bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inter‐residue interactions in protein structures exhibit power‐law behavior
Authors: Gao Jun , Li Zhijun 
Published: August 2008

AbstractInter‐residue interactions play an essential role in driving protein folding, and analysis of these interactions increases our understanding of protein folding and stability and facilitates the development of tools for protein structure and function prediction. In this work, we systematically characterized the change of inter‐residue interactions at various sequence separation cutoffs using two protein datasets. The first set included 100 diverse, nonredundant and high‐resolution soluble protein structures, covering all four major structural classes, all‐α, α/β, α+β, and all‐β; and the second set included 20 diverse, nonredundant and high‐resolution membrane protein structures, representing 19 unique superfamilies. It was shown that the average number of inter‐residue interactions in structures of both datasets displays the power‐law behavior. Fitting parameters of the power‐law function are directly related to the structural classes analyzed. These findings provided further insight into the distribution of short‐, medium‐, and long‐range inter‐residue interactions in both soluble and membrane proteins and could be used for protein structure prediction. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1174–1178, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Ruthenium(II) Pyridylamine Complexes with Diimine Ligands Showing Reversible Photochemical and Thermal Structural Change
Authors: Kojima Takahiko , Morimoto Tsuyoshi , Sakamoto Taisuke , Miyazaki Soushi , Fukuzumi Shunichi 
Published: August 2008

AbstractRuthenium(II)–TPA–diimine complexes, [Ru(TPA)(diimine)]2+ (TPA=tris(2‐pyridylmethyl)amine; diimine=2,2′‐bipyridine (bpy), 2,2′‐bipyrimidine (bpm), 1,10‐phenanthroline (phen)) were synthesized and characterized by spectroscopic and crystallographic methods. Their crystal structures demonstrate severe steric hindrance between the TPA and diimine ligands. They exhibit drastic structural changes on heating and photoirradiation at their MLCT bands, which involve partial dissociation of the tetradentate TPA ligand to exhibit a facially tridentate mode accompanied by structural change and solvent coordination to give [Ru(TPA)(diimine)(solvent)]2+ (solvent=acetonitrile, pyridine). The incoming solvent molecules are required to have π‐acceptor character, since σ‐donating solvent molecules do not coordinate. The thermal process is irreversible dissociation to give the solvent‐bound complexes, which takes place by an interchange associative mechanism with large negative activation entropies. The photochemical process is a reversible reaction reaching a photostationary state, probably by a dissociative mechanism involving a five‐coordinate intermediate to afford the same product as obtained in the thermal reaction. Quantum yields of the forward reactions to give dissociated products were lower than those of the backward reactions to recover the starting complexes. In the photochemical process, the conversions of the forward and backward reactions depend on the absorption coefficients of the starting materials and those of the products at certain wavelength, as well as the quantum yields of those reactions. The reversibility of the motions can be regulated by heating and by photoirradiation at certain wavelength for the recovery process. In the bpm system, we could achieve about 90 % recovery in thermal/photochemical structural interconversion.
Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy
Authors: Cambré Sofie , Wenseleers Wim , Čulin Jelena , Van Doorslaer Sabine , Fonseca Antonio , Nagy Janos B. , Goovaerts Etienne 
Published: August 2008

AbstractSingle‐walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by π–π‐stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99 % of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red‐shifted compared to the free porphyrin absorption. In addition a quasi‐complete quenching of the porphyrin fluorescence is also observed.
Cooperativity between the Dihydrogen Bond and the N⋅⋅⋅HC Hydrogen Bond in LiH–(HCN)nComplexes
Authors: Li Qing‐Zhong , Hu Ting , An Xiu‐Lin , Gong Bao‐An , Cheng Jian‐Bo 
Published: August 2008

AbstractThe cooperativity between the dihydrogen bond and the N⋅⋅⋅HC hydrogen bond in LiH–(HCN)n(n=2 and 3) complexes is investigated at the MP2 level of theory. The bond lengths, dipole moments, and energies are analyzed. It is demonstrated that synergetic effects are present in the complexes. The cooperativity contribution of the dihydrogen bond is smaller than that of the N⋅⋅⋅HC hydrogen bond. The three‐body energy in systems involving different types of hydrogen bonds is larger than that in the same hydrogen‐bonded systems. NBO analyses indicate that orbital interaction, charge transfer, and bond polarization are mainly responsible for the cooperativity between the two types of hydrogen bonds.
An area‐efficient switched‐capacitor relaxation oscillator with digitally controlled frequency tunability
Authors: Ausín José L. , Ramos J. , Torelli G. , Duque‐Carrillo J. F. 
Published: August 2008

