bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Energetics of a Three‐State Protein Folding System Probed by High‐Pressure Relaxation Dispersion NMR Spectroscopy
Authors: Tugarinov Vitali , Libich David S. , Meyer Virginia , Roche Julien , Clore G. Marius 
Published: August 2015

AbstractThe energetic and volumetric properties of a three‐state protein folding system, comprising a metastable triple mutant of the Fyn SH3 domain, have been investigated using pressure‐dependent 15N‐relaxation dispersion NMR from 1 to 2500 bar. Changes in partial molar volumes (ΔV) and isothermal compressibilities (ΔκT) between all the states along the folding pathway have been determined to reasonable accuracy. The partial volume and isothermal compressibility of the folded state are 100 mL mol−1 and 40 μL mol−1 bar−1, respectively, higher than those of the unfolded ensemble. Of particular interest are the findings related to the energetic and volumetric properties of the on‐pathway folding intermediate. While the latter is energetically close to the unfolded state, its volumetric properties are similar to those of the folded protein. The compressibility of the intermediate is larger than that of the folded state reflecting the less rigid nature of the former relative to the latter.
Synthesis of Well‐Defined Bicapped Octahedral Iron Clusters [(trenL)2Fe8(PMe2Ph)2]n (n=0, −1)
Authors: Sánchez Raúl Hernández , Willis Alexander M. , Zheng Shao‐Liang , Betley Theodore A. 
Published: August 2015

AbstractThe synthesis of polynuclear clusters with control over size and cluster geometry remains an unsolved challenge. Herein, we report the synthesis and characterization of open‐shell octairon clusters supported by two heptaamine ligands [o‐H2NC6H4NH(CH2)2]3N (trenLH9). The crystal structure of the all‐ferrous species ([trenL)2Fe8(PMe2Ph)2] (1) displays a bicapped octahedral geometry with FeFe distances ranging from 2.4071(6) to 2.8236(5) Å, where the ligand amine units are formally in amine, amide, and imide oxidation states. Several redox states of the octairon cluster are accessible, as ascertained using cyclic voltammetry. The one‐electron‐reduced clusters [M]+[(trenL)2Fe8(PMe2Ph)2]− (M=Bu4N (2 a); (15‐crown‐5)Na(thf) (2 b)) were isolated and characterized. Variable‐temperature magnetic susceptibility data indicates that the exchange coupling within the [Fe8] core is antiferromagnetic which is attenuated upon reduction to the mixed valent anion.
Synthesis of Silicate Zeolite Analogues Using Organic Sulfonium Compounds as Structure‐Directing Agents
Authors: Jo Changbum , Lee Sungjune , Cho Sung June , Ryoo Ryong 
Published: August 2015

AbstractA microporous crystalline silica zeolite of the MEL structure type and three other zeolite analogues composed of germanosilicate frameworks were synthesized using tributylsulfonium, triphenylsulfonium, or tri(para‐tolyl)sulfonium as the structure‐directing agent. The germanosilicates thus obtained had ISV, ITT, or a new zeolite structure depending on the synthesis conditions. The structure of the new germanosilicate was solved using X‐ray powder diffraction data with the aid of a charge‐flipping method. The solution indicated a crystal structure belonging to the P63/mmc space group with cell parameters of a=16.2003 Å and c=21.8579 Å. After calcination, the new germanosilicate material exhibited two types of accessible micropores with diameters of 0.61 and 0.78 nm.
Time‐Resolved Crystallography of the Reaction Intermediate of Nitrile Hydratase: Revealing a Role for the Cysteinesulfenic Acid Ligand as a Catalytic Nucleophile
Authors: Yamanaka Yasuaki , Kato Yuki , Hashimoto Koichi , Iida Keisuke , Nagasawa Kazuo , Nakayama Hiroshi , Dohmae Naoshi , Noguchi Keiichi , Noguchi Takumi , Yohda Masafumi , Odaka Masafumi 
Published: August 2015

