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https://www.readbyqxmd.com/read/28432454/cobalt-tetradehydrocorrins-coordinated-by-imidazolate-like-histidine-in-the-heme-pocket-of-horseradish-peroxidase
#1
Koji Oohora, Ning Tang, Yoshitsugu Morita, Takashi Hayashi
Horseradish peroxidase was reconstituted with cobalt tetradehydrocorrin, rHRP(Co(TDHC)), as a structural analog of cobalamin coordinated with an imidazolate-like His residue, which is generally seen in native enzymes. In contrast to the previously reported cobalt tetradehydrocorrin-reconstituted myoglobin, rMb(Co(TDHC)), the HRP matrix was expected to provide strong axial ligation by His170 which has imidazolate character. rHRP(Co(II)(TDHC)) was characterized by EPR and its reaction with reductants indicates a negative shift of its redox potential compared to rMb(Co(TDHC))...
April 21, 2017: Journal of Biological Inorganic Chemistry: JBIC
https://www.readbyqxmd.com/read/28430506/demonstration-of-multisetting-one-way-einstein-podolsky-rosen-steering-in-two-qubit-systems
#2
Ya Xiao, Xiang-Jun Ye, Kai Sun, Jin-Shi Xu, Chuan-Feng Li, Guang-Can Guo
Einstein-Podolsky-Rosen (EPR) steering describes the ability of one party to remotely affect another's state through local measurements. One of the most distinguishable properties of EPR steering is its asymmetric aspect. Steering can work in one direction but fail in the opposite direction. This type of one-way steering, which is different from the symmetry concepts of entanglement and Bell nonlocality, has garnered much interest. However, an experimental demonstration of genuine one-way EPR steering in the simplest scenario, i...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430068/caring-for-patients-or-organs-new-therapies-raise-new-dilemmas-in-the-emergency-department
#3
Arjun Prabhu, Lisa S Parker, Michael A DeVita
Two potentially lifesaving protocols, emergency preservation and resuscitation (EPR) and uncontrolled donation after circulatory determination of death (uDCDD), currently implemented in some U.S. emergency departments (EDs), have similar eligibility criteria and initial technical procedures, but critically different goals. Both follow unsuccessful cardiopulmonary resuscitation and induce hypothermia to "buy time": one in trauma patients suffering cardiac arrest, to enable surgical repair, and the other in patients who unexpectedly die in the ED, to enable organ donation...
May 2017: American Journal of Bioethics: AJOB
https://www.readbyqxmd.com/read/28429936/electron-decoupling-with-dynamic-nuclear-polarization-in-rotating-solids
#4
Edward P Saliba, Erika L Sesti, Faith J Scott, Brice J Albert, Eric J Choi, Nicholas Alaniva, Chukun Gao, Alexander B Barnes
Dynamic nuclear polarization (DNP) can enhance NMR sensitivity by orders of magnitude by transferring spin polarization from electron paramagnetic resonance (EPR) to NMR. However, paramagnetic DNP polarizing agents can have deleterious effects on NMR signals. Electron spin decoupling can mitigate these paramagnetic relaxation effects. We demonstrate electron decoupling experiments in conjunction with DNP and magic angle spinning (MAS) NMR spectroscopy. Following a DNP and spin diffusion period, the microwave irradiation frequency is quickly tuned on-resonance with electrons on the DNP polarizing agent...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28429421/a-boat-shaped-tetracationic-macrocycle-with-a-semiconducting-organic-framework
#5
Minh T Nguyen, Matthew D Krzyaniak, Magdalena Owczarek, Daniel P Ferris, Michael R Wasielewski, J Fraser Stoddart
We report the synthesis of a tetracationic macrocycle which contains two N,N'-bis(methylene)naphthalenediimide units inserted in between the pyridinium rings of the bipyridinium units in cyclobis(paraquat-p-phenylene) (CBPQT(4+) or "blue box") and describe the investigation of its potential use in materials for organic electronics. The incorporation of the two naphthalenediimide (NDI) units into the constitution of CBPQT(4+) , not only changes the supramolecular properties of the tetracation in the solid state, but also has a profound influence on the electrochemical and electronic behavior of the resulting tetracationic macrocycle...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28429253/modified-metformin-as-a-more-potent-anticancer-drug-mitochondrial-inhibition-redox-signaling-antiproliferative-effects-and-future-epr-studies
#6
Balaraman Kalyanaraman, Gang Cheng, Micael Hardy, Olivier Ouari, Adam Sikora, Jacek Zielonka, Michael B Dwinell
Metformin, one of the most widely prescribed antidiabetic drugs in the world, is being repurposed as a potential drug in cancer treatment. Epidemiological studies suggest that metformin exerts anticancer effects in diabetic patients with pancreatic cancer. However, at typical antidiabetic doses the bioavailability of metformin is presumably too low to exert antitumor effects. Thus, more potent analogs of metformin are needed in order to increase its anticancer efficacy. To this end, a new class of mitochondria-targeted metformin analogs (or mito-metformins) containing a positively-charged lipophilic triphenylphosphonium group was synthesized and tested for their antitumor efficacy in pancreatic cancer cells...