AbstractThis paper describes a programmable low‐jitter switched‐capacitor (SC) square‐wave oscillator for the use in a variety of voice‐band signal‐processing applications. The core of the circuit is a relaxation oscillator whose oscillation frequency programmability does not resort to variations either in capacitor values or in the sampling frequency. As a result, total capacitance is reduced and, hence, silicon area is minimized while low phase jitter and high resolution programmability are achieved. Simulation results referred to the design of an SC oscillator in 0.35‐µm CMOS technology are presented to demonstrate the feasibility of the proposed approach. Copyright © 2008 John Wiley & Sons, Ltd.
The vesicular integral protein‐like gene is essential for development of a mechanosensory system in zebrafish
Authors: Chong Mabel , Liao Meijiang , Drapeau Pierre 
Published: August 2008

AbstractThe zebrafish hi472 mutation is caused by a retroviral insertion into the vesicular integral protein‐like gene, or zVIPL, a poorly studied lectin implicated in endoplasmic reticulum (ER)‐Golgi trafficking. A mutation in the shorter isoform of zVIPL (zVIPL‐s) results in a reduction of mechanosensitivity and consequent loss of escape behavior. Here we show that motoneurons and hindbrain reticulospinal neurons, which normally integrate mechanosensory inputs, failed to fire in response to tactile stimuli in hi472 larvae, suggesting a perturbation in sensory function. The hi472 mutant larvae in fact suffered from a severe loss of functional neuromasts of the lateral line mechanosensory system, a reduction of zVIPL labeling in support cells, and a reduction or even a complete loss of hair cells in neuromasts. The Delta‐Notch signaling pathway is implicated in cellular differentiation of neuromasts, and we observed an increase in Notch expression in neuromasts of hi472 mutant larvae. Treatment of hi472 mutant larvae with DAPT, an inhibitor of Notch signaling, or overexpression of the Notch ligand deltaB in hi472 mutant blastocysts produced partial rescue of the morphological defects and of the startle response behavior. We conclude that zVIPL‐s is a necessary component of Delta‐Notch signaling during neuromast development in the lateral line mechanosensory system. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Absence of arterial phenotype in mice with homozygous slc2A10 missense substitutions
Authors: Callewaert B.L. , Loeys B.L. , Casteleyn C. , Willaert A. , Dewint P. , De Backer J. , Sedlmeier R. , Simoens P. , De Paepe A.M. , Coucke P.J. 
Published: August 2008

AbstractArterial tortuosity syndrome (ATS, MIM# 208050) is a rare autosomal recessive connective tissue disease, mainly characterized by widespread arterial involvement with elongation, tortuosity, and aneurysms of the large and middle‐sized arteries (Callewaert et al., 2008, Hum Mutat 29:150–158). Recently, mutations were identified in the SLC2A10 gene encoding the facilitative glucose transporter GLUT10 (Coucke et al., 2006, Nat Genet 38:452–457). It was hypothesized that loss‐of‐function of the transporter results in upregulation of the transforming growth factor beta (TGFβ) signaling pathway (Coucke et al., 2006, Nat Genet 38:452–457). We anticipated that a mouse model would help to gain more insight in the complex pathophysiological mechanism of human ATS. Here, we report that two mouse models, homozygous respectively for G128E and S150F missense substitutions in glut10 do not present any of the vascular, anatomical, or immunohistological abnormalities as encountered in human ATS patients. We conclude that these mouse strains do not phenocopy human ATS and cannot help the further elucidation of pathogenetic mechanisms underlying this disease. genesis 46:385–389, 2008. © 2008 Wiley‐Liss, Inc.
Targeting of endothelin receptor‐B to the neural crest
Authors: Druckenbrod Noah R. , Powers Patricia A. , Bartley Christopher R. , Walker Jeffery W. , Epstein Miles L. 
Published: August 2008

