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https://www.readbyqxmd.com/read/28735167/first-observation-of-metal-ion-induced-structural-fluctuations-of-%C3%AE-helical-peptides-by-using-diffracted-x-ray-tracking
#1
Daiki Usui, Satomi Inaba, Hiroshi Sekiguchi, Yuji C Sasaki, Toshiki Tanaka, Masayuki Oda
In order to analyze protein structural dynamics, we designed simple model peptides whose structures changed from random-coil to helix-bundle structures by forming stable hydrophobic core in the presence of metal ions. The strategy involved destabilizing a de novo designed three helix-bundle protein by substituting the residues present in its hydrophobic core with histidine and small amino acids. The conformational changes of peptides induced upon binding of Zn(2+) to histidine were analyzed using circular dichroism spectroscopy, which revealed peptides, HA and HG, to be good candidates for further analyses...
July 14, 2017: Biophysical Chemistry
https://www.readbyqxmd.com/read/28734785/impact-of-magnetic-stirring-on-stainless-steel-integrity-effect-on-biopharmaceutical-processing
#2
Christopher Thompson, Kelly Wilson, Yoen Joo Kim, Min Xie, William K Wang, Michaela Wendeler
Stainless steel containers are widely used in the pharmaceutical and biopharmaceutical industry for the storage of buffers, process intermediates, and purified drug substance. They are generally held to be corrosion resistant, biocompatible, and non-reactive, although it is well established that trace amounts of metal ions can leach from stainless steel equipment into biopharmaceutical products. We report here that the use of stainless steel containers in conjunction with magnetic stirring bars leads to significantly aggravated metal contamination, consisting both of metal particles and significantly elevated metal ions in solution, the degree of which is several orders of magnitude higher than described for static conditions...
July 19, 2017: Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28734367/a-solid-contact-potassium-selective-electrode-with-moo2-microspheres-as-ion-to-electron-transducer
#3
Xianzhong Zeng, Wei Qin
A solid-contact ion-selective electrode (SC-ISE) for potassium with MoO2 microspheres as ion-to-electron transducer is described. MoO2 microsphers can be synthesized via the reduction of MoO3 nanobelts in an isopropanol solvent with a mild process, and the obtained MoO2 microspheres have been characterized by X-ray diffraction and field-emission scanning electron microscopy. With the application of MoO2 microspheres, the newly fabricated SC-ISE for K(+) exhibits a stable and rapid potential response. A near Nernstian slope of 55 mV/decade to potassium activities in the range of 10(-5) ‒ 10(-3) M is found and the detection limit is 10(-5...
August 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28734206/theoretical-investigation-of-the-conformational-space-of-baicalin
#4
Juan J Martínez Medina, Evelina G Ferrer, Patricia A M Williams, Nora B Okulik
Flavonoids are a large group of polyphenolic compounds ubiquitously present in plants. They are important components of human diet. They are recognized as potential drug candidates to be used in the treatment and prevention of a lot of pathological disorders, due to their protective effects. Baicalin (7-glucuronic acid 5, 6-dihydroxyflavone) is one of the main single active constituents isolated from the dried roots of Scutellaria baicalensis Georgi. The great interest on this flavonoid is due to its various pharmacological properties, such as antioxidant, antimicrobial, anti-inflammatory, anticancer and so on, and its high accumulation in the roots of S...
July 11, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28734165/rhodamine-spirolactam-sensors-operated-by-sulfur-cooperated-metal-complexation
#5
Gisuk Heo, Dahye Lee, Chi Gwan Kim, Jung Yun Do
New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu(2+) and Hg(2+). A sensor carrying a dithiocarbonate group responded selectively to Hg(2+) showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 10(4)...
July 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28733680/cid-fragmentation-h-d-exchange-and-supermetallization-of-barnase-barstar-complex
#6
Yury Kostyukevich, Aleksej A Shulga, Alexey Kononikhin, Igor Popov, Eugene Nikolaev, Sergey Deyev
The barnase-barstar complex is one of the most stable protein-protein complexes and has a very wide range of possible applications. Here we report the use of top-down mass spectrometry for the investigation of the structure of this complex, its ionization via ESI, isolation and fragmentation. It was found that the asymmetry of the resulting charge state distributions of the protein monomer product ions increased as the charge state of the precursor ions increased. For the investigation of the 3D structure of the complex, the gas phase H/D exchange reaction was used...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28733144/the-spliceosome-a-protein-directed-metalloribozyme
#7
REVIEW
Yigong Shi
Pre-mRNA splicing is executed by the ribonucleoprotein machinery spliceosome. Nearly forty years after the discovery of pre-mRNA splicing, the atomic structure of the spliceosome has finally come to light. Four distinct conformational states of the yeast spliceosome have been captured at atomic or near-atomic resolutions. Two catalytic metal ions at the active site are specifically coordinated by the U6 small nuclear RNA (snRNA) and catalyze both the branching reaction and the exon ligation. Of the three snRNAs in the fully-assembled spliceosome, U5 and U6, along with 30 contiguous nucleotides of U2 at its 5'-end, remain structurally rigid throughout the splicing reaction...
