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Ryan Mahling, Adina M Kilpatrick, Madeline A Shea
Human voltage-gated sodium channel NaV1.2 has a single pore-forming α-subunit and two transmembrane β-subunits. Expressed primarily in the brain, NaV1.2 is critical for initiation and propagation of action potentials. Milliseconds after the pore opens, sodium influx is terminated by inactivation processes mediated by regulatory proteins including calmodulin (CaM). Both calcium-free (apo) CaM and calcium-saturated CaM bind tightly to an IQ motif in the C-terminal tail of the α-subunit. Our thermodynamic studies and solution structure (2KXW) of a C-domain fragment of apo (13)C,(15)N- CaM (CaMC) bound to an unlabeled peptide with the sequence of rat NaV1...
August 19, 2017: Biomolecular NMR Assignments
Jingyu Pang, Yanhong Chao, Honghong Chang, Hongping Li, Jun Xiong, Minqiang He, Qi Zhang, Huaming Li, Wenshuai Zhu
In this paper, the carbon-doped boron nitride nanoplate (C-BNNP) was prepared by pyrolyzing the precursor under N2 and served as an excellent adsorbent for removal of Rhodamine B (RhB). The structure and composition of C-BNNP were characterized and its adsorption behavior for RhB was investigated. Compared with boron nitride nanoplate (BNNP) which was synthesized under NH3, C-BNNP displayed an enhancement of the adsorption capacity for RhB (833mg/g). The adsorption activity was comprehensibly studied by kinetics, isotherm and thermodynamics...
August 4, 2017: Journal of Colloid and Interface Science
Fande Meng, Guodong Yuan, Jing Wei, Dongxue Bi, Hailong Wang
Adsorption is an important mechanism to immobilize cadmium (Cd) in soil, for which humic substances have a potential. However, commercial humic substances are either very acidic (pH = 2) or alkaline/Na(+)-enriched, making them less suitable for use in acid and saline soils. Here, we used leonardite to produce humic adsorbents HA (pH = 4.02), Ca-HA (pH = 10.9), and Ca-CPAM-HA (pH = 9.62) by using HCl, CaCl2, or CaCl2-polyacrylamide as a flocculant. Their elemental compositions, acidity, and spectroscopic properties were determined, and their Cd adsorption characteristics were assessed by batch kinetic and thermodynamic experiments at environmentally relevant concentrations...
August 18, 2017: Environmental Science and Pollution Research International
Song-Ho Chong, Sihyun Ham
Interfacial waters are considered to play a crucial role in protein-protein interactions, but in what sense and why are they important? Here, using molecular dynamics simulations and statistical thermodynamic analyses, we demonstrate distinctive dynamic characteristics of the interfacial water and investigate their implications for the binding thermodynamics. We identify the presence of extraordinarily slow (~1,000 times slower than in bulk water) hydrogen-bond rearrangements in interfacial water. We rationalize the slow rearrangements by introducing the "trapping" free energies, characterizing how strongly individual hydration waters are captured by the biomolecular surface, whose magnitude is then traced back to the number of water-protein hydrogen bonds and the strong electrostatic field produced at the binding interface...
August 18, 2017: Scientific Reports
Pankaj Attri, Minsup Kim, Thapanut Sarinont, Eun Ha Choi, Hyunwoong Seo, Art E Cho, Kazunori Koga, Masaharu Shiratani
Both gamma rays and atmospheric pressure plasma are known to have anticancer properties. While their mechanism actions are still not clear, in some contexts they work in similar manner, while in other contexts they work differently. So to understand these relationships, we have studied Myoglobin protein after the treatment of gamma rays and dielectric barrier discharge (DBD) plasma, and analyzed the changes in thermodynamic properties and changes in the secondary structure of protein after both treatments. The thermodynamic properties were analyzed using chemical and thermal denaturation after both treatments...
August 18, 2017: Scientific Reports
Shin-Joung Rho, Saehun Mun, Jung Sun Hong, Young-Lim Kim, Ha V Do, Young-Wan Kim, Sang-Ik Han, Yong-Ro Kim
The complex formation capability of cycloamylose (CA), having a degree of polymerization of 23-45, with phenolic compounds (PCs) was investigated using various physicochemical techniques. The fluorescence intensity of PCs increased and then reached a plateau at 10-20mM cyclodextrin, while it continued to increase at up to 60mM CA. Thermodynamic data of CA complexes with PCs revealed that the binding process was primarily enthalpy-driven and spontaneous. CA favored to form the most stable complex with chlorogenic acid (CHA) among all PCs...
October 15, 2017: Carbohydrate Polymers
Soodamani Periyasamy, Venkatrajan Gopalakannan, Natrayasamy Viswanathan
The present study was focused on Cr(VI) removal using eco-friendly materials like cellulose (Cel), hydrotalcite (HT), hydroxyapatite (HAp) and their composite forms. The cellulose/hydrotalcite (CelHT) and cellulose/hydroxyapatite (CelHAp) composites were synthesized by dispersing HT and HAp individually in cellulose polymeric matrix. To enhance the Cr(VI) sorption capacity (SC) and easy separation, cellulose supported magnetic composites namely iron-oxide coated cellulose/hydrotalcite (Fe3O4@CelHT) and cellulose/hydroxyapatite (Fe3O4@CelHAp) were synthesized by in situ fabrication method...
