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https://www.readbyqxmd.com/read/28550607/dft-based-prediction-of-reactivity-of-short-chain-alcohol-dehydrogenase
#1
I Stawoska, A Dudzik, M Wasylewski, M Jemioła-Rzemińska, A Skoczowski, K Strzałka, M Szaleniec
The reaction mechanism of ketone reduction by short chain dehydrogenase/reductase, (S)-1-phenylethanol dehydrogenase from Aromatoleum aromaticum, was studied with DFT methods using cluster model approach. The characteristics of the hydride transfer process were investigated based on reaction of acetophenone and its eight structural analogues. The results confirmed previously suggested concomitant transfer of hydride from NADH to carbonyl C atom of the substrate with proton transfer from Tyr to carbonyl O atom...
May 26, 2017: Journal of Computer-aided Molecular Design
https://www.readbyqxmd.com/read/28543941/evidence-of-structure-sensitivity-in-the-fischer-tropsch-reaction-on-model-cobalt-nanoparticles-by-time-resolved-chemical-transient-kinetics
#2
Walter T Ralston, Gérôme Melaet, Tommy Saephan, Gabor A Somorjai
The Fischer-Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer-Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non-steady-state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H2 /CO=2...
May 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28542471/biodegradation-of-di-n-butyl-phthalate-by-bacterial-consortium-lv-1-enriched-from-river-sludge
#3
Yangyang Wang, Fangfang Li, Xinling Ruan, Jian Song, Lv Lv, Liyuan Chai, Zhihui Yang, Lin Luo
A stable bacterial consortium (LV-1) capable of degrading di-n-butyl phthalate (DBP) was enriched from river sludge. Community analysis revealed that the main families of LV-1 are Brucellaceae (62.78%) and Sinobacteraceae (14.83%), and the main genera of LV-1 are Brucella spp. (62.78%) and Sinobacter spp. (14.83%). The optimal pH and temperature for LV-1 to degrade DBP were pH 6.0 and 30°C, respectively. Inoculum size influenced the degradation ratio when the incubation time was < 24 h. The initial concentration of DBP also influenced the degradation rates of DBP by LV-1, and the degradation rates ranged from 69...
2017: PloS One
https://www.readbyqxmd.com/read/28536198/understanding-the-essential-proton-pumping-kinetic-gates-and-decoupling-mutations-in-cytochrome-c-oxidase
#4
Ruibin Liang, Jessica M J Swanson, Mårten Wikström, Gregory A Voth
Cytochrome c oxidase (CcO) catalyzes the reduction of oxygen to water and uses the released free energy to pump protons against the transmembrane proton gradient. To better understand the proton-pumping mechanism of the wild-type (WT) CcO, much attention has been given to the mutation of amino acid residues along the proton translocating D-channel that impair, and sometimes decouple, proton pumping from the chemical catalysis. Although their influence has been clearly demonstrated experimentally, the underlying molecular mechanisms of these mutants remain unknown...
May 23, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28532786/fluxomic-evidence-for-impaired-contribution-of-short-chain-acyl-coa-dehydrogenase-to-mitochondrial-palmitate-%C3%AE-oxidation-in-symptomatic-patients-with-acads-gene-susceptibility-variants
#5
Anne-Frédérique Dessein, Monique Fontaine, Marie Joncquel Chevalier Curt, Gilbert Briand, Claire Sechter, Karine Mention-Mulliez, Dries Dobbelaere, Claire Douillard, Arnaud Lacour, Isabelle Redonnet-Vernhet, Delphine Lamireau, Magalie Barth, Marie-Christine Minot-Myhié, Alice Kuster, Pascale de Lonlay, Niels Gregersen, Cécile Acquaviva, Christine Vianey-Saban, Joseph Vamecq
BACKGROUND: Despite ACADS (acyl-CoA dehydrogenase, short-chain) gene susceptibility variants (c.511C>T and c.625G>A) are considered to be non-pathogenic, encoded proteins are known to exhibit altered kinetics. Whether or not, they might affect overall fatty acid β-oxidation still remains, however, unclear. METHODS: De novo biosynthesis of acylcarnitines by whole blood samples incubated with deuterated palmitate (16-(2)H3,15-(2)H2-palmitate) is suitable as a fluxomic exploration to distinguish between normal and disrupted β-oxidation, abnormal profiles and ratios of acylcarnitines with different chain-lengths being indicative of the site for enzymatic blockade...
