共查询到20条相似文献,搜索用时 234 毫秒
1.
Guangzong Tian Jing Hu Chunjun Qin Lingxin Li Xiaopeng Zou Juntao Cai Peter H. Seeberger Jian Yin 《Angewandte Chemie (International ed. in English)》2020,59(32):13362-13370
The development of glycoconjugate vaccines against Helicobacter pylori is challenging. An exact epitope of the H. pylori lipo‐polysaccharide (LPS) O‐antigens that contain Lewis determinant oligosaccharides and unique dd ‐heptoglycans has not yet been identified. Reported here is the first total synthesis of H. pylori serotype O6 tridecasaccharide O‐antigen containing a terminal Ley tetrasaccharide, a unique α‐(1→3)‐, α‐(1→6)‐, and α‐(1→2)‐linked heptoglycan, and a β‐d ‐galactose connector, by an [(2×1)+(3+8)] assembly sequence. Seven oligosaccharides covering different portions of the entire O‐antigen were prepared for immunological investigations with a particular focus on elucidation of the roles of the dd ‐heptoglycan and Ley tetrasaccharide. Glycan microarray analysis of sera from rabbits immunized with isolated serotype O6 LPS revealed a humoral immune response to the α‐(1→3)‐linked heptoglycan, a key motif for designing glycoconjugate vaccines for H. pylori serotype O6. 相似文献
2.
Anna N. Kondakova Evgeny Vinogradov Buko Lindner Nina A. Kocharova Antoni Rozalski Yuriy A. Knirel 《Journal of carbohydrate chemistry》2013,32(6):499-520
Enterobacteria of the genus Providencia are opportunistic pathogens causing diarrhea in travelers and children. Lipopolysaccharide (LPS) is the major surface antigen of Providencia and the major target of the immune response. O‐polysaccharide structures have been elucidated in several Providencia O‐serogroups, but little is known about the LPS core structure. We isolated core oligosaccharides from the R‐type LPS of a number of Providencia O‐serogroups and studied them by high‐resolution mass spectrometry, including capillary skimmer dissociation technique; three selected oligosaccharides were analyzed also by NMR spectroscopy. The conserved inner core and variable outer core regions were distinguished and the full core oligosaccharide structures established in Providencia O8, O35, and O49. Providencia LPSs were found to share some structural features with Proteus LPSs. 相似文献
3.
Shan Gao Ji‐Wei Liu Li‐Hua Huo Zhi‐Zhong Sun Jin‐Sheng Gao Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):m363-m365
In the title neutral coordination polymer, [Cd(C6H3ClNO2)2(H2O)2]n, each CdII ion is coordinated by one N and four O atoms from three 2‐chloronicotinate ligands and by two aqua ligands, defining a distorted monocapped octahedral coordination geometry. Adjacent Cd atoms are linked by the pyridyl N atom and the bidentate carboxylate functional group of a 2‐chloronicotinate ligand, forming a one‐dimensional infinite chain along the b axis. The Cd⋯Cd distance is 8.112 (3) Å. These chains are linked by O—H⋯O and O—H⋯N hydrogen bonds into a three‐dimensional network structure. 相似文献
4.
K. Manoj S. Devaraj R. G. Gonnade M. M. Bhadbhade M. S. Shashidhar 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(11):o628-o630
The centrosymmetric O—H⋯O‐bonded head‐to‐head dimers of the title compound, C21H22O6, are linked together via bifurcated C—H⋯O interactions along the a axis and via favourable C—H⋯π interactions along the b axis in the crystal structure. 相似文献
5.