October 15, 2017: Carbohydrate Polymers
Frank-Dieter Kopinke, Anett Georgi, Ulf Roland
Diffusive isotope fractionation of organic compounds in aqueous solution was investigated by means of liquid-liquid and liquid-gas partitioning experiments under kinetic control. The two-film model was used to describe phase-transfer kinetics. It assumes the diffusion of solutes across a stagnant water boundary layer as the rate-controlling step. For all investigated solutes (benzene-D0 and -D6, toluene-D0, -D5, and -D8, cyclohexane-D0 and -D12), there was no significant observable fractionation effect between nondeuterated and perdeuterated isotopologues, resulting in a ratio of diffusion coefficients Dlight: Dheavy=1...
August 15, 2017: Science of the Total Environment
Mhamad Aly Moussawi, Nathalie Leclerc-Laronze, Sébastien Floquet, Pavel A Abramov, Maxim Nailyevich Sokolov, Stephane Cordier, Anne Ponchel, Eric Monflier, Herve Bricout, David Landy, Mohamed Haouas, Jerome Marrot, Emmanuel Cadot
Herein, we report on a three-component supramolecular hybrid system built from specific recognition processes involving a Dawson type polyoxometalate [P2W18O62](6-,) a cationic electron-rich cluster {[Ta6Br12(H6O)6]@2CD}(2+) and γ-cyclodextrin. Investigations of such a class of materials have been conducted using bottom-up approach by studying the specific interactions between -CD and both types of inorganic units. Their ability to interact has been investigated in the solid state by single-crystal X-ray diffraction and in solution using multinuclear NMR methods (including DOSY, EXSY and COSY), ESI-mass and UV-vis spectroscopies, electrochemistry and ITC experiments...
August 18, 2017: Journal of the American Chemical Society
Kwang Hun Lim, Anvesh K R Dasari, Renze Ma, Ivan Hung, Zhehong Gan, Jeffery W Kelly, Michael C Fitzgerald
Amyloid formation of natively folded proteins involves global and/or local unfolding of the native state to form aggregation-prone intermediates. Here we report solid-state NMR structural studies of amyloid derived from wild-type (WT) and more aggressive mutant forms of transthyretin (TTR) to investigate the structural changes associated with effective TTR aggregation. We employed selective 13C-labeling schemes to investigate structural features of β-structured core regions in amyloid states of WT and two mutant forms (V30M and L55P) of TTR...
August 18, 2017: Biochemistry
Andrej Skerencak-Frech, Michael Trumm, Daniel R Fröhlich, Petra J Panak
The complexation of Cm(III) with malonate is studied by time-resolved laser fluorescence spectroscopy (TRLFS) in the temperature range from 25 to 90 °C. Three complexes ([Cm(Mal)n](3-2n), n = 1, 2, 3) are identified and their molar fractions are determined as a function of the ligand concentration, the ionic strength, and the temperature. A general shift of the chemical equilibrium toward higher complexes with increasing temperature is observed, with the [CmMal3](3-) complex forming only at T > 40 °C. The conditional stability constants (log K'n(T)) are calculated and extrapolated to Im = 0 with the specific ion interaction theory (SIT)...
August 18, 2017: Inorganic Chemistry
Jacob C Dean, Ruomeng Zhang, Rawad K Hallani, Ryan D Pensack, Samuel N Sanders, Daniel G Oblinsky, Sean R Parkin, Luis M Campos, John E Anthony, Gregory D Scholes
Quantitative singlet fission has been observed for a variety of acene derivatives such as tetracene and pentacene, and efforts to extend the library of singlet fission compounds is of current interest. Preliminary calculations suggest anthradithiophenes exhibit significant exothermicity between the first optically-allowed singlet state, S1, and 2 × T1 with an energy difference of >5000 cm(-1). Given the fulfillment of this ingredient for singlet fission, here we investigate the singlet fission capability of a difluorinated anthradithiophene dimer (2ADT) covalently linked by a (dimethylsilyl)ethane bridge and derivatized by triisobutylsilylethynyl (TIBS) groups...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
Thomas W J Nicol, Noriyuki Isobe, James H Clark, Seishi Shimizu
In the study of the cellulose dissolution mechanism opinion is still divided. Here, the solution interaction components of the most prominent hypotheses for the driving force of cellulose dissolution were evaluated quantitatively. Combining a rigorous statistical thermodynamic theory and cellobiose solubility data in the presence of chloride salts, whose cations progress in the Hofmeister series (KCl, NaCl, LiCl and ZnCl2), we have shown that cellobiose solubilization is driven by the preferential accumulation of salts around the solutes which is stronger than cellobiose hydration...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
Arundhati Banerjee, Rakhi Dasgupta, Sujay Ray
INTRODUCTION: With advances in proteomics, it is essential to investigate the molecular-level participation of IL27 and gp130 to hinder HIV infection. Their interaction causes cell-cycle arrest in HIV+ cells by activating the receptor-associated JAK signaling and causing apoptosis of cancerous cells. METHODOLOGY: The best human wild-type WT_IL27 model was prepared after varied molecular modeling techniques. The vital tyrosine residues in WT_IL27 were identified, mutated and IL27 was re-modeled...
