plasma concentrations to determine toxicokinetic parameters after oral administration of GDC‐0980 (0.03, 0.1 and 0.3 mg/kg) to beagle dogs in a GLP toxicology study. Peak concentration ranged from 3.23 to 84.9 ng/mL. GDC‐0980 was rapidly absorbed with a mean time to peak concentration ranging from 1.3 to 2.4 h. Mean area under the concentration–time curve from 0 to 24 hours ranged from 54.4 to 542 ng h/mL. Copyright © 2015 John Wiley & Sons, Ltd.
Determination of triapine, a ribonucleotide reductase inhibitor, in human plasma by liquid chromatography tandem mass spectrometry
Authors: Feng Ye , Kunos Charles A. , Xu Yan 
Published: February 2015

AbstractTriapine is an inhibitor of ribonucleotide reductase (RNR). Studies have shown that triapine significantly decreases the activity of RNR and enhanced the radiation‐mediated cytotoxicity in cervical and colon cancer. In this work, we have developed and validated a selective and sensitive LC‐MS/MS method for the determination of triapine in human plasma. In this method, 2‐[(3‐fluoro‐2‐pyridinyl)methylene] hydrazinecarbothioamide (NSC 266749) was used as the internal standard (IS); plasma samples were prepared by deproteinization with acetonitrile; tripaine and the IS were separated on a Waters Xbridge Shield RP18 column (3.5 µm; 2.1 × 50 mm) using a mobile phase containing 25.0% methanol and 75.0% ammonium bicarbonate buffer (10.0 mm, pH 8.50; v/v); column eluate was monitored by positive turbo‐ionspray tandem mass spectrometry; and quantitation of triapine was carried out in multiple‐reaction‐monitoring mode. The method developed had a linear calibration range of 0.250–50.0 ng/mL with correlation coefficient of 0.999 for triapine in human plasma. The IS‐normalized recovery and the IS‐normalized matrix factor of triapine were 101–104% and 0.89–1.05, respectively. The accuracy expressed as percentage error and precision expressed as coefficient of variation were ≤±6 and ≤8%, respectively. The validated LC‐MS/MS method was applied to the measurement of triapine in patient samples from a phase I clinical trial. Copyright © 2015 John Wiley & Sons, Ltd.
Metabolic profiles of dioscin in rats revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry
Authors: Zhu He , Xu Jin‐Di , Mao Qian , Shen Hong , Kong Ming , Chen Jian‐Ping , Li Song‐Lin 
Published: February 2015

AbstractDioscin (DIS), one of the most abundant bioactive steroidal saponins in Dioscorea sp., is used as a complementary medicine to treat coronary disease and angina pectoris in China. Although the pharmacological activities and pharmacokinetics of DIS have been well demonstrated, information regarding the final metabolic fates is very limited. This study investigated the in vivo metabolic profiles of DIS after oral administration by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry method. The structures of the metabolites were identified and tentatively characterized by means of comparing the molecular mass, retention time and fragmentation pattern of the analytes with those of the parent compound. A total of eight metabolites, including seven phase I and one phase II metabolites, were detected and tentatively identified for the first time. Oxidation, deglycosylation and glucuronidation were found to be the major metabolic processes of the compound in rats. In addition, a possible metabolic pathway on the biotransformation of DIS in vivo was proposed. This study provides valuable and new information on the metabolism of DIS, which will be helpful for further understanding its mechanism of action. Copyright © 2015 John Wiley & Sons, Ltd.
A simple high‐performance liquid chromatography for the determination of linezolid in human plasma and saliva
Authors: Hara Shuuji , Uchiyama Masanobu , Yoshinari Masami , Matsumoto Taichi , Jimi Shiro , Togawa Atsushi , Takata Tohru , Takamatsu Yasushi 
Published: February 2015

AbstractLinezolid is an antimicrobial agent for the treatment of multiresistant Gram‐positive infections. A practical high‐performance liquid chromatography method was developed for the determination of linezolid in human plasma and saliva. Linezolid and an internal standard (o‐ethoxybenzamide) were extracted from plasma and saliva with ethyl acetate and analyzed on a Capcell Pak C18 MG column with UV detection at 254 nm. The calibration curve was linear through the range 0.5–50 µg/mL using a 200 μL sample volume. The intra‐ and interday precisions were all <6.44% for plasma and 5.60% for saliva. The accuracies ranged from 98.8 to 110% for both matrices. The mean recoveries of linezolid were 80.8% for plasma and 79.0% for saliva. This method was used to determine the plasma and saliva concentrations of linezolid in healthy volunteers who were orally administered a 600 mg dose of linezolid. Our liquid–liquid extraction procedure is easy and requires a small volume of plasma or saliva (200 μL). This small volume can be advantageous in clinical pharmacokinetic studies, especially if children participate. Copyright © 2015 John Wiley & Sons, Ltd.
Cyclopentenone Derivatives and Polyhydroxylated Steroids from the Soft Coral Sinularia acuta
Authors: Zhang Nai‐Xia , Tang Xu‐Li , van Ofwegen Leen , Xue Lei , Song Wen‐Juan , Li Ping‐Lin , Li Guo‐Qiang 
Published: February 2015

AbstractFour new polyhydroxylated steroids, 1–4, and the racemic form of cyclopentenone 9, together with four known steroids, 5–8, one known cyclopentenone derivative, 10, and one known butenolide derivative, 11, were isolated from the soft coral Sinularia acuta collected from Weizhou Island of Guangxi Province, P. R. China. Their structures were elucidated on the basis of spectroscopic analyses and by comparison of the corresponding data with those previously reported. The cytotoxicities of the isolates 1–11 in vitro against the selected tumor cell lines HL‐60, HeLa, and K562 were evaluated. Compounds 2 and 5 showed potent cytotoxicities against HL‐60 cell lines with IC50 values of 7.3 and 9.9 μM, respectively. Compounds 5 and 6 showed moderate activities against K562 cell lines with IC50 values of 10.9 and 11.7 μM, respectively, while compounds 1, 2, and 6 showed weak activities against HeLa cell lines with respective IC50 values of 44.8, 27.1, and 18.2 μM. This is the first report on chemical and bioactivity research of S. acuta.