bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification, immobilization, and characterization of a specific lipase from Staphylococcus warneri EX17 by enzyme fractionating via adsorption on different hydrophobic supports
Authors: Volpato Giandra , Filice Marco , de las Rivas Blanca , Rodrigues Rafael C. , Heck Júlio X. , Fernandez‐Lafuente Roberto , Guisan Jose M. , Mateo Cesar , Ayub Marco Antônio Záchia 
Published: March 2011

AbstractStaphylococcus warneri strain EX17 produces three lipases with different molecular weights of 28, 30, and 45 kDa. The 45 kDa fraction (SWL‐45) has been purified from crude protein extracts by one chromatographic step based on the selective adsorption of this lipase by interfacial activation on different hydrophobic supports at low ionic strength. The adsorption of SWL‐45 on octyl‐Sepharose increased the enzyme activity by 60%, but the other lipases were also adsorbed on this support. Using butyl‐Toyopearl, which is a lesser hydrophobic support, the purification factor was close to 20, and the only protein band detected on the sodium dodecyl sulfate‐polyacrylamide electrophoresis analysis gel was that corresponding to the SWL‐45, which could be easily desorbed from the support by incubation with triton X‐100, producing a purified enzyme. SWL‐45 was immobilized under very mild conditions on cyanogen bromide Sepharose, showing similar activities and stability as for its soluble form but without intermolecular interaction. The effects of different detergents over the activity of the immobilized SWL‐45 were analyzed, which was hyperactivated by factors of 1.3 and 2.5 with 0.01% Tween 80 and 0.1% Triton X‐100, respectively, while ionic detergents produced detrimental effects on the enzyme activity even at very low concentrations. Optimal reaction conditions and the effect of other additives on the enzyme activity were also investigated. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Kinetic characterization of the group II helicoverpa armigera nucleopolyhedrovirus propagated in suspension cell cultures: Implications for development of a biopesticides production process
Authors: Pedrini Márcia R. S. , Reid Steven , Nielsen Lars K. , Chan Leslie C. L. 
Published: March 2011

AbstractLarge‐scale commercialization of baculovirus biopesticides for the control of insect pests requires a cell culture production process, and knowledge of the infection kinetics is a vital prerequisite for process optimization. Well‐characterized kinetic parameters have so far only been reported for the commercially established recombinant Autographa californica nucleopolyhedrovirus (AcMNPV), a Group I NPV. In this work, key infection kinetic parameters of the Group II NPV Helicoverpa armigera nucleopolyhedrovirus (HaSNPV), and its Few Polyhedra (FP) mutant, were well characterized for the first time, in suspension HzAM1 insect cell cultures, to facilitate the scale‐up of an HaSNPV‐based biopesticide. The FP mutant had a selective advantage over wild‐type HaSNPV in cell cultures, and the kinetic analysis showed that this was due to a superior budding rate, rather than a faster binding rate (BR) or longer budding duration. Another finding was that wild‐type HaSNPV had very poor infection kinetics when compared with AcMNPV, exhibiting an 18‐fold lower BR, a more than 50‐fold lower budding rate, and a 60‐fold lower extracellular/total progeny virus ratio. Such poor infection kinetics have serious implications during scale‐up of an HaSNPV biopesticide production process, including the requirement for large volumes of virus inocula and the difficulty of achieving synchronous infections. Groups I and II NPVs may have very different infection kinetics because of their different envelope fusion proteins. This study is the first to compare the two groups of NPVs in terms of well‐characterized cell‐specific infection kinetics, and the findings may indicate a phylogenetic basis for kinetic differences. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Caught in the Act: Visualization of SNARE‐Mediated Fusion Events in Molecular Detail
Authors: Risselada Herre Jelger , Kutzner Carsten , Grubmüller Helmut 
Published: March 2011