July 18, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28733029/synthesis-of-ni-ii-cu-ii-and-co-ii-complexes-with-new-macrocyclic-schiff-base-ligands-containing-dihydrazide-moiety-spectroscopic-structural-antimicrobial-and-antioxidant-properties
#8
Parveez Gull, Bandar A Babgi, Athar Adil Hashmi
In this study, the macrocyclic Schiff base ligand (L) derived from 1, 4-dicarbonyl-phenyl-dihydrazide and glyoxal (2:2) and its Ni (II), Cu (II) and Co(II) complexes were synthesised and were characterised by elemental analyses, FTIR, UV-Vis., mass and (1)H NMR. The ligand (L) behaves as a tetradentate ligand and coordinates to the metal ions via the nitrogen atoms and the complexes have the mononuclear structures. The synthesised compounds were evaluated for their inhibition potential against bacterial and fungal strains and the assay indicated that the metal complexes exhibited a remarkable antibacterial and antifungal activity against these tested strains...
July 18, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28733018/sono-assisted-preparation-of-bio-nanocomposite-for-removal-of-pb-2-ions-study-of-morphology-thermal-and-wettability-properties
#9
Shadpour Mallakpour, Vajiheh Behranvand
Multi-walled carbon nanotubes (MWCNT) loaded poly(ethylene terephthalate) (PET) composites, with different CNT contents, were fabricated through an ultrasound assisted method as a fast and green way. Then, the obtained composites were fully characterized via FT-IR, UV-Vis, XRD, TGA, FE-SEM and TEM, etc. For this purpose, PET bottle was recycled and applied as matrix of nanocomposites (NC)s. Then, we dispersed the covalent functionalization of MWCNTs with a protein dispersant and obtained a powder of protein-functionalized CNTs...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28733004/study-on-thermal-mechanical-and-adsorption-properties-of-amine-functionalized-mcm-41-pmma-and-mcm-41-ps-nanocomposites-prepared-by-ultrasonic-irradiation
#10
Gholamhossein Mohammadnezhad, Saeed Abad, Roozbeh Soltani, Mohammad Dinari
In this study, two common industrial polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), were incorporated into amine-functionalized MCM-41 mesoporous silica as reinforcement agents via an ultrasonic assisted method as a facile, fast, eco-friendly, and versatile synthetic tool. Amino functionalization of MCM-41 were performed by 3-aminopropyl triethoxysilane as a coupling agent and it is denoted as APTS-MCM-41. The obtained nanocomposites (NCs), APTS-MCM-41/PMMA and APTS-MCM-41/PS, were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), and thermogravimetric analysis (TGA)...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28732965/facile-and-cost-effective-preparation-of-pva-modified-calcium-carbonate-nanocomposites-via-ultrasonic-irradiation-application-in-adsorption-of-heavy-metal-and-oxygen-permeation-property
#11
Shadpour Mallakpour, Elham Khadem
This work is focused on the fabrication and determination of physicochemical behaviors of new poly(vinyl alcohol) (PVA) nanocomposites (NCs) containing various contents of calcium carbonate (CC) nanoparticles modified with γ-aminopropyl triethoxy silane (ATS) (henceforth designated as CC-ATS) which could be a crucial treatment for their application as gas barrier to O2 gas and uptake of metal ions in waste waters. Samples were produced through the solution casting method under ultrasound irradiation. Thermal and mechanical performances were also evaluated for all ultrasonically synthesized nanocomposites and the results indicated that thermal and mechanical stability are dramatically enhanced by addition of a small amount of modified CC-ATS within PVA up to 5wt% and higher amounts has low effect on the composite properties...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28732963/ultrasonic-assisted-synthesis-of-znte-nanostructures-and-their-structural-electrochemical-and-photoelectrical-properties
#12
P Ilanchezhiyan, G Mohan Kumar, Fu Xiao, S Poongothai, A Madhan Kumar, C Siva, Sh U Yuldashev, D J Lee, Y H Kwon, T W Kang
Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO2 traces in ZnTe through the corresponding vibrations...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28732346/multiplexed-aptasensor-for-simultaneous-detection-of-carcinoembryonic-antigen-and-mucin-1-based-on-metal-ion-electrochemical-labels-and-ru-nh3-6-3-electronic-wires
#13
Chao Ma, Haiyun Liu, Lina Zhang, Hao Li, Mei Yan, Xianrang Song, Jinghua Yu
In this paper, a dual-target electrochemical aptasensor has been developed for simultaneous detection of carcinoembryonic antigen and mucin-1 based on metal ion electrochemical labels and Ru(NH3)6(3+) electronic wires. When targets are present, the interaction between targets and their respective aptamers leads to the dissociation of double-strand DNA because the targets have higher affinity to its aptamer than the complementary strand. And the qualitative and quantitative analyses of the two targets are realized by the differential pulse voltammetry (DPV) peaks generated by metal ion electrochemical labels...
