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Jianchang Xu, Shuangqing Sun, Zhikun Wang, Shiyuan Peng, Songqing Hu, Lijuan Zhang
Dissipative particle dynamics (DPD) simulation is used to study the effect of pH on the morphological transition in micelles assembled from dirhamnolipids (diRLs), and analyze the pH-driven mechanism and influence factors of micellar surface patterns. At pH < 4.0, various multilayer structures with homogeneous surface patterns are observed, whereas diRLs can self-assemble into novel anisotropic morphologies with phase-separated surface patterns at pH > 7.4, such as patchy spherical micelles, rod-like micelles with helical surface patterns and a lamellar phase with anisotropic surface patterns...
March 22, 2018: Physical Chemistry Chemical Physics: PCCP
Aristeidis Papagiannopoulos, Maria Karayianni, Stergios Pispas, Aurel Radulescu
The complexation of lysozyme with aggregates from two triblock amphiphilic polyelectrolytes of the same blocks but different topologies and block molar masses, namely PS-b-SCPI-b-PEO and SCPI-b-PS-b-PEO, is investigated by scattering and spectroscopy methods. Light scattering reveals that the interaction with lysozyme causes shrinkage of the self-assembled nanoparticles in the case of the hydrophobic-polyelectrolyte-hydrophilic sequence. In the polyelectrolyte-hydrophobic-hydrophilic sequence, the opposite trend is observed...
March 22, 2018: Soft Matter
Soundhararajan Gopi, Suvadip Paul, Sayan Ranu, Athi N Naganathan
The inherent conflict between noncovalent interactions and the large conformational entropy of the polypeptide chain forces folding reactions and their mechanisms to deviate significantly from chemical reactions. Accordingly, measures of structure in the transition state ensemble (TSE) are strongly influenced by the underlying distributions of microscopic folding pathways that are challenging to discern experimentally. Here, we present a detailed analysis of 150,000 folding transition paths of five proteins at three different thermodynamic conditions from an experimentally consistent statistical mechanical model...
March 23, 2018: Journal of Physical Chemistry Letters
Izar Capel Berdiell, Stuart L Warriner, Malcolm A Halcrow
Silver(i) complexes of 2,4,6-tri(pyrazol-1-yl)pyridine (tpp), 2,4,6-tri(pyrazol-1-yl)pyrimidine (tpym), 2,4,6-tri(pyrazol-1-yl)-1,3,5-triazine (tpt) and 2,4-di(pyrazol-1-yl)-1,3,5-triazine (bpt) are reported. Dinuclear [Ag2(μ-tpp)2(MeCN)2][BF4]2·2MeCN and [Ag2(μ-tpym)2(MeCN)2][BF4]2 are formed from approximately planar [AgL(NCMe)]+ (L = tpp or bpym) centres, which dimerise via apical interactions to the pendant pyrazolyl donor on each ligand. Two polymeric solvatomorph phases [Ag2(μ-tpp)2][BF4]2·nMeNO2 were obtained by crystallising AgBF4 and tpp from nitromethane solution...
March 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Christine J Ye, Guo Liu, Henry H Heng
Genome chaos, or karyotype chaos, represents a powerful survival strategy for somatic cells under high levels of stress/selection. Since the genome context, not the gene content, encodes the genomic blueprint of the cell, stress-induced rapid and massive reorganization of genome topology functions as a very important mechanism for genome (karyotype) evolution. In recent years, the phenomenon of genome chaos has been confirmed by various sequencing efforts, and many different terms have been coined to describe different subtypes of the chaotic genome including "chromothripsis," "chromoplexy," and "structural mutations...
2018: Methods in Molecular Biology
Karina Jácome-López, Mayra Furlan-Magaril
The spatial organization of the chromatinized genome inside the cell nucleus impacts genomic function. In transcription, the hierarchical genome structure creates spatial regulatory landscapes, in which modulating elements like enhancers can contact their target genes and activate their expression, as a result of restricting their exploration to a specific topological neighbourhood. Here we describe exciting recent findings obtained through "C" technologies in pluripotent cells and early embryogenesis and emphasize some of the key unanswered questions arising from them...
