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molecular dynamics

Armando Jerome de Jesus, Hang Yin
Computer simulations have become an indispensable tool in studying molecular biological systems. The unmatched spatial and temporal resolution that it offers enables for microscopic-level views into the dynamics and mechanics of biological systems. Recent advances in hardware resources have also opened up to computer simulations the investigation of longer timescale biological processes and larger systems. The study of membrane proteins or peptides especially benefits from simulations due to difficulties related to crystallization of such proteins in a membrane environment...
2017: Methods in Molecular Biology
Henrique F Carvalho, Arménio J M Barbosa, Ana C A Roque, Olga Iranzo, Ricardo J F Branco
Recent advances in de novo protein design have gained considerable insight from the intrinsic dynamics of proteins, based on the integration of molecular dynamics simulations protocols on the state-of-the-art de novo protein design protocols used nowadays. With this protocol we illustrate how to set up and run a molecular dynamics simulation followed by a functional protein dynamics analysis. New users will be introduced to some useful open-source computational tools, including the GROMACS molecular dynamics simulation software package and ProDy for protein structural dynamics analysis...
2017: Methods in Molecular Biology
Yawei Tang, Xingquan Zeng, Yulin Wang, Lijun Bai, Qijun Xu, Zexiu Wei, Hongjun Yuan, Tashi Nyima
Hulless barley, with its unique nutritional value and potential health benefits, has increasingly attracted attentions in recent years. However, the transcription dynamics during hulless barley grain development is not well understood. In the present study, we investigated the transcriptome changes during barley grain development using Illumina paired-end RNA-sequencing. Two datasets of the developing grain transcriptomes from two barley landraces with the differential seed starch synthesis traits were generated, and comparative transcriptome approach in both genotypes was performed...
December 2, 2016: Functional & Integrative Genomics
Tiago N Cordeiro, Po-Chia Chen, Alfredo De Biasio, Nathalie Sibille, Francisco J Blanco, Jochen S Hub, Ramon Crehuet, Pau Bernadó
The intrinsically disordered p15(PAF) regulates DNA replication and repair when interacting with the Proliferating Cell Nuclear Antigen (PCNA) sliding clamp. As many interactions between disordered proteins and globular partners involved in signaling and regulation, the complex between p15(PAF) and trimeric PCNA is of low affinity, forming a transient complex that is difficult to characterize at a structural level due to its inherent polydispersity. We have determined the structure, conformational fluctuations, and relative population of the five species that coexist in solution by combining small-angle X-ray scattering (SAXS) with molecular modelling...
December 1, 2016: Nucleic Acids Research
Elizabeth Middleton, Matthew T Rondina
Sepsis is a dynamic, acute, infectious disease syndrome characterized by dysregulated thrombo-inflammatory responses. The high mortality associated with sepsis has been recognized since the earliest clinicians' writings. Despite this, advances in the treatment of sepsis have been more modest. This is limited, in part, by the heterogeneity in the definition, population, presentation, and causal factors of infectious syndromes. Given the persistently high morbidity and mortality associated with sepsis, a better understanding of the dysregulated cellular biology underpinning sepsis is needed...
December 2, 2016: Hematology—the Education Program of the American Society of Hematology
Rajesh Kumar Kar, Hungyo Kharerin, Ranjith Padinhateeri, Paike Jayadeva Bhat
Gal3p is an allosteric monomeric protein which activates the GAL genetic switch of Saccharomyces cerevisiae in response to galactose. Expression of constitutive mutant of Gal3p or overexpression of wild-type Gal3p activates the GAL switch in the absence of galactose. These data suggest that Gal3p exists as an ensemble of active and inactive conformations. Structural data has indicated that Gal3p exists in open (inactive) and closed (active) conformations. However, mutant of Gal3p that predominantly exists in inactive conformation and yet capable of responding to galactose has not been isolated...
November 29, 2016: Journal of Molecular Biology
AbdelKader A Metwally, Sherweit H El-Ahmady, Rania M Hathout
BACKGROUND: The normal fate of any natural product with a therapeutic potential is to be formulated into an effective medicine. However, the conventional methods of selecting the suitable formulations or carriers based on the formulator experiences, trials and errors as well as materials availability do not usually yield the optimal results. HYPOTHESIS: We hypothesize the possibility of the virtual optimum selection of a protein carrier for two polyphenolic compounds widely investigated for their chemopreventive effects; resveratrol and curcumin using a combination of some chemoinformatics tools...