April 21, 2017: Cell Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28426929/exerting-enhanced-permeability-and-retention-effect-driven-delivery-by-ultrafine-iron-oxide-nanoparticles-with-t1-t2-switchable-magnetic-resonance-imaging-contrast
#7
Liya Wang, Jing Huang, Hongbo Chen, Hui Wu, Yaolin Xu, Yuancheng Li, Hong Yi, Yongqiang Andrew Wang, Lily Yang, Hui Mao
The poor delivery efficiency remains a major challenge in nanomaterial based tumor targeted imaging and drug delivery. This work demonstrated a strategy to improve nanoparticle delivery and intratumoral distribution using a sub-5 nm (3.5 nm core size) ultrafine iron oxide nanoparticles (uIONPs) that can easily extravasate from the tumor vasculature and readily diffuse into the tumor tissue compared to iron oxide nanoparticles (IONP) with larger sizes, followed by self-assembling in the acidic tumor interstitial space to limit their re-entering the circulation...
April 20, 2017: ACS Nano
https://www.readbyqxmd.com/read/28426213/role-of-mediator-and-effects-of-temperature-on-ortho-c-n-bond-fusion-reactions-of-aniline-using-ruthenium-templates-isolation-and-characterization-of-new-ruthenium-complexes-of-the-in-situ-generated-ligands
#8
Suman K Roy, Debabrata Sengupta, Santi Prasad Rath, Tanushri Saha, Subhas Samanta, Sreebrata Goswami
In this work, ortho-C-N bond fusion reactions of aniline are followed by the use of two different ruthenium mediators. Reaction of aniline with [Ru(III)(terpy)Cl3] (terpy = 2,2':6',2″-terpyridine) resulted in a trans bis-aniline ruthenium(II) complex [1](+) which upon oxidation with H2O2 produced compound [2](+) of a bidentate ligand, N-phenyl-1,2-benzoquinonediimine, due to an oxidative ortho-C-N bond fusion reaction. Complex [1](+) and aniline (neat) at 185 °C produced a bis-chelated ruthenium complex (3)...
April 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28426067/bioinspired-peptosomes-with-programmed-stimuli-responses-for-sequential-drug-release-and-high-performance-anticancer-therapy
#9
Yuan Li, Wei Li, Weier Bao, Bin Liu, Dan Li, Yumeng Jiang, Wei Wei, Fazheng Ren
Combination therapy with enhanced therapeutic and antimetastatic efficacy has become promising for cancer treatment. There is an urgent need to design a co-delivery system to sequentially release the drug pair at desired locations that can increase the intra-tumoral drug concentration and reduce the side effects. Inspired by virus architecture and function, herein, we developed a peptosome (PS)-based co-delivery system, PePm/PS/Curcumin (Cur), for the sequential release of the therapeutic peptide Pe and chemodrug Cur...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28426058/radical-cations-of-phenyl-silatrane
#10
Vitalijs Romanovs, Valery Sidorkin, Elena Belogolova, Viatcheslav Jouikov
Electrochemical oxidation of phenylsilatrane (1) in CH3CN/0.1 M Bu4NPF6 has been studied by voltammetry, UV-Vis and EPR-coupled spectroelectrochemistry supported by DFT calculations. One-electron withdrawal from the HOMO of 1, formed with a predominant contribution of the atrane N atom to the 3c-4e system, results in a short lived radical cation, in which the atrane nitrogen atom is almost planar and carries most of the spin density showing strong coupling with the protons of the axially directed C-H bonds of the three adjacent α-methylene groups (g = 2...