AbstractNeurotransmitter release at the synapse requires fusion of synaptic vesicles with the presynaptic plasma membrane. SNAREs are the core constituents of the protein machinery responsible for this membrane fusion, but the actual fusion mechanism remains unclear. Here, we have simulated neuronal SNARE‐mediated membrane fusion in molecular detail. In our simulations, membrane fusion progresses through an inverted micelle fusion intermediate before reaching the hemifused state. We show that at least one single SNARE complex is required for fusion, as has also been confirmed in a recent in vitro single‐molecule fluoresence study. Further, the transmembrane regions of the SNAREs were found to play a vital role in the initiation of fusion by causing distortions of the lipid packing of the outer membrane leaflets, and the C termini of the transmembrane regions are associated with the formation of the fusion pores. The inherent mechanical stress in the linker region of the SNARE complex was found to drive both the subsequent formation and expansion of fusion pores. Our simulations also revealed that the presence of homodimerizations between the transmembrane regions leads to the formation of unstable fusion intermediates that are under high curvature stress. We show that multiple SNARE complexes mediate membrane fusion in a cooperative and synchronized process. Finally, we show that after fusion, the zipping of the SNAREs extends into the membrane region, in agreement with the recently resolved X‐ray structure of the fully assembled state.
Electronic Effects in the Catalytic Hydrosilylation with In‐Situ Generated Iron(II)‐Catalysts
Authors: Muller Keven , Schubert Anett , Jozak Thomas , Ahrens‐Botzong Annegret , Schünemann Volker , Thiel Werner R. 
Published: March 2011

AbstractIn combination with different aromatic N,N‐donors, iron acetate and octanoate are suitable catalyst precursors for the hydrosilylation of carbonyl compounds. Iron octanoate can be used to perform this catalytic transformation in cheap and non‐toxic petrol ether or heptane as the solvent and with versatile polymethylhydrosiloxane (PMHS) as the silane source. Investigation of the preformed catalyst (iron octanoate+N,N‐ligand+PMHS) by using Mössbauer spectroscopy suggests that the active species is a high‐spin iron(II) system.
Selective Synthesis of Fe7Se8 Polyhedra with Exposed High‐Index Facets and Fe7Se8 Nanorods by a Solvothermal Process in a Binary Solution and Their Collective Intrinsic Properties
Authors: Gao Min‐Rui , Lin Zhao‐Yang , Jiang Jun , Yao Hong‐Bin , Lu Yong‐Ming , Gao Qiang , Yao Wei‐Tang , Yu Shu‐Hong 
Published: March 2011

AbstractFe7Se8 polyhedra with high‐index facets and Fe7Se8 nanorods can be selectively synthesized by a solvothermal reaction in a mixed solvent of diethylenetriamine (DETA) and deionized water (DIW). It is found that the morphologies of Fe7Se8 nanocrystals can be effectively controlled by adjusting the volume ratio of DETA and DIW. The unusual polyhedral crystals are bounded by two {001} and twelve {012} facets. The intrinsic properties of Fe7Se8 nanocrystals have been investigated. Magnetic measurements indicate that the obtained polyhedra and nanorods show a weak ferromagnetic ordering at room temperature. In particular, a new photoluminescence emission at 403 nm from the Fe7Se8 nanocrystals has been observed. The described solvothermal reaction in a mixed solvent may be extended to the synthesis of other transition‐metal chalcogenide crystals with controlled shape, facets, and structure, which may bring new functionalities.
Enhancing Gas Adsorption and Separation Capacity through Ligand Functionalization of Microporous Metal–Organic Framework Structures
Authors: Zhao Yonggang , Wu Haohan , Emge Thomas J. , Gong Qihan , Nijem Nour , Chabal Yves J. , Kong Lingzhu , Langreth David C. , Liu Hui , Zeng Heping , Li Jing 
Published: March 2011

AbstractHydroxyl‐ and amino‐ functionalized [Zn(BDC)(TED)0.5]⋅2DMF⋅0.2H2O leads to two new structures, [Zn(BDC‐OH)(TED)0.5]⋅1.5DMF⋅0.3H2O and [Zn(BDC‐NH2)(TED)0.5]⋅xDMF⋅yH2O (BDC=terephthalic acid, TED=triethylenediamine, BDC‐OH=2‐hydroxylterephthalic acid, BDC‐NH2=2‐aminoterephthalic acid). Single‐crystal X‐ray diffraction and powder X‐ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)0.5]⋅2DMF⋅0.2H2O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC‐OH)(TED)0.5]⋅1.5DMF⋅0.3H2O and [Zn(BDC‐NH2)(TED)0.5]⋅xDMF⋅yH2O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH2 groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)0.5]⋅2DMF⋅0.2H2O takes up the highest amount of H2 at low temperatures. Interestingly, however, both [Zn (BDC‐OH)(TED)0.5]⋅1.5DMF⋅0.3H2O and [Zn(BDC‐NH2)(TED)0.5] ⋅xDMF⋅yH2O show significant enhancement in CO2 uptake at room temperature, suggesting that the strong interactions between CO2 and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO2 adsorption. A comparison of single‐component CO2, CH4, CO, N2, and O2 adsorption isotherms demonstrates that the adsorption selectivity of CO2 over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO2 and H2 adsorption potentials.
Immobilization of DNA on Magnetic Microparticles for Mercury Enrichment and Detection with Flow Cytometry
Authors: Huang Po‐Jung Jimmy , Liu Juewen 
Published: March 2011

