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https://www.readbyqxmd.com/read/28922608/j-si-h-coupling-constants-of-activated-si-h-bonds
#1
Petra Meixner, Kilian Batke, Andreas Fischer, Dominik Schmitz, Georg Eickerling, Marcel Kalter, Klaus Ruhland, Klaus Eichele, José E Barquera-Lozada, Nicola P M Casati, Fabio Montisci, Piero Macchi, Wolfgang Scherer
We outline in this combined experimental and theoretical NMR study that sign and magnitude of J(Si,H) coupling constants provide reliable indicators to evaluate the extent of the oxidative addition of Si-H bonds in hydrosilane complexes. In combination with experimental electron density studies and MO analyses a simple structure-property relationship emerges: positive J(Si,H) coupling constants are observed in cases where M → L π-back-donation (M = transition metal; L = hydrosilane ligand) dominates. The corresponding complexes are located close to the terminus of the respective oxidative addition trajectory...
September 18, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28922604/a-comparative-study-on-the-performance-of-inert-and-functionalized-spheres-coated-with-solid-dispersions-made-of-two-structurally-related-antifungal-drugs
#2
Naila A Mugheirbi, Peter O'Connell, Dolores R Serrano, Anne Marie Healy, Lynne S Taylor, Lidia Tajber
Fluid bed coating offers potential advantages as a formulation platform for amorphous solid dispersions (ASDs) of poorly soluble drugs, being a one-step manufacturing process which could reduce the risk of phase separation associated with multiple step manufacturing approaches. However, the impact of the physicochemical nature of carrier spheres on the properties and drug release from the ASDs has not been studied in detail. In this work, tartaric acid (TAP) and microcrystalline cellulose (CEL) spheres were chosen as examples of functional and inert beads, respectively...
September 18, 2017: Molecular Pharmaceutics
https://www.readbyqxmd.com/read/28922577/functional-n-formyl-peptide-receptor-2-fpr2-antagonists-based-on-ureidopropanamide-scaffold-have-potential-to-protect-against-inflammation-associated-oxidative-stress
#3
Madia Letizia Stama, Enza Lacivita, Liliya N Kirpotina, Mauro Niso, Roberto Perrone, Igor A Schepetkin, Mark T Quinn, Marcello Leopoldo
Formyl peptide receptor-2 (FPR2) is a G protein-coupled receptor belonging to the N-formyl peptide receptor (FPR) family that plays critical roles in peripheral and brain inflammatory responses. FPR2 has been proposed as a target for the development of drugs that could facilitate the resolution of chronic inflammatory reactions by enhancing endogenous anti-inflammation systems. Starting from the structure of the FPR2 agonists (R)- and (S)-4 and 2, we designed a new series of ureidopropanamide derivatives with the goal of converting functional activity from agonism to antagonism and to develop new FPR2 antagonists...
September 18, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28922556/structure-and-mechanism-of-the-monoterpene-cyclolavandulyl-diphosphate-synthase-that-catalyses-consecutive-condensation-and-cyclisation
#4
Tomohisa Kuzuyama, Takeo Tomita, Masaya Kobayashi, Yuma Karita, Yoko Yasuno, Tetsuro Shinada, Makoto Nishiyama
Here, we report the three-dimensional structure of cyclolavandulyl diphosphate (CLPP) synthase (CLDS), which consecutively catalyses the condensation of two molecules of dimethylallyl diphosphate (DMAPP) followed by cyclisation to form a cyclic monoterpene, CLPP. The structures of apo-CLDS and CLDS in complex with Tris, pyrophosphate, and Mg2+ ion were refined at 2.00 Å resolution and 1.73 Å resolution, respectively. CLDS adopts a typical fold for cis-prenyl synthases and forms a homo-dimeric structure. An in vitro reaction using a regiospecifically 2H-substituted DMAPP substrate revealed the intramolecular proton transfer mechanism of the CLDS reaction...
September 18, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28922481/photo-induced-assembly-of-a-luminescent-tetraruthenium-square
#5
Baptiste Laramée-Milette, Francesco Nastasi, Fausto Puntoriero, Sebastiano Campagna, Garry S Hanan
Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl Ru(II) precursor into a discrete molecular square...