AbstractThe reaction mechanism of nitrile hydratase (NHase) was investigated using time‐resolved crystallography of the mutant NHase, in which βArg56, strictly conserved and hydrogen bonded to the two post‐translationally oxidized cysteine ligands, was replaced by lysine, and pivalonitrile was the substrate. The crystal structures of the reaction intermediates were determined at high resolution (1.2–1.3 Å). In combination with FTIR analyses of NHase following hydration in H218O, we propose that the metal‐coordinated substrate is nucleophilically attacked by the O(SO−) atom of αCys114‐SO−, followed by nucleophilic attack of the S(SO−) atom by a βArg56‐activated water molecule to release the product amide and regenerate αCys114‐SO−.
An Inexpensive and Recyclable Silver‐Foil Catalyst for the Cyclopropanation of Alkenes with Diazoacetates under Mechanochemical Conditions
Authors: Chen Longrui , Bovee Mark O. , Lemma Betsegaw E. , Keithley Kimberlee S. M. , Pilson Sara L. , Coleman Michael G. , Mack James 
Published: August 2015

AbstractThe diastereoselective cyclopropanation of various alkenes with diazoacetate derivatives can be achieved under mechanochemical conditions using metallic silver foil and a stainless‐steel vial and ball system. This solvent‐free method displays analogous reactivity and selectivity to solution‐phase reactions without the need for slow diazoacetate addition or an inert atmosphere. The heterogeneous silver‐foil catalyst system is easily recyclable without any appreciable loss of activity or selectivity being observed. The cyclopropanation products were obtained with excellent diastereoselectivities (up to 98:2 d.r.) and in high yields (up to 96 %).
Chiral Polymers of Intrinsic Microporosity: Selective Membrane Permeation of Enantiomers
Authors: Weng Xilun , Baez José E. , Khiterer Mariya , Hoe Madelene Y. , Bao Zongbi , Shea Kenneth J. 
Published: August 2015

AbstractFollowing its resolution by diastereomeric complexation, 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane (TTSBI) was used to synthesize a chiral ladder polymer, (+)‐PIM‐CN. (+)‐PIM‐COOH was also synthesized by the acid hydrolysis of (+)‐PIM‐CN. Following characterization, both (+)‐PIM‐CN and (+)‐PIM‐COOH were solvent cast directly into semipermeable membranes and evaluated for their ability to enable the selective permeation of a range of racemates, including mandelic acid (Man), Fmoc‐phenylalanine, 1,1′‐bi‐2‐naphthol (binol), and TTSBI. High ee values were observed for a number of analytes, and both materials exhibited high permeation rates. A selective diffusion–permeation mechanism was consistent with the results obtained with these materials. Their high permeability, processability, and ease of chemical modification offer considerable potential for liquid‐phase membrane separations and related separation applications.
A Metal‐Free Synthesis of N‐Aryl Carbamates under Ambient Conditions
Authors: Guo Wusheng , Gónzalez‐Fabra Joan , Bandeira Nuno A. G. , Bo Carles , Kleij Arjan W. 
Published: August 2015

AbstractThe first chemo‐ and site‐selective process for the formation of N‐aryl‐carbamates from cyclic organic carbonates and aromatic amines is reported. The reactions proceed smoothly under extremely mild reaction conditions using TBD (triazabicyclodecene) as an effective and cheap organocatalyst, thus providing a sustainable and new methodology for the formation of a wide variety of useful N‐aryl carbamate synthons in good to excellent yields. Computational investigations have been performed and show the underlying reason for the observed unique reactivity as related to an effective proton‐relay mechanism mediated by the bicyclic guanidine base.
Chlorine‐Free Red‐Burning Pyrotechnics
Authors: Sabatini Jesse J. , Koch Ernst‐Christian , Poret Jay C. , Moretti Jared D. , Harbol Seth M. 
Published: August 2015