May 19, 2017: Clinica Chimica Acta; International Journal of Clinical Chemistry
https://www.readbyqxmd.com/read/28516268/gpna-inhibits-the-sodium-independent-transport-system-l-for-neutral-amino-acids
#6
Martina Chiu, Cosimo Sabino, Giuseppe Taurino, Massimiliano G Bianchi, Roberta Andreoli, Nicola Giuliani, Ovidio Bussolati
L-γ-Glutamyl-p-nitroanilide (GPNA) is widely used to inhibit the glutamine transporter ASCT2, although it is known that it also inhibits other sodium-dependent amino acid transporters. In a panel of human cancer cell lines, which express the system L transporters LAT1 and LAT2, GPNA inhibits the sodium-independent influx of leucine and glutamine. The kinetics of the effect suggests that GPNA is a low affinity, competitive inhibitor of system L transporters. In Hs683 human oligodendroglioma cells, the incubation in the presence of GPNA, but not ASCT2 silencing, lowers the cell content of leucine...
May 17, 2017: Amino Acids
https://www.readbyqxmd.com/read/28515974/the-effect-of-fatigue-on-upper-quarter-y-balance-test-scores-in-recreational-weightlifters-a-randomized-controlled-trial
#7
Trenton D Salo, Eric Chaconas
BACKGROUND: A paucity of research currently exists for upper extremity return to sport testing. The Upper Quarter Y-Balance Test (YBT-UQ) is a clinical test of closed kinetic chain performance with demonstrated reliability. Prior investigations of the YBT-UQ were conducted with individuals in a resting state and no comparison to performance in a fatigued state has been conducted. PURPOSE: To examine the effect of upper extremity fatigue on the performance of the YBT-UQ in recreational weightlifters...
April 2017: International Journal of Sports Physical Therapy
https://www.readbyqxmd.com/read/28514168/regioselective-carbyne-transfer-to-ring-opening-alkyne-metathesis-initiators-gives-access-to-telechelic-polymers
#8
Stephen von Kugelgen, Renee Sifri, Donatela Bellone, Felix R Fischer
Regioselective carbyne-transfer reagents derived from (3,3,3-trifluoroprop-1-yn-1-yl)benzene give access to functionalized ring-opening alkyne metathesis polymerization (ROAMP) initiators [R-C6H4C≡Mo(OC(CH3)(CF3)2)3] featuring electron-donating or -withdrawing substituents on the benzylidyne. Kinetic studies and linear free-energy relationships reveal that the initiation step of the ring-opening alkyne metathesis polymerization of 5,6,11,12-tetradehydrobenzo[a,e][8]annulene exhibits a moderate positive Hammett reaction constant (ρ = +0...
May 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28510460/effects-of-membrane-defects-and-polymer-hydrophobicity-on-networking-kinetics-of-vesicles
#9
Yan Xia, Hyun-Sook Jang, Zhiqiang Shen, Geoffrey D Bothun, Ying Li, Mu-Ping Nieh
The kinetics of clustering unilamellar vesicles induced by inverse Pluronics, poly(propylene oxide)m-poly(ethylene oxide)n-poly(propylene oxide)m, POm-EOn-POm, were investigated via experiments and molecular dynamic simulations. Two important factors for controlling the networking kinetics are the membrane defects presumably located at the interfacial region between two lipid domains induced by acyl chain mismatch, and the polymer hydrophobicity. As expected, the clustering rate increases significantly with increasing bilayer defects on the membrane where the insertion of PPO is likely to take place because of the reduced energy barrier for the insertion of PO...
May 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28504414/high-molecular-weight-polynucleotides-by-transferase-catalyzed-living-chain-growth-polycondensation
#10
Lei Tang, Luis A Navarro, Ashutosh Chilkoti, Stefan Zauscher
We present terminal deoxynucleotidyl transferase-catalyzed enzymatic polymerization (TcEP) for the template-free synthesis of high-molecular-weight, single-stranded DNA (ssDNA) and demonstrate that it proceeds by a living chain-growth polycondensation mechanism. We show that the molecular weight of the reaction products is nearly monodisperse, and can be manipulated by the feed ratio of nucleotide (monomer) to oligonucleotide (initiator), as typically observed for living polymerization reactions. Understanding the synthesis mechanism and the reaction kinetics enables the rational, template-free synthesis of ssDNA that can be used for a range of biomedical and nanotechnology applications...