AbstractEndothelin receptor B (Ednrb) plays a critical role in the development of melanocytes and neurons and glia of the enteric nervous system. These distinct neural crest‐derived cell types express Ednrb and share the property of intercalating into tissues, such as the intestine whose muscle precursor cells also express Ednrb. Such widespread Ednrb expression has been a significant obstacle in establishing precise roles for Ednrb in development. We describe here the production of an Ednrb allele floxed at exon 3 and its use in excising the receptor from mouse neural crest cells by use of Cre‐recombinase driven by the Wnt1 promoter. Mice born with neural crest‐specific excision of Ednrb possess aganglionic colon, lack trunk pigmentation, and die within 5 weeks due to megacolon. Ednrb receptor expression in these animals is absent only in the neural crest but present in surrounding smooth muscle cells. The absence of Ednrb from crest cells also results in a compensatory upregulation of Ednrb expression in other cells within the gut. We conclude that Ednrb loss only in neural crest cells is sufficient to produce the Hirschsprungs disease phenotype observed with genomic Ednrb mutations. genesis 46:396–400, 2008. © 2008 Wiley‐Liss, Inc.
Generation of a conditional mutant allele for Tab1 in mouse
Authors: Inagaki Maiko , Komatsu Yoshihiro , Scott Greg , Yamada Gen , Ray Manas , Ninomiya‐Tsuji Jun , Mishina Yuji 
Published: August 2008

AbstractTAK1 binding protein 1 (TAB1) binds and induces autophosphorylation of TGF‐β activating kinase (TAK1). TAK1, a mitogen‐activated kinase kinase kinase, is involved in several distinct signaling pathways including non‐Smad pathways for TGF‐β superfamily members and inflammatory responses caused by cytokines. Conventional disruption of the murine Tab1 gene results in late gestational lethality showing intraventricular septum defects and underdeveloped lung alveoli. To gain a better understanding of the roles of TAB1 in different tissues, at different stages of development, and in pathological conditions, we generated Tab1 floxed mice in which the loxP sites flank Exons 9 and 10 to remove the C‐terminal region of TAB1 protein necessary for activation of TAK1. We demonstrate that Cre‐mediated recombination using Sox2‐Cre, a Cre line expressed in the epiblast during early embryogenesis, results in deletion of the gene and protein. These homozygous Cre‐recombined null embryos display an identical phenotype to conventional null embryos. This animal model will be useful in revealing distinct roles of TAB1 in different tissues at different stages. genesis 46:431–439, 2008. Published 2008 Wiley‐Liss, Inc.
Palladastannatrane – a PdII→SnIV Dative Bond
Authors: Wagler Jörg , Hill Anthony F. , Heine Thomas 
Published: August 2008

AbstractThe reaction of N‐methyl‐2‐mercaptoimidazole (methimazole, Hmt) with NaN(SiMe3)2, [PdCl2(L)2] (L = PPh3, NCMe) and SnCl4 provides the novel tetrabicyclo[3.3.3.3.0] lantern compound [PdSn(μ‐mt)4Cl2] (1) in which a dative PdII→SnIV bond is housed within the cage structure. Single‐crystal X‐ray diffraction analysis reveals a Pd–Sn separation of 2.605(1) Å in this compound, and the cation [PdSn(mt)4Cl]+ was detected by ESI‐MS analysis of an acetonitrile solution of [PdSn(μ‐mt)4Cl2]. Quantum chemical analysis of the Pd–Sn bonding situation revealed predominant electrostatic interactions between the positively charged Sn and the negatively charged Pd atom. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Hollow‐Sphere Nanostructures of Optically Active Metal‐Free Phthalocyanine
Authors: Lv Wei , Zhang Xiaomei , Lu Jitao , Zhang Yuexing , Li Xiyou , Jiang Jianzhuang 
Published: August 2008

AbstractOptically active metal‐free phthalocyanine (1) decorated with four octyl chains linked through binaphthyl units to the phthalocyanine ring was designed and prepared. This compound was characterized by a wide range of spectroscopic methods in addition to elemental analysis. By employing a solution injection method, both the (R) and (S) enantiomers self‐assemble into nanoparticles. Surprisingly, with the addition of a small amount of cetyltrimethylammonium bromide (CTAB), nanostructures with hollow‐sphere morphologies were formed. The hollow‐spherical structure was determined by transmission electronic microscopy and scanning electronic microscopy. X‐ray photoelectron spectroscopy together with FTIR spectra indicates the supramolecular structures formed from the metal‐free phthalocyanine molecules. Low‐angle X‐ray diffraction reveals the stacked phthalocyanine molecules with a face‐to‐face configuration in the nanoscale hollow spheres formed with the help of CTAB surfactant. The formation of H‐aggregates in the nanoscale hollow spheres is further confirmed by electronic absorption spectroscopic result. This work, representing the first example of controllable organic nanostructures with a hollow sphere morphology fabricated from phthalocyanine provides an effective method towards phthalocyanine hollow nanospheres.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Biotransformation of glycerol into 1,3‐propanediol
Authors: Willke Thomas , Vorlop Klaus 
Published: August 2008