July 13, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28732297/influence-of-environmental-conditions-on-the-toxicokinetics-of-cadmium-in-the-marine-copepod-acartia-tonsa
#14
Maria D Pavlaki, Rui G Morgado, Cornelis A M van Gestel, Ricardo Calado, Amadeu M V M Soares, Susana Loureiro
mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity...
July 18, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28732169/design-of-modular-peptide-surfactants-and-their-surface-activity
#15
Hao-Fei Wang, David Wibowo, Zhengzhong Shao, Anton Peter J Middelberg, Chun-Xia Zhao
Designed peptide surfactants offer a number of advanced properties over conventional petrochemical surfactants, including biocompatibility, sustainability, and tailorability of the chemical and physical properties through peptide design. Their biocompatibility and degradability make them attractive for various applications, particularly for food and pharmaceutical applications. In this work, two new peptide surfactants derived from an amphiphilic peptide surfactant (AM1) were designed (AM-S and C8-AM) to better understand links between structure, interfacial activity and emulsification...
July 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28731690/the-metal-drives-the-chemistry-dual-functions-of-acireductone-dioxygenase
#16
Aditi R Deshpande, Thomas C Pochapsky, Dagmar Ringe
Acireductone dioxygenase (ARD) from the methionine salvage pathway (MSP) is a unique enzyme that exhibits dual chemistry determined solely by the identity of the divalent transition-metal ion (Fe(2+) or Ni(2+)) in the active site. The Fe(2+)-containing isozyme catalyzes the on-pathway reaction using substrates 1,2-dihydroxy-3-keto-5-methylthiopent-1-ene (acireductone) and dioxygen to generate formate and the ketoacid precursor of methionine, 2-keto-4-methylthiobutyrate, whereas the Ni(2+)-containing isozyme catalyzes an off-pathway shunt with the same substrates, generating methylthiopropionate, carbon monoxide, and formate...
July 21, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28731687/intramolecular-c-h-and-c-f-bond-oxygenation-by-site-differentiated-tetranuclear-manganese-models-of-the-oec
#17
Kurtis M Carsch, Graham de Ruiter, Theodor Agapie
The dangler manganese center in the oxygen-evolving complex (OEC) of photosystem II plays an important role in the oxidation of water to dioxygen. Inspired by the structure of the OEC, we synthesized a series of site-differentiated tetra-manganese clusters [LMn3(PhPz)3OMn][OTf]x (2: x = 2; 3: x = 1) that features an apical manganese ion-distinct from the others-that is appended to a trinuclear manganese core through an μ4-oxygen atom bridge. This cluster design was targeted to facilitate studies of high-valent Mn-oxo formation, which is a proposed step in the mechanism for water oxidation by the OEC...
July 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28731678/stable-and-efficient-cuo-based-photocathode-through-oxygen-rich-composition-and-au-pd-nanostructure-incorporation-for-solar-hydrogen-production
#18
Saeid Masudy-Panah, Roozbeh Siavash Moakhar, Chin Sheng Chua, Ajay Kumar Kushwaha, Goutam Kumar Dalapati
Enhancing stability against photo-corrosion and improving photocurrent response are the main challenges toward the development of cupric oxide (CuO) based photocathodes for solar-driven hydrogen production. In this paper, stable and efficient CuO-photocathodes have been developed using in-situ materials engineering and through gold-palladium (Au-Pd) nanoparticles deposition on the CuO surface. The CuO photocathode exhibits a photocurrent generation of ~3 mA/cm2 at 0V v/s RHE. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis and X-ray spectroscopy (XPS) confirm the formation of oxygen-rich (O-rich) CuO film which demonstrate highly stable photocathode with retained photocurrent of ~90% for 20 minutes...
July 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28731318/ultrafast-ionic-liquid-assisted-microwave-synthesis-of-sno-microflowers-and-their-superior-sodium-ion-storage-performance
#19
Bingsheng Qin, Huang Zhang, Thomas Diemant, Dorin Geiger, Rinaldo Raccichini, R Jürgen Behm, Ute Kaiser, Alberto Varzi, Stefano Passerini
Tin oxide (SnO) is considered one of the most promising metal oxides for utilization as anode material in sodium ion batteries (SIBs), due to its ease of synthesis, high specific gravimetric capacity and satisfactory cycling performance. However, to aim at practical applications, the coulombic efficiency during cycling needs to be further improved, which requires a deeper knowledge of its working mechanism. Here, a microflower-shaped SnO material is synthesized by means of an ultrafast ionic liquid-assisted microwave method...
July 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28731308/lead-toxicity-in-plants
#20
Hendrik Küpper
This review looks critically at the relevance of lead (Pb2+) toxicity and proposed mechanisms of Pb2+ -induced stress in algae and higher plants. As a basis, the current main sources of Pb2+ contamination in the environment are presented, which include agriculture, industry, and road traffic. Further, bioavailability of lead is discussed as a basis for evaluating the environmental relevance of the many studies on lead toxicity that have been published in the past decades. These studies suggest three main mechanisms of toxicity of Pb2+: inhibition of photosynthesis, oxidative stress, and "genotoxicity" including DNA damage and defects in mitosis...
April 10, 2017: Metal Ions in Life Sciences
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