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101.
Dr. Stefano Elli Dr. Eduardo Stancanelli Dr. Zhangjie Wang Dr. Maurice Petitou Prof. Jian Liu Dr. Marco Guerrini 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(51):11814-11818
Heparin binds to and activates antithrombin (AT) through a specific pentasaccharide sequence, in which a trisaccharide subsite, containing glucuronic acid (GlcA), has been considered as the initiator in the recognition of the polysaccharide by the protein. Recently it was suggested that sulfated iduronic acid (IdoA2S) could replace this “canonical” GlcA. Indeed, a heparin octasaccharidic sequence obtained by chemoenzymatic synthesis, in which GlcA is replaced with IdoA2S, has been found to similarly bind to and activate antithrombin. By using saturation-transfer-difference (STD) NMR, NOEs, transferred NOEs (tr-NOEs) NMR and molecular dynamics, we show that, upon binding to AT, this IdoA2S unit develops comparable interactions with AT as GlcA. Interestingly, two IdoA2S units, both present in a 1C4-2S0 equilibrium in the unbound saccharide, shift to full 2S0 and full 1C4 upon binding to antithrombin, providing the best illustration of the critical role of iduronic acid conformational flexibility in biological systems. 相似文献
102.
A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Cu(II) ions assemble in alternating chains with Cu … Cu distances of 2.5685(4) and 3.1760(4) Å. The temperature dependence of the magnetic susceptibility reveals an antiferromagnetic interaction between the paddle-wheel copper centers with an exchange of −300 cm−1. The exchange integral was also determined by quantum chemical ab-initio calculations, using polarised and unpolarised basis sets reproducing well the experimental value. The second harmonic generation efficiency of a concomitantly crystallized material was evaluated and was found to be comparable to urea. 相似文献
103.
Stephen D. Pastor David N. Rahni Nancy Khoury Stephen A. Koch 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1951-1956
The X-ray crystallographic analysis of 6,6-dimethyl-2,4,8,10-tetra-tert-octyl-dibenzo[d,f][1,3,2]dioxagermepin, 1 is reported. In the solid-state conformation of 1, the dihedral angle about the C─C sp2-sp 2 σ bond connecting the two aryl rings is 50.1°. The observed C2 symmetry in the solid-state conformation of 1 is consistent with the previously suggested solution conformation. 相似文献
104.
Yoshio Aso Shoji Nishiguchi Tetsuya Jigami Tetsuo Otsubo Fumio Ogura 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):417-418
Several well-defined 3,4-thienylene-ethynylene oligomers with different chain lengths have been synthesized and characterized. X-Ray crystallographic analyses proved their unique, totally helical conformations. 相似文献
105.
Felix Katzsch Tobias Gruber Edwin Weber 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(9):679-684
The syntheses of three bis(benzo[b]thiophen‐2‐yl)methane derivatives, namely bis(benzo[b]thiophen‐2‐yl)methanone, C17H10OS2, (I), 1,1‐bis(benzo[b]thiophen‐2‐yl)‐3‐(trimethylsilyl)prop‐2‐yn‐1‐ol, C22H20OS2Si, (II), and 1,1‐bis(benzo[b]thiophen‐2‐yl)prop‐2‐yn‐1‐ol, C19H12OS2, (III), are described and their crystal structures discussed comparatively. The conformation of ketone (I) and the respective analogues are rather similar for most of the compounds compared. This is true for the interplanar angles, the Caryl—Cbridge—Caryl angles and the dihedral angles. The best resemblance is found for a bioisotere of (I), viz. 2,2′‐dinaphthyl ketone, (VII). By way of interest, the crystal packings also reveal similarities between (I) and (VII). In (I), the edge‐to‐face interactions seen between two napthyl residues in (VII) are substituted by S…π contacts between the benzo[b]thiophen‐2‐yl units in (I). In the structures of the bis(benzo[b]thiophen‐2‐yl)methanols, i.e. (II) and (III), the interplanar angles are also quite similar compared with analogues and related active pharmaceutical ingredients (APIs) containing the dithiophen‐2‐ylmethane scaffold, though the dihedral angles show a larger variability and produce unsymmetrical molecules. 相似文献
106.