AbstractThe development of a red, chlorine‐free pyrotechnic illuminant of high luminosity and spectral purity was investigated. Red‐light emission based solely on transient SrOH(g) has been achieved by using either 5‐amino‐1H‐tetrazole or hexamine to deoxidize the combustion flame of a Mg/Sr(NO3)2/Epon‐binder composition and reduce the amount of both condensed and gaseous SrO, which emits undesirable orange‐red light. The new formulations were found to possess high thermal onset temperatures. Avoiding chlorine in these formulations eliminates the risk of the formation of PCBs, PCDDs, and PCDFs. This finding, hence, will have a great impact on both military pyrotechnics and commercial firework sectors.
Promotion of Inflammatory Arthritis by Interferon Regulatory Factor 5 in a Mouse Model
Authors: Duffau Pierre , Menn‐Josephy Hanni , Cuda Carla M. , Dominguez Salina , Aprahamian Tamar R. , Watkins Amanda A. , Yasuda Kei , Monach Paul , Lafyatis Robert , Rice Lisa M. , Kenneth Haines G. , Gravallese Ellen M. , Baum Rebecca , Richez Christophe , Perlman Harris , Bonegio Ramon G. , Rifkin Ian R. 
Published: August 2015

ObjectivePolymorphisms in the transcription factor interferon regulatory factor 5 (IRF5) are associated with an increased risk of developing rheumatoid arthritis (RA). This study was undertaken to determine the role of IRF5 in a mouse model of arthritis development.MethodsK/BxN serum–transfer arthritis was induced in mice deficient in IRF5, or lacking IRF5 only in myeloid cells, and arthritis severity was evaluated. K/BxN arthritis was also induced in mice deficient in TRIF, Toll‐like receptor 2 (TLR2), TLR3, TLR4, and TLR7 to determine the pathways through which IRF5 might promote arthritis. In vitro studies were performed to determine the role of IRF5 in interleukin‐1 (IL‐1) receptor and TLR signaling.ResultsArthritis severity was reduced in IRF5‐deficient, TRIF‐deficient, TLR3‐deficient, and TLR7‐deficient mice. The expression of multiple genes regulating neutrophil recruitment or function and bioactive IL‐1β formation was reduced in the joints during active arthritis in IRF5‐deficient mice. In vitro studies showed that TLR7 and the TRIF‐dependent TLR3 pathway induce proinflammatory cytokine production in disease‐relevant cell types in an IRF5‐dependent manner.ConclusionOur findings indicate that IRF5 contributes to disease pathogenesis in inflammatory arthritis. This is likely due at least in part to the role of IRF5 in mediating proinflammatory cytokine production downstream of TLR7 and TLR3. Since TLR7 and TLR3 are both RNA‐sensing TLRs, this suggests that endogenous RNA ligands present in the inflamed joint promote arthritis development. These findings may be relevant to human RA, since RNA capable of activating TLR7 and TLR3 is present in synovial fluid and TLR7 and TLR3 are up‐regulated in the joints of RA patients.
Juvenile Idiopathic Arthritis in Olmsted County, Minnesota, 1960–2013
Authors: Krause Megan L. , Crowson Cynthia S. , Michet C. John , Mason Thomas , Muskardin Theresa Wampler , Matteson Eric L. 
Published: August 2015

ObjectiveTo evaluate the incidence and prevalence of juvenile idiopathic arthritis (JIA) in Olmsted County, Minnesota in 1994–2013 and trends in juvenile rheumatoid arthritis (JRA) in 1960–2013.MethodsCases of arthritis in 1994–2013 were identified by diagnosis code with medical chart review to confirm diagnosis separately for JIA and JRA. Overall incidence rates with 95% confidence intervals (95% CIs) were age and sex adjusted to the 2010 US white population. Comparisons were made with an earlier (1960–1993) cohort from this same population.ResultsSeventy‐one incident cases of JIA in 1994–2013 were identified, with an overall age‐ and sex‐adjusted incidence rate of 10.3 per 100,000 (95% CI 7.9–12.7). Forty‐two (59%) were female, with an incidence of 12.4 per 100,000 (95% CI 8.6–16.2), as compared to 8.3 per 100,000 (95% CI 5.2–11.3) in males. The most common subtype was oligoarthritis (63%). The mean ± SD age at diagnosis was 8.2 ± 5.3 years. The prevalence of JIA on January 1, 2000 and January 1, 2010 was 51.0 per 100,000 (95% CI 25.2–76.8) and 57.6 per 100,000 (95% CI 31.0–94.5), respectively. When the annual incidence of JRA was compared over time from 1960 to 2013, there was no significant change in incidence overall; however, the incidence decreased among females (P = 0.003). A cyclic pattern of incidence was observed, with peaks approximately every 10 years. Similar to the findings with regard to incidence, prevalence did not change overall, but decreased among females (P = 0.048). There were 4 deaths in the cohort of JRA patients diagnosed in 1960–2013; the standardized mortality ratio was 1.50 (95% CI 0.41–3.83).ConclusionIncidence of juvenile arthritis overall in Olmsted County, Minnesota has not changed significantly in the past 53 years. A consistent cyclic pattern was noted.
Association of Polymorphisms of Cytochrome P450 2D6 With Blood Hydroxychloroquine Levels in Patients With Systemic Lupus Erythematosus
Authors: Lee Ji Yeon , Vinayagamoorthy Nadimuthu , Han Kyungdo , Kwok Seung Ki , Ju Ji Hyeon , Park Kyung Su , Jung Seung‐Hyun , Park Sung‐Won , Chung Yeun‐Jun , Park Sung‐Hwan 
Published: August 2015