December 15, 2016: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
Bhaswati Sengupta, Nilimesh Das, Pratik Sen
The local structural dynamics and denaturation profile of domain-III of HSA against guanidine hydrochloride (GnHCl) and temperature has been studied using a coumarin based solvatochromic fluorescent probe p-nitrophenyl coumarin ester (NPCE), covalently tagged to Tyr-411 residue. By the steady state, time-resolved and single molecular level fluorescence studies it has been established that the domain-III of HSA is very sensitive to GnHCl but somewhat resistant to temperature and the domain specific unfolding proceeds in an altered way as compared to the overall unfolding of HSA...
November 18, 2016: Biophysical Chemistry
Androulla Ioannou, Alexandra Lambrou, Vangelis Daskalakis, Eftychia Pinakoulaki
Myoglobin (Mb) is known to react slowly with nitirite to form the green pigment by NO2(-) cordination to the heme Fe in the O-binding nitrito (O1NO2) mode and to the heme 2-vinyl position. Nitrite is a powerful oxidizing agent and a biological reservoir for NO that has been implicated in a variety of aerobic biological systems. Accordingly, it is important to elucidate the nature and variety of NO2(-) reaction mechanisms with Mb. We have performed principal component analysis (PCA, or essential dynamics) on Molecular Dynamics trajectories of all MbNO2 coordination states to resolve the most important motions in the protein at 298K...
November 25, 2016: Biophysical Chemistry
Priya Maheshwari, D Dutta, T Muthulakshmi, B Chakraborty, N Raje, P K Pujari
The desorption mechanism of water from the hydrophilic mesopores of MCM-41 was studied using positron annihilation lifetime spectroscopy (PALS) and attenuated total reflection Fourier transform infrared spectroscopy supplemented with molecular dynamics (MD) simulation. PALS results indicated that water molecules do not undergo sequential evaporation in a simple layer-by-layer manner during desorption from MCM-41 mesopores. The results suggested that the water column inside the uniform cylindrical mesopore become stretched during desorption and induces cavitation (as seen in the case of ink-bottle type pores) inside it, keeping a dense water layer at the hydrophilic pore wall, as well as a water plug at both the open ends of the cylindrical pore, until the water was reduced to a certain volume fraction where the pore catastrophically empties...
December 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ankun Yang, Alexander J Hryn, Marc R Bourgeois, Won-Kyu Lee, Jingtian Hu, George C Schatz, Teri W Odom
Plasmonic nanostructures with enhanced localized optical fields as well as narrow linewidths have driven advances in numerous applications. However, the active engineering of ultranarrow resonances across the visible regime-and within a single system-has not yet been demonstrated. This paper describes how aluminum nanoparticle arrays embedded in an elastomeric slab may exhibit high-quality resonances with linewidths as narrow as 3 nm at wavelengths not accessible by conventional plasmonic materials. We exploited stretching to improve and tune simultaneously the optical response of as-fabricated nanoparticle arrays by shifting the diffraction mode relative to single-particle dipolar or quadrupolar resonances...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
Stephanie Voss, Dennis M Krüger, Oliver Koch, Yao-Wen Wu
Ras-like small GTPases function as molecular switches and regulate diverse cellular events. To examine the dynamics of signaling requires spatiotemporal visualization of their activity in the cell. Current small GTPase sensors rely on specific effector domains that are available for only a small number of GTPases and compete for endogenous regulator/effector binding. Here, we describe versatile conformational sensors for GTPase activity (COSGAs) based on the conserved GTPase fold. Conformational changes upon GDP/GTP exchange were directly observed in solution, on beads, and in live cells by Förster resonance energy transfer (FRET)...
November 29, 2016: Proceedings of the National Academy of Sciences of the United States of America
Ian Cook, Ting Wang, Mark Girvin, Thomas S Leyh
We are just beginning to understand the allosteric regulation of the human cytosolic sulfotransferase (SULTs) family-13 disease-relevant enzymes that regulate the activities of hundreds, if not thousands, of signaling small molecules. SULT1A1, the predominant isoform in adult liver, harbors two noninteracting allosteric sites, each of which binds a different molecular family: the catechins (naturally occurring flavonols) and nonsteroidal antiinflammatory drugs (NSAIDs). Here, we present the structure of an SULT allosteric binding site-the catechin-binding site of SULT1A1 bound to epigallocatechin gallate (EGCG)...