May 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28504183/enzymic-degradation-of-hydroxyethyl-cellulose-and-analysis-of-the-substitution-pattern-along-the-polysaccharide-chain
#11
Yongfu Diao, Mingwei Song, Yulin Zhang, Lin-Ying Shi, Yusan Lv, Rong Ran
The enzymatic degradation behavior of hydroxyethyl cellulose (HEC) samples with different molar substitutions (MS) values was investigated. The changes in the molecular structure of HEC treated with enzymatic approach in comparison to the native HEC were studied through nuclear magnetic resonance (NMR), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques and kinetics of degradation was studied by viscometry. The cleavage of HEC chains could be observed from FTIR and kinetics results...
August 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28504134/morphology-transport-characteristics-and-viscoelastic-polymer-chain-confinement-in-nanocomposites-based-on-thermoplastic-potato-starch-and-cellulose-nanofibers-from-pineapple-leaf
#12
Preetha Balakrishnan, M S Sreekala, Matjaž Kunaver, Miroslav Huskić, Sabu Thomas
Eco-friendly "green" nano composites were fabricated from potato starch and cellulose nanofibers from pineapple leaf. Nanocomposites of starch/cellulose nanofibers were prepared by solution mixing followed by casting. The investigation of the viscoelastic properties confirms starch macromolecular chain confinement around the nano scale cellulose surface, superior dispersion and very good interaction between thermoplastic starch and cellulose nanofibers. The degree of chain confinement was quantified. The chain confinement was associated with the immobilization of the starch macromolecular chains in the network formed by the nano-scale cellulose fibers as a result of hydrogen boding interactions...
August 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28503696/ion-induced-molecular-growth-in-clusters-of-small-hydrocarbon-chains
#13
Michael Gatchell, Rudy Delaunay, Giovanna D'Angelo, Arkadiusz Mika, Kostiantyn Kulyk, Alicja Domaracka, Patrick Rousseau, Henning Zettergren, Bernd A Huber, Henrik Cederquist
We report on studies of collisions between 3 keV Ar(+) projectile ions and neutral targets of isolated 1,3-butadiene (C4H6) molecules and cold, loosely bound clusters of these molecules. We identify molecular growth processes within the molecular clusters that appears to be driven by knockout processes and that could result in the formation of (aromatic) ring structures. These types of reactions are not unique to specific projectile ions and target molecules, but will occur whenever atoms or ions with suitable masses and kinetic energies collide with aggregates of matter, such as carbonaceous grains in the interstellar medium or aerosol nanoparticles in the atmosphere...
May 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28501450/exploring-prognosis-in-chronic-relapsing-visceral-leishmaniasis-among-hiv-infected-patients-circulating-leishmania-dna
#14
Gláucia Fernandes Cota, Marcos Roberto de Sousa, Tália Santana Machado de Assis, Bruna Fernandes Pinto, Ana Rabello
BACKGROUND: Visceral leishmaniasis (VL) affecting HIV-infected patients is considered a challenging condition because of its high mortality and relapse rates. The approach of this condition is still surrounded by many uncertainties, especially regarding the criteria to institute and discontinue secondary prophylaxis for VL. The aim of this study was to evaluate the Leishmania parasitism kinetic assessed by polymerase chain reaction (PCR) as a possible tool in the prognostic assessment in a context in which patients are receiving highly active antiretroviral therapy and secondary prophylaxis...