April 20, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28423212/persistent-radicals-of-self-assembled-benzophenone-bis-urea-macrocycles-characterization-and-application-as-a-polarizing-agent-for-solid-state-dnp-mas-spectroscopy
#11
Baillie A DeHaven, John T Tokarski, Arthur A Korous, Frederic Mentink-Vigier, Thomas M Makris, Alexander M Brugh, Malcolm D E Forbes, Johan van Tol, Clifford Russ Bowers, Linda S Shimizu
UV-irradiation of a self-assembled benzophenone bis-urea macrocycle generates μM amounts of radicals that persist for weeks under ambient conditions. High-Field EPR and variable temperature X-band EPR studies suggest a resonance stabilized radical pair through H-abstraction. These endogenous radicals were applied as a polarizing agent for magic angle spinning (MAS) dynamic nuclear polarization (DNP) NMR enhancement. The field-stepped DNP enhancement profile exhibits a sharp peak with a maximum enhancement of εon/off = 4 superimposed on a nearly constant DNP enhancement of εon/off = 2 over a broad field range...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422504/integrated-computational-approach-to-the-electron-paramagnetic-resonance-characterization-of-rigid-310-helical-peptides-with-toac-nitroxide-spin-labels
#12
Marco Gerolin, Mirco Zerbetto, Alessandro Moretto, Fernando Formaggio, Claudio Toniolo, Martin van Son, Maryam Hashemi Shabestari, Martina Huber, Paolo Calligari, Antonino Polimeno
We address the interpretation, via an integrated computational approach, of the experimental continuous-wave electron paramagnetic resonance (cw-EPR) spectra of a complete set of conformationally highly restricted, stable 310-helical peptides from hexa- to nonamers, each bis-labeled with nitroxide radical-containing TOAC (4-amino-1-oxyl-2,2,6,6-tetramethylpiperidine-4-carboxylic acid) residues. The usefulness of TOAC for this type of analysis has been shown already to be due to its cyclic piperidine side chain, which is rigidly connected to the peptide backbone α-carbon...
April 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28422481/gold-nanoparticles-induced-endothelial-leakiness-depends-on-particle-size-and-endothelial-cell-origin
#13
Magdiel I Setyawati, Chor Yong Tay, Boon Huat Bay, David T Leong
The endothelium presents a formidable barrier for cancer nanomedicine, as the intravenously introduced nanomedicine needs to leave the blood vessel at the tumor site. Endothelial permeability and retention effect (EPR) is not dependable since it is derived from tumors. Certain nanoparticles with specific characteristics are able to induce micrometer sized gaps between endothelial cells. This effect is called "nanoparticle induced endothelial leakiness" (NanoEL). NanoEL therefore allows the nanotechnology to control access to the tumor even in the absence of any EPR effect...
April 20, 2017: ACS Nano
https://www.readbyqxmd.com/read/28422350/electronic-g-tensors-in-u-v-complexes-a-computational-study
#14
Helen Moylan, Joseph McDouall
The theory and computation of EPR parameters from first principles has seen a great deal of development over the past two decades. In particular, various techniques for the computation of the electronic g tensor have been implemented in many quantum chemistry packages. These methods have been successfully applied to paramagnetic organic species and transition metal systems. The situation is less well-understood and established in the case of actinide containing molecules and there is a dearth of experimental data available for validation of computations...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422067/synthesis-characterization-antimicrobial-and-antiproliferative-activity-evaluation-of-cu-ii-co-ii-zn-ii-ni-ii-and-pt-ii-complexes-with-isoniazid-derived-compound
#15
Elena Pahonțu, Diana-Carolina Ilieș, Sergiu Shova, Camelia Oprean, Virgil Păunescu, Octavian Tudorel Olaru, Flavian Ștefan Rădulescu, Aurelian Gulea, Tudor Roșu, Doina Drăgănescu
Hydrazone complexes of Cu(II), Co(II), Zn(II), Ni(II) and Pt(II) with N-isonicotinoyl-N'-(3-metoxy-2 hydroxybenzaldehyde)-hydrazone (HL) were synthesized and characterized by different physico-chemical techniques including elemental and thermal analysis, magnetic susceptibility measurements, molar electric conductivity, as well as IR (infrared), ¹H-NMR and (13)C-NMR (hydrogen and carbon nuclear magnetic resonance, UV-Vis (ultraviolet-visible), FAB (fast atom bombardment), EPR (electron paramagnetic resonance), and mass spectroscopies...