November 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
Daniel Mann, Christian Teuber, Stefan A Tennigkeit, Grit Schröter, Klaus Gerwert, Carsten Kötting
Heterotrimeric G proteins are crucial molecular switches that maintain a large number of physiological processes in cells. The signal is encoded into surface alterations of the Gα subunit that carries GTP in its active state and GDP in its inactive state. The ability of the Gα subunit to hydrolyze GTP is essential for signal termination. Regulator of G protein signaling (RGS) proteins accelerates this process. A key player in this catalyzed reaction is an arginine residue, Arg178 in Gαi1, which is already an intrinsic part of the catalytic center in Gα in contrast to small GTPases, at which the corresponding GTPase-activating protein (GAP) provides the arginine "finger...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
Kan Yue, Mingjun Huang, Ryan L Marson, Jinlin He, Jiahao Huang, Zhe Zhou, Jing Wang, Chang Liu, Xuesheng Yan, Kan Wu, Zaihong Guo, Hao Liu, Wei Zhang, Peihong Ni, Chrys Wesdemiotis, Wen-Bin Zhang, Sharon C Glotzer, Stephen Z D Cheng
Frank-Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails...
November 28, 2016: Proceedings of the National Academy of Sciences of the United States of America
Andrew M Fry, Laura O'Regan, Jessica Montgomery, Rozita Adib, Richard Bayliss
The EMLs are a conserved family of microtubule-associated proteins (MAPs). The founding member was discovered in sea urchins as a 77-kDa polypeptide that co-purified with microtubules. This protein, termed EMAP for echinoderm MAP, was the major non-tubulin component present in purified microtubule preparations made from unfertilized sea urchin eggs [J. Cell Sci. (1993) 104: , 445-450; J. Cell Sci. (1987) 87: (Pt 1), 71-84]. Orthologues of EMAP were subsequently identified in other echinoderms, such as starfish and sand dollar, and then in more distant eukaryotes, including flies, worms and vertebrates, where the name of ELP or EML (both for EMAP-like protein) has been adopted [BMC Dev...
October 15, 2016: Biochemical Society Transactions
N V Lukasheva, D A Tolmachev, V M Nazarychev, J M Kenny, S V Lyulin
Specific intermolecular interactions, in particular H-bonding, have a strong influence on the structural, thermal and relaxation characteristics of polymers. We report here the results of molecular dynamics simulations of Nylon 6 which provides an excellent example for the investigation of such an influence. To demonstrate the effect of proper accounting for H-bonding on bulk polymer properties, the AMBER99sb force field is used with two different parametrization approaches leading to two different sets of partial atomic charges...
December 2, 2016: Soft Matter
Po-Jen Hsu, Kun-Lin Ho, Sheng-Hsien Lin, Jer-Lai Kuo
The potential energy surface (PES), structures and thermal properties of methanol clusters (MeOH)n with n = 8-15 were explored by replica-exchange molecular dynamics (REMD) simulations with an empirical model and refined using density functional theory (DFT) methods. For a given size, local minima structures were sampled from REMD trajectories and archived by a newly developed molecular database via a two-stage clustering algorithm (TSCA). Our TSCA utilizes both the topology of O-HO hydrogen bonding networks and the similarity of the shapes to filter out duplicates...
December 2, 2016: Physical Chemistry Chemical Physics: PCCP
Léo Garcia, Chloé Barraud, Cyril Picard, Jérôme Giraud, Elisabeth Charlaix, Benjamin Cross
We present a nano-rheometer based on the dynamic drainage flow between a sphere and a plane from bulk regime to highly confined regime. The instrument gives absolute measurements of the viscosity of simple liquids in both regimes. For complex fluids, the measurements involve the viscosity and the elastic modulus. The device operates on distances ranging over four orders of magnitude from 1 nm to 10 μm, bridging rheological properties from the macroscopic to the molecular scale. This allows to measure an hydrodynamic or visco-elastic boundary condition and to explore the causes of the boundary condition at the microscopic level...
November 2016: Review of Scientific Instruments
Marco Pagliai, Giordano Mancini, Ivan Carnimeo, Nicola De Mitri, Vincenzo Barone
The electronic absorption spectra of pyridine and nicotine in aqueous solution have been computed using a multistep approach. The computational protocol consists in studying the solute solvation with accurate molecular dynamics simulations, characterizing the hydrogen bond interactions, and calculating electronic transitions for a series of configurations extracted from the molecular dynamics trajectories with a polarizable QM/MM scheme based on the fluctuating charge model. Molecular dynamics simulations and electronic transition calculations have been performed on both pyridine and nicotine...
December 2, 2016: Journal of Computational Chemistry
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