May 10, 2017: Acta Tropica
https://www.readbyqxmd.com/read/28500708/proteorhodopsin-photocycle-kinetics-between-ph-5-and-ph-9
#15
Thomas Köhler, Ingrid Weber, Clemens Glaubitz, Josef Wachtveitl
The retinal protein proteorhodopsin is a homolog of the well-characterized light-driven proton pump bacteriorhodopsin. Basic mechanisms of proton transport seem to be conserved, but there are noticeable differences in the pH ranges of proton transport. Proton transport and protonation state of a carboxylic acid side chain, the primary proton acceptor, are correlated. In case of proteorhodopsin, the pKa of the primary proton acceptor Asp-97 (pKa  ≈ 7.5) is unexpectedly close to environmental pH (pH ≈ 8)...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28498807/knockdown-of-pkm2-and-gls1-expression-can-significantly-reverse-oxaliplatin-resistance-in-colorectal-cancer-cells
#16
Wei-Qun Lu, Ying-Ying Hu, Xiao-Ping Lin, Wei Fan
Clinical treatment for colorectal cancer (CRC) thus far encounters a huge challenge due to oxaliplatin-resistance. As crucial rate-limiting enzymes in aerobic glycolysis and glutaminolysis, pyruvate kinase M2 type (PKM2) and kidney-type glutaminase (GLS1) are proposed to carry important implications in colorectal carcinogenesis and drug-resistance. This study aimed to explore the possible association of oxaliplatin-resistance with aerobic glycolysis/glutaminolysis indexed by PKM2/GLS1 expression. PKM2 and GLS1 expression was quantified by polymerase chain reaction (PCR) and Western blot techniques in CRC cell lines...
April 24, 2017: Oncotarget
https://www.readbyqxmd.com/read/28498385/polymer-brushes-based-on-plla-b-peo-colloids-for-the-preparation-of-protein-resistant-pla-surfaces
#17
E Mázl Chánová, O Pop-Georgievski, M M Kumorek, O Janoušková, L Machová, D Kubies, F Rypáček
In this study we investigate the formation of protein-resistant polymer surfaces, such as aliphatic polyesters, through the deposition of self-assemblies of amphiphilic poly(l-lactide)-b-poly(ethylene oxide), PLLA-b-PEO, copolymers as stable nanoparticles with a kinetically frozen PLLA core on model PLLA surfaces. The length of the PEO chains in the corona was tuned to achieve polymer brushes capable of preventing protein adsorption on PLA-based biomaterials. The spectroscopic ellipsometry, IR and XPS analysis, contact angle goniometry, and AFM proved that the PEO chains adopted a brush structure and were preferably exposed on the surface...
May 12, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/28498227/mechanisms-and-treatments-for-shoulder-injuries-in-overhead-throwing-athletes
#18
Jason L Zaremski, Joseph G Wasser, Heather K Vincent
Shoulder injuries in overhead throwing athletes are very common. Throwing volume and mechanical forces that are placed on the glenohumeral joint and associated soft tissue structures are contributors. Poor biomechanics and weak links in the kinetic chain place this athletic population at increased risk for shoulder injuries. Common biomechanical deficiencies in overhead throwing athletes typically involve poor sequential timing of muscle activity and insufficient coordination also presented in shoulder elevation and other functional tasks...
May 2017: Current Sports Medicine Reports
https://www.readbyqxmd.com/read/28497135/unscrambling-micro-solvation-of-cooh-and-nh-groups-in-neat-dimethyl-sulfoxide-insights-from-1-h-nmr-spectroscopy-and-computational-studies
#19
Panteleimon G Takis, Konstantinos D Papavasileiou, Loukas D Peristeras, Georgios C Boulougouris, Vasilios S Melissas, Anastassios N Troganis
Dimethyl sulfoxide (DMSO) has a significant, multi-faceted role in medicine, pharmacy, and biology as well as in biophysical chemistry and catalysis. Its physical properties and impact on biomolecular structures still attract major scientific interest, especially the interactions of DMSO with biomolecular functional groups. In the present study, we shed light on the "isolated" carboxylic (-COOH) and amide (-NH) interactions in neat DMSO via(1)H NMR studies along with extensive theoretical approaches, i.e. molecular dynamics (MD) simulations, density functional theory (DFT), and ab initio calculations, applied on model compounds (i...
May 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28494952/fast-protein-translation-can-promote-co-and%C3%A2-posttranslational-folding-of-misfolding-prone-proteins
#20
Fabio Trovato, Edward P O'Brien
Chemical kinetic modeling has previously been used to predict that fast-translating codons can enhance cotranslational protein folding by helping to avoid misfolded intermediates. Consistent with this prediction, protein aggregation in yeast and worms was observed to increase when translation was globally slowed down, possibly due to increased cotranslational misfolding. Observation of similar behavior in molecular simulations would confirm predictions from the simpler chemical kinetic model and provide a molecular perspective on cotranslational folding, misfolding, and the impact of translation speed on these processes...
May 9, 2017: Biophysical Journal
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