2018: Methods in Molecular Biology
Adnane Aouidate, Adib Ghaleb, Mounir Ghamali, Samir Chtita, Abdellah Ousaa, M'barek Choukrad, Abdelouahid Sbai, Mohammed Bouachrine, Tahar Lakhlifi
BACKGROUND: Quantitative structure-activity relationship (QSAR) was carried out to study a series of aminooxadiazoles as PIM1 inhibitors having pki ranging from 5.59 to 9.62 (ki in nM). The present study was performed using Genetic Algorithm method of variable selection (GFA), multiple linear regression analysis (MLR) and non-linear multiple regression analysis (MNLR) to build unambiguous QSAR models of 34 substituted aminooxadiazoles toward PIM1 inhibitory activity based on topological descriptors...
March 22, 2018: Chemistry Central Journal
Rienk van Grondelle
Light induced charge and energy transport in nucleic acids and proteins is the basis of fundamental biological processes such as photosynthesis, vision, DNA-photostability, DNA-photodamage and photosensing. This article summarises the concluding remarks given at the Faraday Discussions meeting on this topic. The specific themes arising from the meeting that are discussed herein include charge transfer in nucleic acids and proteins, excited state dynamics and topology, vibrations and dynamic disorder, proteins and charge transfer states, nanobiophotonics coupled to biomedical applications and photosynthesis...
March 22, 2018: Faraday Discussions
Biao Zhou, Chao Sun, Deockhyeon Ahn, Youngok Kim
Passive tracking aims to track targets without assistant devices, that is, device-free targets. Passive tracking based on Radio Frequency (RF) Tomography in wireless sensor networks has recently been addressed as an emerging field. The passive tracking scheme using geometric theorems (GTs) is one of the most popular RF Tomography schemes, because the GT-based method can effectively mitigate the demand for a high density of wireless nodes. In the GT-based tracking scheme, the tracking scenario is considered as a two-dimensional geometric topology and then geometric theorems are applied to estimate crossing points (CPs) of the device-free target on line-of-sight links (LOSLs), which reveal the target's trajectory information in a discrete form...
March 17, 2018: Sensors
György Abrusán, Joseph A Marsh
It has been suggested that the evolution of protein complexes is significantly influenced by stochastic, non-adaptive processes. Using ligand binding as a proxy of function, we show that the structure of ligand-binding sites significantly influences the evolution of protein complexes. We show that homomers with multi-chain binding sites (MBSs) evolve new functions slower than monomers or other homomers, and those binding cofactors and metals have more conserved quaternary structure than other homomers. Moreover, the ligands and ligand-binding pockets of homologous MBS homomers are more similar than monomers and other homomers...
March 20, 2018: Cell Reports
Robert Gibbs, Gregory Moreton, Turgut Meydan, Paul Williams
The investigation of planar coils of differing topologies, when combined with a magnetostrictive amorphous ribbon to form a stress-sensitive self-inductor, is an active research area for applications as stress or pressure sensors. Four topologies of planar coil (Circular, Mesh, Meander, and Square) have been constructed using copper track on 30 mm wide PCB substrate. The coils are energized to draw 0.4 A and the resulting magnetic field distribution is observed with a newly developed three-dimensional magnetic field scanner...
March 21, 2018: Sensors
Luciana Romão, Vanessa P do Canto, Paulo A Netz, Vivaldo Moura-Neto, Ângelo C Pinto, Cristian Follmer
Glioblastoma multiform (GBM) is the most common and devastating type of primary brain tumor, being considered the deadliest of human cancers. In this context, extensive efforts have been undertaken to develop new drugs that exhibit both antiproliferation and antimetastasis effects on GBM. 1,4-Naphthoquinone (1,4-NQ) scaffold has been found in compounds able to inhibit important biological targets associated with cancer, which includes DNA topoisomerase, Hsp90 and monoamine oxidase. Among potential antineoplastic 1,4-NQs is the plant-derived lapachol (2-hydroxy-3-prenyl-1,4-naphthoquinone) that was found to be active against the Walker-256 carcinoma and Yoshida sarcoma...
March 20, 2018: Anti-cancer Drugs
Ming Zheng, Fang-Yuan Chen, Jia-Nan Tian, Qing-Jiang Pan
To provide deep insight into cation-cation interactions (CCIs) involving hexavalent actinyl species that are major components in spent nuclear fuel and pose important implications for the effective removal of radiotoxic pollutants in the environment, a series of homo- and heterobimetallic actinide complexes supported by cyclopentadienyl (Cp) and polypyrrolic macrocycle (H4 L) ligands were systematically investigated using relativistic density functional theory. The metal sort in both parts of (THF)(H2 L)(OAnVI O) and (An')III Cp3 from U to Np to Pu, as well as the substituent bonding to Cp from electron-donating Me to H to electron-withdrawing Cl, SiH3 , and SiMe3 , was changed...