ObjectiveTo evaluate associations of genetic polymorphisms in cytochrome P450 (CYP) isoforms 2D6, 3A5, and 3A4 with blood concentrations of hydroxychloroquine (HCQ) and its metabolite, N‐desethyl HCQ (DHCQ), in patients with systemic lupus erythematosus (SLE).MethodsSLE patients taking HCQ for >3 months were recruited and were genotyped for 4 single‐nucleotide polymorphisms in CYP2D6*10, CYP3A5*3, and CYP3A4*18B. Blood HCQ and DHCQ concentrations ([HCQ] and [DHCQ]) were measured and their association with corresponding genotypes was investigated.ResultsA total of 194 patients were included in the analysis. CYP2D6*10 polymorphisms (rs1065852 and rs1135840) were significantly associated with the [DHCQ]:[HCQ] ratio after adjustment for age, sex, dose per weight per day, and SLE Disease Activity Index score (P = 0.03 and P < 0.01, respectively). In adjusted models, the [DHCQ]:[HCQ] ratio was highest in patients with the G/G genotype of the CYP2D6*10 (rs1065852) polymorphism and lowest in those with the A/A genotype (P = 0.03). Similarly, the [DHCQ]:[HCQ] ratio was highest in patients with the C/C genotype of the CYP2D6*10 (rs1135840) polymorphism and lowest in those with the G/G genotype (P < 0.01). The CYP2D6*10 (rs1065852) polymorphism was significantly related to the [DHCQ] (P = 0.01). However, the polymorphisms of CYP3A5*3 and CYP3A4*18B did not show any significant association with the [HCQ], [DHCQ], or [DHCQ]:[HCQ] ratio.ConclusionOur study showed that the [DHCQ]:[HCQ] ratio was related to CYP2D6 polymorphisms in Korean lupus patients taking oral HCQ. CYP polymorphisms may explain why there is wide variation in blood HCQ concentrations. The role of an individual's CYP polymorphisms should be considered when prescribing oral HCQ.
Synthesis of Uniform, Monodisperse, Sophorolipid Twisted Ribbons
Authors: Cuvier Anne‐Sophie , Babonneau Florence , Berton Jan , Stevens Christian V. , Fadda Giulia C. , Genois Isabelle , Le Griel Patrick , Péhau‐Arnaudet Gérard , Baccile Niki 
Published: August 2015

AbstractControl over size monodispersity in chiral self‐assembled systems is important for potential applications like templating, tissue engineering or enantioselective chromatography, just to cite a few examples. In this context, it was reported that the saturated form of sophorolipids (SL), a bioderived glycolipid, are able to form self‐assembled twisted ribbons in water at neutral pH. Here, we show the possibility to control their size dispersion, generally between 10 and 40 nm after synthesis to a value of 13.5±1.5 nm, by a simple dialysis step eliminating the excess of NaCl. We use transmission electron microscopy under cryogenic conditions (cryo‐TEM) combined with small angle neutron scattering (SANS) to characterize the ribbon dispersion both visually and statistically. Two negative controls show the importance of salt in the aggregation process of the ribbons.
A Cyclodextrin‐Based Photoresponsive Molecular Gate that Functions Independently of Either Solvent or Potentially Competitive Guests
Authors: Loh Ka‐Heng , Smith Nicole M. , Onagi Hideki , Lincoln Stephen F. , Easton Christopher J. 
Published: August 2015