Dr. Henry G. Hocking Dr. Gerrit J. Gerwig Dr. Sébastien Dutertre Dr. Aude Violette Dr. Philipe Favreau Dr. Reto Stöcklin Prof. Dr. Johannis P. Kamerling Prof. Dr. Rolf Boelens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):870-879
The glycopeptide CcTx, isolated from the venom of the piscivorous cone snail Conus consors, belongs to the κA‐family of conopeptides. These toxins elicit excitotoxic responses in the prey by acting on voltage‐gated sodium channels. The structure of CcTx, a first in the κA‐family, has been determined by high‐resolution NMR spectroscopy together with the analysis of its O‐glycan at Ser7. A new type of glycopeptide O‐glycan core structure, here registered as core type 9, containing two terminal L ‐galactose units {α‐L ‐Galp‐(1→4)‐α‐D ‐GlcpNAc‐(1→6)‐[α‐L ‐Galp‐(1→2)‐β‐D ‐Galp‐(1→3)‐]α‐D ‐GalpNAc‐(1→O)}, is highlighted. A sequence comparison to other putative members of the κA‐family suggests that O‐linked glycosylation might be more common than previously thought. This observation alone underlines the requirement for more careful and in‐depth investigations into this type of post‐translational modification in conotoxins. 相似文献
6.
Bernard Marciniak 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):o419-o422
The asymmetric unit of the title compound, C10H8O2, contains two practically planar symmetry‐independent molecules linked by one O—H...O hydrogen bond. Molecules are further linked into a three‐dimensional network, which is built from R66(36), R66(18), R66(30) and R44(26) rings formed by the combined effect of three O—H...O and one C—H...O hydrogen bond. This network is additionally stabilized by an O—H...π interaction. 相似文献
7.
brahim Uar Okan Zafer Yeilel Ahmet Bulut Hasan budak Halis
lmez Canan Kazak 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(8):m392-m394
In the crystal structure of the title compound, [Cd(C6H15NO3)2](C4O4)·H2O, a supramolecular structure is observed. The asymmetric unit consists of one unit of the cationic Cd complex, one water molecule and two half‐squarate anions, each sitting on a crystallographic inversion center. The different coordinations of the two triethanolamine (TEA) ligands results in an unusual example of coordination number seven for the CdII ion. Both TEA ligands coordinate to the CdII ion, forming a distorted monocapped trigonal prismatic geometry with approximate C2v symmetry. One of the TEA ligands acts as an N,O,O′‐tridentate ligand, whereas the other behaves as an N,O,O′,O′′‐tetradentate donor. The anions and cations are linked to one another by hydrogen bonds between hydroxy H atoms of the TEA ligands and squarate O atoms. The crystal structure is stabilized by O—H⋯O hydrogen bonds between the unligated water molecule and a squarate O atom, together with a weak π–ring interaction between the ethylene group of a TEA ligand and a squarate anion. 相似文献
8.
Christopher Glidewell John N. Low Manuel Melguizo Antonio Quesada 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):o14-o18
In 2‐amino‐4,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, the molecules are linked by one N—H⋯N and one N—H⋯O hydrogen bond to form sheets built from alternating R(8) and R(32) rings. In isomeric 4‐amino‐2,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, which crystallizes with Z′ = 2 in P, the two independent molecules are linked into a dimer by two independent N—H⋯N hydrogen bonds. These dimers are linked into sheets by a combination of two‐centre C—H⋯O and three‐centre C—H⋯(O)2 hydrogen bonds, and the sheets are further linked by two independent aromatic π–π‐stacking interactions to form a three‐dimensional structure. 相似文献
9.
Muhammad Altaf Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o441-o445
The title compounds, C10H9N5O·H2O (L1·H2O) and C16H12N6O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P21/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H2O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H2O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present. 相似文献
10.