AbstractMercury detection in water has attracted a lot of research interest due to its highly toxic nature and adverse environmental impact. In particular, the recent discovery of specific binding of HgII to thymine‐rich (T‐rich) DNA resulting in T‐HgII‐T base pairs has led to the development of a number of sensors with different signaling mechanisms. However, the majority of such sensors were non‐immobilized. Immobilization, on the other hand, allows active mercury adsorption, signal amplification, and sensor regeneration. In this work, we immobilized a thymine‐rich DNA on a magnetic microparticle (MMP) surface through biotin–streptavidin interactions. In the presence of HgII, the DNA changes from a random coil structure into a hairpin, upon which SYBR Green I binds to emit green fluorescence. Detection was carried out by using flow cytometry where the fluorescence intensity increased ≈9‐fold in the presence of mercury and the binding of mercury reached equilibrium in less than 2 min. The sensor showed a unique sample‐volume‐dependent fluorescence signal change where a higher fluorescence was obtained with a larger sample volume, suggesting that the particles can actively adsorb HgII. Detection limits of 5 nM (1 ppb) and 14 nM (2.8 ppb) were achieved in pure buffer and in mercury‐spiked Lake Ontario water samples, respectively.
Green and Blue Electrochemically Generated Chemiluminescence from Click Chemistry—Customizable Iridium Complexes
Authors: Zanarini Simone , Felici Marco , Valenti Giovanni , Marcaccio Massimo , Prodi Luca , Bonacchi Sara , Contreras‐Carballada Pablo , Williams Rene M. , Feiters Martin C. , Nolte Roeland J. M. , De Cola Luisa , Paolucci Francesco 
Published: March 2011

AbstractCationic cyclometalated iridium complexes containing two anionic phenylpyridine (ppy) ligands and the neutral bidentate triazole–pyridine ligand, 2‐(1‐substituted‐1H‐1,2,3‐triazol‐4‐yl)pyridine (pytl), were investigated. The complexes display a rich and reversible electrochemical behavior, upon investigations by cyclic voltammetry in strictly aprotic conditions, that couples with excellent emission quantum yields and long lifetimes of the excited states. Therefore, in organic media, all complexes have generated intense green electrochemiluminescence (ECL) through the so‐called annihilation procedure and, importantly, a modulation of the emission energy (to blue) has been easily obtained by simple fluorination of the ppy ligand. Finally, taking advantage of their remarkable solubility in water, intense ECL was also obtained from aqueous buffer solutions using the co‐reactant method, thus making all the investigated complexes highly promising for their effective use as ECL labels in bioanalytical applications.
Quantum Chemical Studies of the Hydration of Sr2+ in Vacuum and Aqueous Solution
Authors: Kerridge Andrew , Kaltsoyannis Nikolas 
Published: March 2011

AbstractThe geometric structures of gas‐phase Sr2+ hydrates are calculated quantum chemically by using hybrid (B3LYP) and meta‐GGA (TPSS) density functional theory, and a range of thermodynamic data (including sequential bond enthalpies, entropies and free energies for the reactions Sr2+(H2O)n−1+H2O→Sr2+(H2O)n) are shown to be in excellent agreement with experiment. When the number of coordinating water molecules exceeds six, such that water begins to occupy the second solvation shell, it is found that detailed analysis based on both geometrical and conformational entropy is required in order to confidently identify the experimentally observed structures. The significant increase in coordination number observed experimentally between the gas‐ and aqueous‐phase species is successfully reproduced, as is the first solvation shell geometry. Inaccurate second shell geometries imply that larger model systems may be required to achieve agreement with experiment. Candidate species for on‐going computational studies of the interaction of hydrated Sr2+ with brucite surfaces have been identified.
Relationship between Channel and Sorption Properties in Coordination Polymers with Interdigitated Structures
Authors: Hijikata Yuh , Horike Satoshi , Sugimoto Masayuki , Sato Hiroshi , Matsuda Ryotaro , Kitagawa Susumu 
Published: March 2011