AbstractThe photoinduced interconversion between cinnamido‐substituted cyclodextrins constitutes a gating switch through which the substituent moves to open or block access to the cyclodextrin cavity. Most unusually for a cyclodextrin‐based device, the operation of this gate is solvent‐independent and unaffected by potentially competitive guests. It occurs in MeOH and DMSO, as well as in water. This contrasts with other cyclodextrin inclusion phenomena that are usually driven by hydrophobic effects and limited to aqueous media.
Quantitative analysis of histone H3 and H4 post‐translational modifications in doxorubicin‐resistant leukemia cells
Authors: Liu Tao , Guo Qingcheng , Guo Huaizu , Hou Sheng , Li Jing , Wang Hao 
Published: August 2015

AbstractThe epigenetic remodeling of chromatin through histone modifications has been widely implicated in drug resistance of cancer cells. However, whether epigenetic mechanisms contribute specifically to doxorubicin resistance in leukemia has not been carefully examined. Using a stable and sensitive workflow based on LC‐MS, we quantitatively compared the extents of methylation and acetylation of histone H3 and H4 in acute leukemia cell line HL60 and its doxorubicin‐resistant derivative, HL60/ADR, as well as the chronic leukemia cell line K562 and its doxorubicin‐resistant derivative, K562/ADR. We found that increased levels of H3K9 methylation, H3K14, H3K18 and H3K23 acetylation, and potentially H4K20 methylation, are associated with drug resistance in both cells. Our results demonstrated that the doxorubicin‐resistant acute and chronic leukemia cell lines may share a common epigenetic mechanism that involves a combination of transcriptional activation and silencing. Copyright © 2015 John Wiley & Sons, Ltd.
Protein Synthesis in Sub‐Micrometer Water‐in‐Oil Droplets
Authors: Gallo Valentina , Stano Pasquale , Luisi Pier Luigi 
Published: August 2015

AbstractWater‐in‐oil (w/o) emulsions are used as a cellular model because of their unique cell‐like architecture. Previous works showed the capability of eukaryotic‐cell‐sized w/o droplets (5–50 μm) to support protein synthesis efficiently; however data about smaller w/o compartments (<1 μm) are lacking. This work focuses on the biosynthesis of the enhanced green fluorescent protein (EGFP) inside sub‐micrometric lecithin‐based w/o droplets (0.8–1 μm) and on its dependence on the compartments’ dynamic properties in terms of solute exchange mechanisms. We demonstrated that protein synthesis is strongly affected by the nature of the lipid interface. These findings could be of value and interest for both basic and applied research.
A Mild and Chemoselective Reduction of Nitro and Azo Compounds Catalyzed by a Well‐Defined Mo3S4 Cluster Bearing Diamine Ligands
Authors: Pedrajas Elena , Sorribes Iván , Junge Kathrin , Beller Matthias , Llusar Rosa 
Published: August 2015

AbstractHerein, we report a novel well‐defined diamino Mo3S4‐based catalyst system for the reduction of nitroarenes and azo compounds to the corresponding anilines with silanes as reducing agents. This catalytic protocol provides a facile route to access aromatic amines under mild conditions in good to excellent yields. Notably, even anilines functionalized with other potentially reducible moieties are obtained with high selectivity. The new chemoselective catalyst of formula [Mo3S4Cl3(dmen)3](BF4) (dmen: N,N′‐dimethylethylenediamine) is conveniently synthesized through coordination of the diamine ligand to the incomplete Mo3S4 cubane‐type cluster core in a one‐pot two‐step procedure. The crystal structure of the [Mo3S4Cl3(dmen)3]+ cation confirms the formation of a single isomer in which the chlorine atom lies trans to the bridging sulfur atom to afford a C3 symmetry complex with intrinsic backbone chirality. The structure is preserved in solution, as evidenced by multinuclear NMR spectroscopy and electrospray‐ionization mass spectrometric techniques.
Structural Engineering of Electrocatalysts for the Hydrogen Evolution Reaction: Order or Disorder?
Authors: Xie Junfeng , Xie Yi 
Published: August 2015