September 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28922450/structural-insight-into-the-xtacc3-xmap215-interaction-from-cd-and-nmr-studies-on-model-peptides
#6
Angélica Partida-Hanon, Miguel A Treviño, Miguel Mompeán, Ma Ángeles Jiménez, Marta Bruix
TACC3 is a centrosomal adaptor protein that plays important roles during mitotic spindle assembly. It interacts with chTOG/XMAP215, which catalyzes the addition of tubulin dimers during microtubule growth. A 3D coiled-coil model for this interaction is available but the structural details are not well described. To characterize this interaction at atomic resolution, we have designed a simplified version of the system based on small peptides. Four different peptides have been studied by circular dichroism and nuclear magnetic resonance both singly and in all possible combinations; namely, five peptide pairs and two trios...
September 18, 2017: Biopolymers
https://www.readbyqxmd.com/read/28922082/combinatorial-peptide-based-epitope-mapping-from-ebola-virus-dna-vaccines-and-infections-reveals-residue-level-determinants-of-antibody-binding
#7
Daniel R Ripoll, Daniel A J Mitchell, Lesley C Dupuy, Anders Wallqvist, Connie Schmaljohn, Sidhartha Chaudhury
Ebola virus (EBOV) infection is highly lethal and results in severe febrile bleeding disorders that affect humans and non-human primates. One of the therapeutic approaches for treating EBOV infection focus largely on cocktails of monoclonal antibodies (mAbs) that bind to specific regions of the EBOV glycoprotein (GP) and neutralize the virus. Recent structural studies using cryo-electron microscopy have identified key epitopes for several EBOV mAbs. While such information has yielded deep insights into antibody binding, limitations on resolution of these structures often preclude a residue-level analysis of EBOV epitopes...
September 18, 2017: Human Vaccines & Immunotherapeutics
https://www.readbyqxmd.com/read/28922052/applications-of-emerging-transmission-electron-microscopy-technology-in-pcd-research-and-diagnosis
#8
Amelia Shoemark
Primary Ciliary Dyskinesia (PCD) is a heterogeneous genetic condition characterized by dysfunction of motile cilia. Patients suffer from chronic infection and inflammation of the upper and lower respiratory tract. Diagnosis of PCD is confirmed by identification of a hallmark defect of ciliary ultrastructure or by identification of biallelic pathogenic mutations in a known PCD gene. Since the first description of PCD in 1976, assessment of ciliary ultrastructure by transmission electron microscopy (TEM) has been central to diagnosis and research...
September 18, 2017: Ultrastructural Pathology
https://www.readbyqxmd.com/read/28922031/optic-nerve-head-characteristics-in-chronic-angle-closure-glaucoma-detected-by-swept-source-oct
#9
Dejiao Li, Taibo Li, Eleftherios I Paschalis, Haobing Wang, Elise V Taniguchi, Zi-Ning Choo, Marissa K Shoji, Scott H Greenstein, Stacey C Brauner, Angela V Turalba, Louis R Pasquale, Lucy Q Shen
PURPOSE: To compare structural features in prelaminar and laminar tissues of the optic nerve head (ONH) in chronic angle closure glaucoma (CACG), primary open angle glaucoma (POAG), and control subjects. MATERIALS AND METHODS: ONH imaging was performed using swept-source optical coherence tomography (SS-OCT) for measurements of minimum rim width at Bruch's membrane opening (BMO-MRW), horizontal, and vertical lamina cribrosa depth (LCD). Prelaminar defects, categorized as hole and wedge, and lamina cribrosa (LC) defects were identified...
September 18, 2017: Current Eye Research
https://www.readbyqxmd.com/read/28921966/tool-for-rapid-analysis-of-glycopeptide-by-permethylation-trap-via-one-pot-site-mapping-and-glycan-analysis
#10
Asif Shajahan, Nitin Tatyaso Supekar, Christian Heiss, Mayumi Ishihara, Parastoo Azadi
To overcome the challenges in the analysis of protein glycosylation, we have developed a comprehensive and universal tool through permethylation of glycopeptides and their tandem mass spectrometric analysis. This method has the potential to simplify glycoprotein analysis by integrating glycan sequencing and glycopeptide analysis in a single experiment. Moreover, glycans with unique glycosidic linkages, particularly from prokaryotes, which are resistant to enzymatic or chemical release, could also be detected and analyzed by this methodology...