AbstractPorous coordination polymers constructed from Zn2+ and isophthalate with linear bipyridyl‐type ligands were synthesized. [Zn(ip)(bpb)]n (CID‐21; ip=isophthalate, bpb=1,4‐bis(4‐pyridyl)benzene), [Zn(ip)(bpt)]n (CID‐22; bpt=3,6‐bis(4‐pyridyl)‐1,2,4,5‐tetrazine), and [Zn(ip)(bpa)]n (CID‐23; bpa=1,4‐bis(4‐pyridyl)acetylene) all have interdigitated structures of layers and similar void volumes (≈27 %). In these compounds, 1D bottleneck‐type channels run along the perpendicular direction of the layer stacking and their properties are strongly dominated by the dipyridyl linker ligands. Because of the difference in packing of 2D layers, CID‐21 and CID‐22 have relatively rigid porous structures, whereas CID‐23 has greater flexibility, as indicated by the results of powder X‐ray diffraction studies. The micropores of CID‐22 surrounded by tetrazine moieties adsorb polar molecules, such as methanol and water. The higher affinity of CID‐22 for water than CID‐21 is supported by a theoretical study. The 1D channel of CID‐23 is wider than that of the other two compounds, which enables the incorporation of aromatic molecules. This is because the shape of the bpa linker ligand generates a wider pore diameter (8.6 Å). Only CID‐23 can adsorb a benzene molecule and the isotherm of benzene has a gate‐opening‐type profile. This offers proof of the guest accommodation process through large structural transformation from a nonporous to a porous structure. The flexibility and restricted pore space of CID‐23, at 298 K, allows only benzene, but not cyclohexane, to enter the channels. The porous structure exhibits clear selectivity for these similar guests. The incorporation of an elongated dipyridyl linker ligand in the 2D coordination layers provides a strategy for the design of microporous compounds with different flexibilities, microporous environments, and separation abilities.
Towards the Limit of Atropochiral Stability: H‐MIOP, an N‐Heterocyclic Carbene Precursor and Cationic Analogue of the H‐MOP Ligand
Authors: Abdellah Ibrahim , Boggio‐Pasqua Martial , Canac Yves , Lepetit Christine , Duhayon Carine , Chauvin Remi 
Published: March 2011

AbstractThe configurational stability of biaryl motifs is addressed for the 1‐naphthyl‐N‐benzimidazolyl motif substituted by a single diphenylphosphinyl group at the 2‐position. The atropoenantiomers of the N‐methylated cation H‐MIOP, a less sterically locked analogue of the neutral H‐MOP ligand, were resolved by enantiospecific cleavage of the N2CP bond of the resolved enantiomers of BIMIONAP. The latter were obtained by enantiospecific N‐methylation of the previously resolved enantiomers of neutral BIMINAP. PdCl2 complexes of the P,C‐chelating N‐heterocyclic carbene (NHC)–phosphine ligands derived from (R)‐ and (S)‐H‐MIOP were prepared by two enantiospecific routes: by N2CP bond cleavage from the (R)‐ and (S)‐BIMIONAP–PdCl2 complexes, or by simultaneous coordination of the P and C atoms of the in situ generated free NHC–phosphine. The enantiomerization pathways of H‐MOP, H‐MIOP, and corresponding NHC–phosphine have been investigated at the B3PW91/6‐31G(d,p) level of theory. The calculated enantiomerization barriers of H‐MOP and H‐MIOP in acetonitrile are equal to 176.0 and 146.4 kJ mol−1, respectively, and are mainly determined by the distortion of the naphthalene and/or benzimidazole motifs in the transition state. Beyond the stability of their optical rotation at room temperature, the respective calculated Oki’s racemization temperatures of 334 and 225 °C allowed us to consider both ligands as configurationally stable.
Natural pericosines B and C as enantiomeric mixtures: Direct evidence by chiral HPLC analysis
Authors: Usami Yoshihide , Okada Yusuke , Yamada Takeshi 
Published: March 2011

AbstractPericosines are carbasugar‐type metabolites of Periconia byssoides OUPS‐N133, a fungus that was originally separated from the sea hare Aplysia kurodai. It has been reported that pericosines C and E are enantiomeric mixtures. The difference in specific rotation between natural pericosine C and the synthetic one led to the conclusion that natural pericosine C is an enantiomeric mixture. Meanwhile, the small specific rotation of natural pericosine B compared to that of the synthetic one led to the deduction that natural pericosine B might also be an enantiomeric mixture. Then, racemic pericosines B and C were synthesized, and the direct enantioseparation of these racemic carbasugars was conducted with CHIRALPAK® IA and CHIRALPAK® AY‐H, which are suitable columns for racemic pericosines B and C, respectively. Using chiral HPLC, we conclude that natural pericosines B and C exist as enantiomeric mixtures. A rare example of the application of direct chiral HPLC analysis to intact sugars or carbasugars was provided. Chirality 2011. © 2011 Wiley Periodicals, Inc.
Comparative study on kynurenic acid production in the rat striatum by tryptophan enantiomers: An in vivo microdialysis study
Authors: Ishii Kana , Iizuka Hideaki , Ogaya Tadahiro , Song Ziyu , Fukushima Takeshi 
Published: March 2011