AbstractElectrocatalytic hydrogen evolution has been regarded as a promising strategy to realize efficient hydrogen production to face the energy crisis in the future. Hence, the design of hydrogen‐evolving catalysts with high activity and low cost is imperative. In this Minireview article, state‐of‐the‐art electrocatalysts for the hydrogen evolution reaction (HER) are overviewed, and the strategies for constructing ordered and disordered HER electrocatalysts are summarized in detail. By means of facet engineering, nanoscale, polymorph engineering accompanied by interface engineering, HER catalysts with an ordered structure could be optimized. For designing disordered catalysts, defect engineering, amorphization, elemental doping, and surface modification, as well as constructingan alloyed structure, could be effective to realize the beneficial modulation of active sites and electronic structure. This Minireview provides a structural perspective for the design of efficient HER electrocatalysts in the future.
Cascade Coupling of Ene‐Reductases and ω‐Transaminases for the Stereoselective Synthesis of Diastereomerically Enriched Amines
Authors: Monti Daniela , Forchin Maria Chiara , Crotti Michele , Parmeggiani Fabio , Gatti Francesco G. , Brenna Elisabetta , Riva Sergio 
Published: August 2015

AbstractOne‐pot sequential and cascade processes performed by employing ene‐reductases (ERs) together with ω‐transaminases (ω‐TAs) for the obtainment of diastereomerically enriched (R)‐ and (S)‐amine derivatives containing an additional stereocenter were investigated. By using either α‐ or β‐substituted unsaturated ketones as substrates and by coupling purified ERs belonging to the Old Yellow Enzyme (OYE) family with a panel of commercially available ω‐TAs, the desired products were obtained in up to >99 % conversion and >99 % de. The sequential reactions were performed in a one‐pot fashion with no need to adapt the reaction conditions to the reductive amination step or to purify the reaction intermediate. Moreover, high chemoselectivity of the tested ω‐TAs for the saturated ketones was shown in the cascade reactions.
Azido‐Substituted BODIPY Dyes for the Production of Fluorescent Carbon Nanotubes
Authors: Fedeli Stefano , Paoli Paolo , Brandi Alberto , Venturini Lorenzo , Giambastiani Giuliano , Tuci Giulia , Cicchi Stefano 
Published: August 2015

AbstractA series of azido‐dyes were synthesized through Knoevenagel reactions of an azido‐BODIPY with aromatic aldehydes. The nature of the substituents allowed the fine tuning of their spectroscopic properties. The dyes were used to decorate oxidized multiwalled carbon nanotubes (ox‐MWCNTs), bearing terminal triple bond groups, by CuAAC reactions, affording fluorescent materials. This decoration allowed the efficient determination of the internalization of the ox‐MWCNT derivatives by different model cancer cells, such as MCF7.
Factors Controlling β‐Elimination Reactions in Group 10 Metal Complexes
Authors: Sosa Carrizo E. Daiann , Bickelhaupt F. Matthias , Fernández Israel 
Published: August 2015

AbstractTrends in reactivity of β‐chloride and β‐hydride elimination reactions involving Group 10 transition‐metal complexes have been computationally explored and analyzed in detail by DFT. These reactions do not require the initial formation of a vacant coordination site; they proceed concertedly without a prior ligand‐dissociation step. Whereas β‐chloride elimination is associated with relatively moderate activation barriers, the high barriers calculated for analogous β‐hydride eliminations suggest that the latter process is unfeasible for this type of compounds. This differential behavior is analyzed within the activation strain model, which provides quantitative insight into the physical factors controlling these β‐elimination reactions. The effects of the nature of the Group 10 transition metal (Ni, Pd, Pt), as well as the substituents attached to the β‐eliminating fragment (R2CCR2X; R, X=H, Cl) on the transformation have also been considered and are rationalized herein.