September 18, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28921913/high-resolution-imaging-of-muscle-attachment-structures-in-c-elegans
#11
Hiroshi Qadota, Yohei Matsunaga, Ken C Q Nguyen, Alexa Mattheyses, David H Hall, Guy M Benian
We used structured illumination microscopy (SIM) to obtain super-resolution images of muscle attachment structures in C. elegans striated muscle. SIM imaging of M-line components revealed two patterns: PAT-3 (β-integrin) and proteins that interact in a complex with the cytoplasmic tail of β-integrin and localize to the basal muscle cell membrane (UNC-112 (kindlin), PAT-4 (ILK), UNC-97 (PINCH), PAT-6 (α-parvin) and UNC-95), are found in discrete, angled segments with gaps. In contrast, proteins localized throughout the depth of the M-line (UNC-89 (obscurin) and UNC-98) are imaged as continuous lines...
September 16, 2017: Cytoskeleton
https://www.readbyqxmd.com/read/28921884/structural-characterization-and-functional-analysis-of-cystathionine-%C3%AE-synthase-an-enzyme-involved-in-the-reverse-transsulfuration-pathway-of-bacillus-anthracis
#12
Suneeta Devi, Syed Arif Abdul Rehman, Khaja Faisal Tarique, Samudrala Gourinath
The reverse transsulfuration pathway has been reported to produce cysteine from homocysteine in eukaryotes ranging from protozoans to mammals while bacteria and plants produce cysteine via a de-novo pathway. Interestingly, the bacterium Bacillus anthracis includes enzymes of the reverse transsulfuration pathway viz. cystathionine β-synthase (BaCBS, previously annotated to be an O-acetylserine sulfhydrylase (OASS)) and cystathionine γ-lyase. Here, we report the structure of BaCBS at a resolution of 2.2 Å...
September 16, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28920937/resolving-ultrafast-exciton-migration-in-organic-solids-at-the-nanoscale
#13
Samuel B Penwell, Lucas D S Ginsberg, Rodrigo Noriega, Naomi S Ginsberg
Effectiveness of molecular-based light harvesting relies on transport of excitons to charge-transfer sites. Measuring exciton migration, however, has been challenging because of the mismatch between nanoscale migration lengths and the diffraction limit. Instead of using bulk substrate quenching methods, here we define quenching boundaries all-optically with sub-diffraction resolution, thus characterizing spatiotemporal exciton migration on its native nanometre and picosecond scales. By transforming stimulated emission depletion microscopy into a time-resolved ultrafast approach, we measure a 16-nm migration length in poly(2,5-di(hexyloxy)cyanoterephthalylidene) conjugated polymer films...
September 18, 2017: Nature Materials
https://www.readbyqxmd.com/read/28920693/ph-tunable-and-divalent-metal-ion-tolerant-polymer-lipid-nanodiscs
#14
Thirupathi Ravula, Nathaniel Hardin, Sudheer Ramadugu, Ayyalusamy Ramamoorthy
The development and applications of detergent-free membrane mimetics have been the focus for the high-resolution structural and functional studies on membrane proteins. The introduction of lipid nanodiscs has attracted new attention towards the structural biology of membrane proteins and also enabled biomedical applications. Lipid nanodiscs provide a native lipid bilayer environment similar to the cell membrane surrounded by a belt made up of proteins or peptides. Recent studies have shown that the hydrolyzed form of styrene maleic anhydride copolymer (SMA) has the ability to form lipid nanodiscs and has several advantages over protein or peptide based nanodiscs...
September 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28920603/controlling-cation-segregation-in-perovskite-based-electrodes-for-high-electro-catalytic-activity-and-durability
#15
REVIEW
Yifeng Li, Wenqiang Zhang, Yun Zheng, Jing Chen, Bo Yu, Yan Chen, Meilin Liu
Solid oxide cell (SOC) based energy conversion systems have the potential to become the cleanest and most efficient systems for reversible conversion between electricity and chemical fuels due to their high efficiency, low emission, and excellent fuel flexibility. Broad implementation of this technology is however hindered by the lack of high-performance electrode materials. While many perovskite-based materials have shown remarkable promise as electrodes for SOCs, cation enrichment or segregation near the surface or interfaces is often observed, which greatly impacts not only electrode kinetics but also their durability and operational lifespan...