Immacolata Speciale Flaviana Di Lorenzo Valentina Gargiulo Gitte Erbs Mari‐Anne Newman Antonio Molinaro Cristina De Castro 《Angewandte Chemie (International ed. in English)》2020,59(16):6368-6374
The lipopolysaccharide (LPS) O‐antigen structure of the plant pathogen Rhizobium radiobacter strain TT9 and its possible role in a plant‐microbe interaction was investigated. The analyses disclosed the presence of two O‐antigens, named Poly1 and Poly2. The repetitive unit of Poly2 constitutes a 4‐α‐l ‐rhamnose linked to a 3‐α‐d ‐fucose residue. Surprisingly, Poly1 turned out to be a novel type of biopolymer in which the repeating unit is formed by a monosaccharide and an amino‐acid derivative, so that the polymer has alternating glycosidic and amidic bonds joining the two units: 4‐amino‐4‐deoxy‐3‐O‐methyl‐d ‐fucose and (2′R,3′R,4′S)‐N‐methyl‐3′,4′‐dihydroxy‐3′‐methyl‐5′‐oxoproline). Differently from the O‐antigens of LPSs from other pathogenic Gram‐negative bacteria, these two O‐antigens do not activate the oxidative burst, an early innate immune response in the model plant Arabidopsis thaliana, explaining at least in part the ability of this R. radiobacter strain to avoid host defenses during a plant infection process. 相似文献
11.
Heng Zhang Liangliang Chang Na Wang Xiaopeng Xuan 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1173-1176
The title compound, C6H9N2O2+·Cl−·C6H8N2O2·H2O, contains one 2‐(3‐methyl‐1H‐imidazol‐3‐ium‐1‐yl)acetate inner salt molecule, one 1‐carboxymethyl‐3‐methyl‐1H‐imidazol‐3‐ium cation, one chloride ion and one water molecule. In the extended structure, chloride anions and water molecules are linked via O—H...Cl hydrogen bonds, forming an infinite one‐dimensional chain. The chloride anions are also linked by two weak C—H...Cl interactions to neighbouring methylene groups and imidazole rings. Two imidazolium moieties form a homoconjugated cation through a strong and asymmetric O—H...O hydrogen bond of 2.472 (2) Å. The IR spectrum shows a continuous D‐type absorption in the region below 1300 cm−1 and is different to that of 1‐carboxymethyl‐3‐methylimidazolium chloride [Xuan, Wang & Xue (2012). Spectrochim. Acta Part A, 96 , 436–443]. 相似文献
12.
Shobhana Krishnaswamy Rajesh G. Gonnade Mohan M. Bhadbhade Mysore S. Shashidhar 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):o54-o57
The title compound, C17H16O8, yields conformational dimorphs [forms (I) and (II)] at room temperature, separately or concomitantly, depending on the solvent of crystallization. The yield of crystals of form (I) is always much more than that of crystals of form (II). The molecule has one donor –OH group that can make intermolecular O—H...O hydrogen bonds with one of the two acceptor C=O groups, as well as with the hydroxyl O atom; interestingly, each of the options is utilized separately in the dimorphs. The crystal structure of form (I) contains one molecule in the asymmetric unit and is organized as a planar sheet of centrosymmetric dimers via O—H...O hydrogen bonds involving the OH group and the carbonyl O atom of the acryloyl group. In the crystal structure of form (II), which contains two independent molecules in the asymmetric unit, two different O—H...O hydrogen bonds, viz. hydroxyl–hydroxyl and hydroxyl–carbonyl (benzoyl), connect the molecules in a layered arrangement. Another notable feature is the transformation of form (II) to form (I) via melt crystallization upon heating to 411 K. The higher yield of form (I) during crystallization and the thermal transition of form (II) to form (I) suggest that the association in form (I) is more highly favoured than that in form (II), which is valuable in understanding the priorities of molecular aggregation during nucleation of various polymorphs. 相似文献
13.