AbstractKynurenic acid (KYNA), an endogenous antagonist of N‐methyl‐D‐aspartate and α7 nicotinic acetylcholine receptors, is one of the L‐tryptophan (Trp) metabolites. To compare the level of KYNA produced in the striatum of rats after independent administration of L‐Trp and D‐Trp, rats were intraperitoneally administered L‐Trp and/or D‐Trp (100 mg/kg), and a microdialysis (MD) probe was implanted in the striatum. The KYNA level in the MD samples was determined using the column‐switching high‐performance liquid chromatography system. KYNA levels in the MD samples increased by approximately twofold in rats that were administered D‐Trp or L‐Trp; this result suggests that just as L‐Trp, D‐Trp was also metabolized to KYNA in the striatum. Additionally, 30 min before the administration of D‐Trp, rats were administered 3‐methyl pyrazole‐5‐carboxylic acid (MPC) (50 mg/kg), which is a specific inhibitor of D‐amino acid oxidase (DAAO). Pretreatment with MPC suppressed striatal KYNA production; this result suggests that DAAO, encoded by one of the susceptible genes for schizophrenia, may contribute to the production of KYNA from D‐Trp in the striatum of rats. Chirality 2011. © 2011 Wiley Periodicals, Inc.
Calcium Channel Blocker Inhibition of AGE and RAGE Axis Limits Renal Injury in Nondiabetic Patients With Stage I or II Chronic Kidney Disease
Authors: Nakamura Tsukasa , Sato Eiichi , Fujiwara Nobuharu , Kawagoe Yasuhiro , Koide Hikaru , Ueda Yoshihiko , Takeuchi Masayoshi , Yamagishi Sho‐ichi 
Published: March 2011

AbstractBackground:There is a growing body of evidence that advanced glycation end products (AGE) and their receptor (RAGE) system are implicated in chronic kidney disease (CKD). We have previously found that a long‐acting calcium channel blocker, azelnidipine, but not amlodipine, improves renal injury in CKD patients. However, little is known about the effect of azelnidipine on the AGE‐RAGE axis in humans. In this study, we examined whether azelnidipine addition could have renoprotective properties in hypertensive CKD patients by reducing serum levels of AGE and soluble form of RAGE (sRAGE). Thirty nondiabetic stage I or II CKD patients who had already been treated with angiotensin II receptor blockers were enrolled in this study.Hypothesis:We hypothesized that azelnidipine treatment could limit renal injury partly by blocking the AGE‐RAGE axis.Methods:Patients were randomly divided into 2 groups; one group was treated with 16 mg azelnidipine and the other with 5 mg amlodipine once daily. They were followed up for 6 months.Results:Proteinuria was positively correlated with circulating AGE and sRAGE levels in our subjects. Both drugs exhibited comparable and significant blood pressure (BP)‐lowering effects. Although neither of them affected glucose, glycated hemoglobin, lipid levels, and estimated glomerular filtration rate, treatment with azelnidipine, but not amlodipine, decreased circulating AGE, sRAGE, proteinuria, and urinary levels of liver‐type fatty acid binding protein, a marker of tubular injury, in a BP‐lowering–independent manner.Conclusions:Our present results suggest that azelnidipine may exert renoprotective properties in nondiabetic hypertensive CKD patients via its unique inhibitory effects on the AGE‐RAGE axis. © 2011 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Extracting date/time expressions in super‐function based Japanese–English machine translation
Authors: Sasayama Manabu , Kuroiwa Shingo , Ren Fuji 
Published: March 2011

AbstractSuper‐function based machine translation (SFBMT), which is a type of example‐based machine translation, has a feature which makes it possible to expand the coverage of examples by changing nouns into variables. However, there have been problems extracting entire date/time expressions containing parts‐of‐speech other than nouns, because only nouns/numbers were changed into variables. We describe a method of extracting date/time expressions for SFBMT. SFBMT uses noun determination rules to extract nouns and a bilingual dictionary to obtain the correspondence of the extracted nouns between the source and the target languages. In this method, we add a rule to extract date/time expressions and then extract date/time expressions from a Japanese–English bilingual corpus. The evaluation results shows that the precision of this method for Japanese sentences is 96.7%, with a recall of 98.2%, and the precision for English sentences is 94.7%, with a recall of 92.7%. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(4): 44–54, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10262