August 17, 2017: Current HIV Research
Mohamed Shaban, Mohamed E M Hassouna, Fadya M Nasief, Mostafa R AbuKhadra
Raw kaolinite was used in the synthesis of metakaolinite/carbon nanotubes (K/CNTs) and kaolinite/starch (K/starch) nanocomposites. Raw kaolinite and the synthetic composites were characterized using XRD, SEM, and TEM techniques. The synthetic composites were used as adsorbents for Fe and Mn ions from aqueous solutions and natural underground water. The adsorption by the both composites is highly pH dependent and achieves high efficiency within the neutral pH range. The experimental adsorption data for the uptake of Fe and Mn ions by K/CNTs were found to be well represented by the pseudo-second-order kinetic model rather than the intra-particle diffusion model or Elovich model...
August 17, 2017: Environmental Science and Pollution Research International
Mateen A Khan, William E Walden, Elizabeth C Theil, Dixie J Goss
Comparison of kinetic and thermodynamic properties of IRP1 (iron regulatory protein1) binding to FRT (ferritin) and ACO2 (aconitase2) IRE-RNAs, with or without Mn(2+), revealed differences specific to each IRE-RNA. Conserved among animal mRNAs, IRE-RNA structures are noncoding and bind Fe(2+) to regulate biosynthesis rates of the encoded, iron homeostatic proteins. IRP1 protein binds IRE-RNA, inhibiting mRNA activity; Fe(2+) decreases IRE-mRNA/IRP1 binding, increasing encoded protein synthesis. Here, we observed heat, 5 °C to 30 °C, increased IRP1 binding to IRE-RNA 4-fold (FRT IRE-RNA) or 3-fold (ACO2 IRE-RNA), which was enthalpy driven and entropy favorable...
August 17, 2017: Scientific Reports
S Shahab Naghavi, Antoine A Emery, Heine A Hansen, Fei Zhou, Vidvuds Ozolins, Chris Wolverton
Previous studies have shown that a large solid-state entropy of reduction increases the thermodynamic efficiency of metal oxides, such as ceria, for two-step thermochemical water splitting cycles. In this context, the configurational entropy arising from oxygen off-stoichiometry in the oxide, has been the focus of most previous work. Here we report a different source of entropy, the onsite electronic configurational entropy, arising from coupling between orbital and spin angular momenta in lanthanide f orbitals...
August 18, 2017: Nature Communications
Xiaolan Zhao, Shirong Qiang, Hanyu Wu, Yunbo Yang, Dadong Shao, Linchuan Fang, Jianjun Liang, Ping Li, Qiaohui Fan
The sorption mechanism of nickel (Ni) at the illite/water interface was investigated using batch, sorption modelling, extended X-ray absorption fine structure (EXAFS), and extraction approaches. The results showed that Ni(II) sorption on illite was strongly dependent on pH, contact time, temperature, and initial Ni(II) concentration. At a low initial Ni(II) concentration, the ion exchange species of ≡X2Ni° and the inner-sphere complexes including ≡S(s)ONi(+), ≡S(w)ONi(+) and ≡S(w)ONiOH° species are observed on the sorption edges of Ni(II) on illite...
August 17, 2017: Scientific Reports
Shyam M Garg, Igor M Paiva, Mohammad R Vakili, Rania Soudy, Kate Agopsowicz, Amir H Soleimani, Mary Hitt, Kamaljit Kaur, Afsaneh Lavasanifar
Traceable poly(ethylene oxide)-poly(ester) micelles were developed through chemical conjugation of a near-infrared (NIR) dye to the poly(ester) end by click chemistry. This strategy was tried for micelles with poly(ε-caprolactone) (PCL) or poly(α-benzyl carboxylate-ε-caprolactone) (PBCL) cores. The surface of both micelles was also modified with the breast cancer targeting peptide, P18-4. The results showed the positive contribution of PBCL over PCL core on micellar thermodynamic and kinetic stability as well as accumulation in primary orthotopic MDA-MB-231 tumors within 4-96 h following intravenous administration in mice...
August 4, 2017: Biomaterials
Ping Zhang, Irene Lo, David O'Connor, Simo Pehkonen, Hefa Cheng, Deyi Hou
Recent studies have shown that hazardous organic dye substances can be removed from aqueous solutions by spinel ferrite nanomaterials. We found that Sodium Dodecyl Sulfonate (SDS) surface-modified mesoporous ZnFe2O4 nanoparticles (10-50nm) have a remarkably high maximum adsorptive capacity (∼699.30mg/g) for aqueous Methylene Blue (MB) removal at T of 288K and pH of 12. Unmodified ZnFe2O4 nanoparticles suffer from particle agglomeration, which reduces surface area, thus reducing their adsorptive capacity. Here it is shown that when modified with SDS, the specific surface area increased by ∼34%...
August 9, 2017: Journal of Colloid and Interface Science
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