March 21, 2018: Inorganic Chemistry
Sang-Yeon Hwang, Jaewook Kim, Woo Youn Kim
In theoretical charge-transfer research, calculation of the electronic coupling element is crucial for examining the degree of the electronic donor-acceptor interaction. The tunneling current (TC), representing the magnitudes and directions of electron flow, provides a way of evaluating electronic couplings, along with the ability of visualizing how electrons flow in systems. Here, we applied the TC theory to π-conjugated organic dimer systems, in the form of our fragment-orbital tunneling current (FOTC) method, which uses the frontier molecular-orbitals of system fragments as diabatic states...
March 21, 2018: Physical Chemistry Chemical Physics: PCCP
Peter C Burns, May Nyman
Uranyl peroxide clusters containing from 16 to 124 uranyl ions self-assemble in aqueous solution and exhibit tremendous topological complexity. Most of these clusters are cages, with the inside and outside surfaces passivated by oxygen atoms that are triply bonded to U(vi) cations (yl oxygen). It has become increasing apparent that the counter cations associated with these anionic cage clusters impact their assembly, topologies, and behavior in solution, including aggregation and aqueous solubility. Here we review the chemical compositions and topologies of uranyl peroxide clusters...
March 21, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Jiajie Peng, Xuanshuo Zhang, Weiwei Hui, Junya Lu, Qianqian Li, Shuhui Liu, Xuequn Shang
BACKGROUND: Gene Ontology (GO) is one of the most popular bioinformatics resources. In the past decade, Gene Ontology-based gene semantic similarity has been effectively used to model gene-to-gene interactions in multiple research areas. However, most existing semantic similarity approaches rely only on GO annotations and structure, or incorporate only local interactions in the co-functional network. This may lead to inaccurate GO-based similarity resulting from the incomplete GO topology structure and gene annotations...
March 19, 2018: BMC Systems Biology
Abdelilah Benallou, Habib El Alaoui El Abdallaoui, Hocine Garmes
The mechanism nature of the intramolecular Diels-Alder reaction has been performed; and thus, the changes of C-C bond forming/breaking along IRC are characterized in this study. Conceptual DFT analyses of the most favorable adduct fused/exo shows that the flux electronic will take place from diene to dienophile moiety. Moreover, ELF topological analysis based on the electron density predicts that C-C bond is formed by the coupling of two pseudoradical centers generated at the most significant atoms of the molecules...
February 2018: Heliyon
Sean D Workman, Liam J Worrall, Natalie C J Strynadka
Undecaprenyl pyrophosphate phosphatase (UppP) is an integral membrane protein that recycles the lipid carrier essential to the ongoing biosynthesis of the bacterial cell wall. Individual building blocks of peptidoglycan are assembled in the cytoplasm on undecaprenyl phosphate (C55-P) before being flipped to the periplasmic face, where they are polymerized and transferred to the existing cell wall sacculus, resulting in the side product undecaprenyl pyrophosphate (C55-PP). Interruption of UppP's regeneration of C55-P from C55-PP leads to the buildup of cell wall intermediates and cell lysis...
March 20, 2018: Nature Communications
Peyman Tavallali, Hana Koorehdavoudi, Joanna Krupa
Intrinsic Frequency (IF) has recently been introduced as an ample signal processing method for analyzing carotid and aortic pulse pressure tracings. The IF method has also been introduced as an effective approach for the analysis of cardiovascular system dynamics. The physiological significance, convergence and accuracy of the IF algorithm has been established in prior works. In this paper, we show that the IF method could be derived by appropriate mathematical approximations from the Navier-Stokes and elasticity equations...
March 20, 2018: Scientific Reports
Jason W Shapiro, Catherine Putonti
Bacteriophages are the most abundant and diverse biological entities on the planet, and new phage genomes are being discovered at a rapid pace. As more phage genomes are published, new methods are needed for placing these genomes in an ecological and evolutionary context. Phages are difficult to study by phylogenetic methods, because they exchange genes regularly, and no single gene is conserved across all phages. Here, we demonstrate how gene-level networks can provide a high-resolution view of phage genetic diversity and offer a novel perspective on virus ecology...
March 20, 2018: MBio
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