April 19, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28419595/lipopolysaccharide-lps-binding-to-the-periplasmic-protein-lpta
#16
Kathryn M Schultz, Tanner J Lundquist, Candice S Klug
Lipopolysaccharide (LPS) and the periplasmic protein LptA are two essential components of Gram-negative bacteria. LPS, also known as endotoxin, is found asymmetrically distributed in the outer leaflet of the outer membrane of Gram-negative bacteria such as Escherichia coli and plays a role in the organism's natural defenses in adverse environmental conditions. LptA is a member of the lipopolysaccharide transport protein (Lpt) family, which also includes LptC, LptDE, and LptBFG2 , that functions to transport LPS through the periplasm to the outer leaflet of the outer membrane after MsbA flips LPS across the inner membrane...
April 17, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28418598/redox-disproportionation-of-a-decamethyltitanocene-iii-isonitrile-alkinyl-complex
#17
Torsten Beweries, Fabian Reiss, Dirk Hollmann, Haijun Jiao, Perdita Arndt, Anke Spannenberg, Uwe Rosenthal, Kai Altenburger
A mixed decamethyltitanocene(III) isonitrile alkinyl complex (7) was synthesised via sequential introduction of the isonitrile and alkinyl ligands. Direct synthesis results in the formation of the diamagnetic decamethyltitanocene bis(isonitrile) (2) and bis(alkinyl) (3) complexes. Compound 7 undergoes disproportionation to give 2 and 3. All complexes were fully characterised by IR, MS as well as by NMR and EPR, respectively. Molecular structures for complexes 2 and 7 are reported. The stability and reactivity of these complexes are rationalised by DFT computations...
April 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28415509/preparation-and-evaluation-of-a-novel-anticancer-drug-delivery-carrier-for-5-fluorouracil-using-synthetic-bola-amphiphile-based-on-lysine-as-polar-heads
#18
Beibei Hu, Yue Yuan, Yun Yan, Xiaoping Zhou, Yue Li, Qiming Kan, Sanming Li
A novel bolaamphiphile surfactant N,N'-(dodecane-1, 12-diyl) bis (2,6-diaminohexanamide) (DADL) was designed and synthesized using l-lysine and 1,12-diaminododecane as the hydrophilic and hydrophobic part, respectively. After separation and purification, the structure of the synthetic bolaamphiphile surfactant was verified by FTIR, MS and (1)H NMR. The synthetic bolaamphiphile was able to self-assemble to form vesicles. After formulation screening, vesicles loaded with 5-Fluorouracil (5-Fu) were prepared with Tween 60 and DADL by sonication and were examined by dynamic light scattering and transmission electron microscopy...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28414431/mononuclear-sulfido-tungsten-v-complexes-completing-the-tp-mexy-m-mo-w-e-o-s-series
#19
Stephen Sproules, Aston A Eagle, Graham N George, Jonathan M White, Charles G Young
Orange Tp*WSCl2 has been synthesized from the reactions of Tp*WOCl2 with boron sulfide in refluxing toluene or Tp*WS2Cl with PPh3 in dichloromethane at room temperature. Mononuclear sulfido-tungsten(V) complexes, Tp*WSXY {X = Y = Cl, OPh, SPh, SePh; X = Cl, Y = OPh; XY = toluene-3,4-dithiolate (tdt), quinoxaline-2,3-dithiolate (qdt); and Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate} were prepared by metathesis of Tp*WSCl2 with the respective alkali metal salt of X(-)/XY(2-), or [NHEt3]2(qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, and infrared (IR), electron paramagnetic resonance (EPR) and electronic absorption spectroscopies...
April 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28414428/low-temperature-trapping-of-intermediates-in-the-reaction-of-no-%C3%A2-with-o2
#20
Leila Mahmoudi, Reinhard Kissner, Willem H Koppenol
The autoxidation of NO(•) was studied in glass-like matrices of 2-methylbutane at 110 K and in a 8:3 v/v mixture of 2,2-dimethylbutane and n-pentane (rigisolve) at 80-90 K, by letting gaseous NO(•) diffuse into these solvents that were saturated with O2. In 2-methyllbutane, we observed a red compound. However, in rigisolve at 85-90 K, a bright yellow color appears that turns red when the sample is warmed by 10-20 K. The new yellow compound is a precursor of the red one and also diamagnetic. The UV-vis spectrum of the yellow compound contains a band which resembles that present in ONOO(-)...
April 17, 2017: Inorganic Chemistry
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