107.
108.
Tadanori Kurosawa An-Dih Yu Tomoya Higashihara Wen-Chang Chen Mitsuru Ueda 《European Polymer Journal》2013
Two polyimides, PI(DAT-6FDA) and PI(DAPT-6FDA), from N-(2,4-diaminophenyl)-N,N-diphenylamine (DAT) or N-(4-(2′,4′-diaminophenoxy)phenyl-N,N-diphenylamine (DAPT) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were prepared to clarify the structural effect on the resulting memory properties. The memory device based on PI(DAT-6FDA) showed an unstable volatile behavior, while the device based on PI(DAPT-6FDA) with a more bulky donor (D) unit exhibited a stable non-volatile FLASH type memory characteristic with a long retention time over 104 s. The theoretical simulation based on the density functional theory (DFT) suggested that the greater distinct charge separation between the ground and charge transfer (CT) states led to a highly stable memory behavior. Also, it was clarified that PI(DAPT-6FDA) had a highly twisted conformation compared to PI(DAT-6FDA) in the ground state, and a more twisted dihedral angle between the D and acceptor (A) units was induced in the CT state, which led to the non-volatile memory characteristic. 相似文献
109.
Harshanie Abeywardena Aaron R. Jex Simon M. Firestone Sandra McPhee Nicole Driessen Anson V. Koehler Shane R. Haydon Georg von Samson‐Himmelstjerna Melita A. Stevens Robin B. Gasser 《Electrophoresis》2013,34(15):2259-2267
In the present study, we undertook a molecular epidemiological survey of Cryptosporidium and Giardia in calves on three dairy and two beef farms within an open drinking water catchment area (Melbourne, Australia). Faecal samples (n = 474) were collected from calves at two time points (5 months apart) and tested using a PCR‐based mutation scanning‐targeted sequencing phylogenetic approach, employing regions within the genes of small subunit (SSU) of ribosomal RNA (designated partial SSU), 60 kDa glycoprotein (pgp60) and triose phosphate isomerase (ptpi) as genetic markers. Using partial SSU, the C. bovis, C. parvum, C. ryanae and a new genotype of Cryptosporidium were characterised from totals of 74 (15.6%), 35 (7.3%), 37 (7.8%) and 9 (1.9%) samples, respectively. Using pgp60, C. parvum genotype IIa subgenotype A18G3R1 was detected in 29 samples. Using ptpi, G. duodenalis assemblages A and E were detected in totals of 10 (2.1%) and 130 (27.4%) samples, respectively. The present study showed that a considerable proportion of dairy and beef calves in this open water catchment region excreted Cryptosporidium (i.e. subgenotype IIaA18G3R1) and Giardia (e.g. assemblage A) that are consistent with those infecting humans, inferring that they are of zoonotic importance. Future work should focus on exploring, in a temporal and spatial way, whether these parasites occur in the environment and water of the catchment reservoir. 相似文献
110.
Sandra C. C. Nunes P. Pinto A. A. C. C. Pais 《Journal of computational chemistry》2013,34(14):1198-1209
Adsorption phenomena are relevant in a wide variety of subjects, from biophysics to technological applications. Different aspects, such as molecular recognition, multilayer deposition, and dynamics of polymer adsorption have been addressed. The methodologies used range from analytical and numerical methods to molecular dynamics or Monte Carlo simulations. In this work, a coarse‐grained model is used to explore the adsorption of charged backbones to oppositely charged regions of a surface. These regions encompass those small enough to prevent complete adsorption, but extend to surfaces sufficiently large to promote adsorption with minimal effect on the three‐dimensional conformation in bulk. Apart from the different surface areas explored, variations on the surface charge density, polyelectrolyte chain length, and chain stiffness were also considered. The degree of compaction of the polyelectrolyte, on adsorption, is different from that found in the bulk. Also, results indicate an nonuniform adsorption pattern on regularly charged surfaces. © 2013 Wiley Periodicals, Inc. 相似文献