AbstractToday, glycerol is mainly a by‐product of fat splitting and biodiesel production. Further growth of the biodiesel market would result in a fall in the price of glycerol. Particularly glycerol‐water from rapeseed oil methyl ester production, for example, would be an interesting raw material if it could be utilised in fermentation without further pretreatment. Under anaerobic conditions, bacteria can transform glycerol into 1,3‐propanediol (PDO), which can be used as a monomer in the chemical industry. PDO can be produced biotechnologically from glycerol with the aid of bacteria. Another way would be the utilization of glucose instead of glycerol, which would provide independence from the fluctuating glycerol market. However, under certain conditions, the classic technique based on glycerol can be quite interesting with regard to technical and economic aspects: A concerted, extensive search for new microorganisms (screening) and improved process design (fed‐batch with pH‐controlled substrate dosage) allowed the product concentrations, which were relatively low at a maximum of 70–80 g/L as a result of product inhibition, to be raised to more than 100 g/L. An additional advantage of the new technique and the newly isolated strains is the utilisation of low‐priced crude glycerol or glycerol‐water. This is a factor which should not be underestimated and has a direct effect on the product costs. Further on, the use of immobilised cells compared to freely suspended cells enables an increase of productivity from about 2 up to 30 g /Lh.
1‐Oxoniaadamantane
Authors: Etzkorn Markus , Aniszfeld Robert , Li Tiejun , Buchholz Herwig , Rasul Golam , Prakash G. K. Surya , Olah George A. 
Published: August 2008

AbstractThe missing member of the heteroadamantane series, 1‐oxoniaadamantane (4a), was prepared by the ionization of suitable bicyclic precursors under strongly acidic conditions. The ion 4a was characterized by 1H and 13C NMR spectroscopy. The X‐ray crystal structure of ion 4a was also obtained with a CB11H6Cl6 counter anion. DFT calculations were performed on 1‐elementaadamantane cations for comparison. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electrocatalytic Oxidation and Voltammetric Determination of Nitrite on Hydrophobic Ionic Liquid‐Carbon Nanotube Gel‐Chitosan Composite Modified Electrodes
Authors: Xiao Fei , Liu Liqin , Li Jun , Zeng Junjie , Zeng Baizhao 
Published: August 2008

AbstractA novel room temperature ionic liquid (i.e., 1‐octyl‐3‐methylimidazolium hexafluorophosphate, OMIMPF6)‐multiwall carbon nanotube (MWNT) gel‐chitosan (Chi) composite modified glassy carbon electrode (GCE) was fabricated and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The OMIMPF6‐MWNT gel‐Chi composite showed good conductivity, stability, and extraction effect due to the synergic action of OMIMPF6, MWNT, and Chi. Furthermore, it was found that the OMIMPF6‐MWNT gel‐Chi composite had strong electrocatalytic effect on the oxidation of nitrite and at the OMIMPF6‐MWNT gel‐Chi/GCE nitrite could produce a very sensitive anodic peak. Under optimized conditions, the peak current was linear to nitrite concentration from 2.0×10−8 to 6.0×10−5 M. The detection limit was 1.0×10−8 M. The electrode also exhibited acceptable stability, repeatability and selectivity. It was used successfully for the determination of nitrite in soil, sewage and sausage samples.
A Selective and Sensitive Method for Simultaneous Determination of Traces of Paracetamol and p‐Aminophenol in Pharmaceuticals Using Carbon Ionic Liquid Electrode
Authors: Safavi Afsaneh , Maleki Norouz , Moradlou Omran 
Published: August 2008