September 18, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28920165/distinctive-patterns-in-the-taxonomical-resolution-of-bacterioplankton-in-the-sediment-and-pore-waters-of-contrasted-freshwater-lakes
#16
J Keshri, A S Pradeep Ram, T Sime-Ngando
Bacteria assemblages in lake sediments play a key role in various biogeochemical processes, yet their association with interstitial pore waters has been scarcely investigated. In this study, we utilized Illumina next-generation amplicon sequencing of the 16S rRNA gene to characterize the seasonal bacterial communities in the sediments and pore waters of three contrasted temperate freshwater lakes, namely Pavin, Aydat, and Grangent (French Massif Central). Despite occupying seemingly similar habitats, bacterial communities differed substantially between sediments and pore waters at all seasons with low sharing of operational taxonomic units (OTUs, 6...
September 17, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28919914/agreement-of-clinical-examination-and-ultrasound-methods-for-detection-of-joints-involvements-in-rheumatoid-arthritis
#17
Hadi Karimzadeh, Ramin Rafiei, Zahra Sayedbonakdar, Mehdi Karami
BACKGROUND: Rheumatoid arthritis is a chronic autoimmune disease characterized by synovial tissue inflammation and destruction of articular components which if not controlled properly, can cause disability in patients. For this reason, evaluation of disease activity and its control is very important. In recent years using sonography is promising for the evaluation of disease activity. This study aimed to compare "clinical examination" and "ultrasonography" methods in the detection of disease activity in patients with rheumatoid arthritis...
2017: Journal of Research in Medical Sciences: the Official Journal of Isfahan University of Medical Sciences
https://www.readbyqxmd.com/read/28919350/crystal-structure-of-inositol-1-3-4-5-6-pentakisphosphate-2-kinase-from-cryptococcus-neoformans
#18
Juntaek Oh, Dong-Gi Lee, Yong-Sun Bahn, Sangkee Rhee
The fungal pathogen Cryptococcus neoformans is a causative agent of meningoencephalitis in humans. For its pathogenicity, the inositol polyphosphate biosynthetic pathway plays critical roles. Recently, Ipk1 from C. neoformans (CnIpk1) was identified as an inositol 1,3,4,5,6-pentakisphosphate 2-kinase that catalyzes the phosphorylation of IP5 to form IP6, a substrate for subsequent reaction to produce inositol pyrophosphates, such as PP-IP5/IP7. Furthermore, it was shown that deletion of IPK1 significantly reduces the virulence of C...
September 15, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28919079/structure-of-an-intron-lariat-spliceosome-from-saccharomyces-cerevisiae
#19
Ruixue Wan, Chuangye Yan, Rui Bai, Jianlin Lei, Yigong Shi
The disassembly of the intron lariat spliceosome (ILS) marks the end of a splicing cycle. Here we report a cryoelectron microscopy structure of the ILS complex from Saccharomyces cerevisiae at an average resolution of 3.5 Å. The intron lariat remains bound in the spliceosome whereas the ligated exon is already dissociated. The step II splicing factors Prp17 and Prp18, along with Cwc21 and Cwc22 that stabilize the 5' exon binding to loop I of U5 small nuclear RNA (snRNA), have been released from the active site assembly...
September 8, 2017: Cell
https://www.readbyqxmd.com/read/28918859/a-preliminary-study-of-bipolar-disorder-type-i-by-mass-spectrometry-based-serum-lipidomics
#20
Henrique C Ribeiro, Aline Klassen, Mariana Pedrini, Michelle S Carvalho, Lucas B Rizzo, Mariane N Noto, Maiara Zeni-Graiff, Sumit Sethi, Francisco A H Fonseca, Ljubica Tasic, Mirian A F Hayashi, Quirino Cordeiro, Elisa Brietzke, Alessandra Sussulini
The present study aimed at investigating possible alterations in the serum lipid profile of euthymic patients with bipolar disorder type I (BD) compared to healthy controls (HC). Thirty-five individuals from both genders were recruited, with 14 diagnosed and treated as BD patients (BD group) and 21 healthy subjects (HC group). Clinical assessment was based on the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), Young Mania Rating Scale (YMRS), and 17-items of Hamilton Depression Rating Scale (HDRS-17) data, which were used to confirm diagnosis, to verify psychiatric comorbidities, and to estimate the severity of manic and depressive symptoms...
August 21, 2017: Psychiatry Research
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