AbstractA reliable and simple electrochemical method has been proposed for the simultaneous determination of paracetamol (PAR) and p‐aminophenol (PAP) in pharmaceutical formulations. The oxidation and reduction peak potentials in cyclic voltammetry (CV) for PAR on carbon ionic liquid electrode (CILE) were occurred at 370 and 225 mV vs. Ag/AgCl, respectively at pH 7.0, while those for PAP on CILE appeared at 128 mV and 68 mV, respectively at the scan rate of 0.05 V s−1. In comparison to the conventional carbon paste electrode, the apparent reversibility and kinetics of the electrochemical reactions of PAR and PAP were significantly improved on CILE. In differential pulse voltammetric technique, the peak potentials for PAR and PAP appeared at 345 and 130 mV, respectively, with the peak separation of 215 mV, sufficient for their simultaneous determination in samples containing these two species. The proposed method was used for simultaneous determination of PAR and PAP in tablets. PAR and PAP can be determined in the ranges of 2.0×10−6–2.2×10−3 M and 3.0×10−7–1.0×10−3 M, with the detection limits of 5.0×10−7 and 1.0×10−7 M (calculated by 3σ), respectively. The relative standard deviations for the determination of PAR and PAP were less than 2%.
Iridium Oxide Film Electrodes for Anodic Stripping Voltammetry
Authors: Hull Ewa , Piech Robert , Kubiak Władysław W. 
Published: August 2008

AbstractThe new iridium oxide film electrode, applied for the determination of lead(II), cadmium(II) and copper(II) traces using differential pulse anodic stripping voltammetry (DP ASV) is presented. The electrode display an interesting stripping voltammetric performance which compares with electrodes commonly used in voltammetry. The deposited film is known as anodically electrodeposited iridium oxide film (AEIROF). The AEIROF electrode is characterized by long‐term stability (more than 40 days) and very good reproducibility of the analytical signals in this time (≤12% for 0.5 μM of lead). The regeneration of iridium film is very simple in a time shorter than 60 seconds. The effects of various factors such as: thickness of AEIROF film, preconcentration potential and time, supporting electrolyte composition, potential interferences are optimized. The detection limit for AEIROF film electrode based on glassy carbon for an accumulation time of 30 s is as low as 7 nM for lead(II). The repeatability of the method at a concentration level of the lead(II) as low as 0.5 μM, expressed as RSD is 2.5% (n=10). The proposed method was successfully applied and validated by studying certified reference material CTA‐OTL‐1. Such an attractive use of ‘mercury–free’ ‐ environmentally friendly electrodes offers great promise to measure trace metals.
A Mediator‐Free Bienzyme Amperometric Biosensor Based on Horseradish Peroxidase and Glucose Oxidase Immobilized on Carbon Nanotube Modified Electrode
Authors: Yao Yan‐Li , Shiu Kwok‐Keung 
Published: August 2008

AbstractMultiwalled carbon nanotube (CNT) modified glassy carbon electrode immobilized with horseradish peroxidase (HRP) in Nafion coating showed direct electron transfer between HRP enzyme and the CNT‐modified electrode. A mediator‐free bienzyme glucose biosensor based on horseradish peroxidase and glucose oxidase was constructed. The bienzyme biosensor exhibited a high sensitivity for glucose detection at zero applied potential.
Improved Voltammetric Response of L‐Tyrosine on Multiwalled Carbon Nanotubes‐Ionic Liquid Composite Coated Glassy Electrodes in the Presence of Cupric Ion
Authors: Liu Liqin , Zhao Faqiong , Xiao Fei , Zeng Baizhao 
Published: August 2008

AbstractL‐Tyrosine can exhibit a small anodic peak on multiwalled carbon nanotubes (MWCNTs) coated glassy carbon electrodes (GCE). At pH 5.5 its peak potential is 0.70 V (vs. SCE). When an ionic liquid (i.e., 1‐octyl‐3‐methylimidazolium hexafluorophosphate, [omim][PF6]) is introduced on the MWCNT coat, the peak becomes bigger. Furthermore, in the presence of Cu2+ ion the anodic peak of L‐tyrosine increases further due to the formation of Cu2+‐L‐tyrosine complex, while the peak potential keeps unchanged. Therefore, a sensitive voltammetry based on the oxidation of Cu2+‐L‐tyrosine complex on MWCNTs‐[omim][PF6] composite coated electrode is developed for L‐tyrosine. Under the optimized conditions, the anodic peak current is linear to L‐tyrosine concentration in the range of 1×10−8–5×10−6 M, and the detection limit is 8×10−9 M. The modified electrode shows good reproducibility and stability. In addition, the voltammetric behavior of other amino acids is explored. It is found that among them tryptophan (Trp) and histidine (His) can also produce sensitive anodic peak under same experimental conditions, and their detection limits are 4×10−9 M and 4×10−6 M, respectively.