Eleonora Freire Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):m164-m166
The present form of barium acetate, formulated as [Ba(C2H3O2)2(H2O)3]n, is the largest reported hydrate of the salt and this leads to a distinct structural behaviour setting it apart from the rest of the family. The compound is a linear polymer with a nine‐coordinate Ba(Oaqua)3(Oacetate)6 monomer unit. The non‐H part of the structure is ordered according to C2/m symmetry, while the disordered water H atoms only abide by this symmetry in a statistical sense. Each molecule is halved by a mirror plane bisecting the Ba centre, one water molecule and one acetate ligand, while containing the other acetate ligand. The chains are interconnected by a disordered water–water/acetate O—H...O hydrogen‐bonding network involving all water H atoms. The structure and stability of this phase are compared with the other known acetates of barium which differ in the degree of hydration. 相似文献
14.
Ana María Atria Maria Teresa Garland Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(7):m185-m188
The title ionic compound, (C7H8N3)2[Ho2(C4H5O2)8], is constructed from two almost identical independent centrosymmetric anionic dimers balanced by two independent 2‐amino‐1H‐benzimidazol‐3‐ium (Habim+) cations. The asymmetric part of each dimer is made up of one HoIII cation and four crotonate (crot or but‐2‐enoate) anions, two of them acting in a simple η2‐chelating mode and the remaining two acting in two different μ2:η2 fashions, viz. purely bridging and bridging–chelating. Symmetry‐related HoIII cations are linked by two Ho—O—Ho and two Ho—O—C—O—Ho bridges which lead to rather short intracationic Ho...Ho distances [3.8418 (3) and 3.8246 (3) Å]. In addition to the obvious Coulombic interactions linking the cations and anions, the isolated [Ho2(crot)8]2− and Habim+ ions are linked by a number of N—H...O hydrogen bonds, in which all N—H groups of the cation are involved as donors and all (simple chelating) crot O atoms are involved as acceptors. These interactions result in compact two‐dimensional structures parallel to (110), which are linked to each other by weaker π–π contacts between Habim+ benzene groups. 相似文献
15.
Qiu‐Ying Huang Yu‐Hong Zhang Xiang‐Ru Meng 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(4):306-310
In the title coordination polymer, catena‐poly[[bis[{1‐[(1H‐benzimidazol‐2‐yl‐κN3)methyl]‐1H‐tetrazole}zinc(II)]‐bis(μ4‐pentane‐1,5‐dioato‐1:2:1′:2′κ4O1:O1′:O5:O5′)] methanol disolvate], {[Zn(C5H6O4)(C9H8N6)]·CH3OH}n, each ZnII ion is five‐coordinated by four O atoms from four glutarate ligands and by one N atom from a 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole (bimt) ligand, leading to a slightly distorted square‐pyramidal coordination environment. Two ZnII ions are linked by four bridging glutarate carboxylate groups to generate a dinuclear [Zn2(CO2)4] paddle‐wheel unit. The dinuclear units are further connected into a one‐dimensional chain via the glutarate ligands. The bimt ligands coordinate to the ZnII ions in a monodentate mode and are pendant on both sides of the main chain. In the crystal, the chains are linked by O—H...O and N—H...O hydrogen bonds into a two‐dimensional layered structure. Adjacent layers are further packed into a three‐dimensional network through van der Waals forces. A thermogravimetric analysis was carried out and the photoluminescent behaviour of the polymer was investigated. 相似文献
16.
K. Manoj R. G. Gonnade M. M. Bhadbhade M. S. Shashidhar 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):o335-o338
In the absence of conventional hydrogen bonding, the molecules of 4,6‐di‐O‐acetyl‐2‐O‐tosyl‐myo‐inositol 1,3,5‐orthoformate, C18H20O10S, (I), and 4,6‐di‐O‐acetyl‐2‐O‐tosyl‐myo‐inositol 1,3,5‐orthobenzoate, C24H24O10S, (II), are associated via C—H...O interactions. Molecules of (II) are additionally linked via dipolar S=O...C=O contacts. It is interesting to note that the sulfonyl O atom involved in the dipolar S=O...C=O contacts does not take part in any other interaction, indicating the competitive nature of this contact relative to the weak hydrogen‐bonding interactions. 相似文献
17.
Christian Neis Bernd Morgenstern Kaspar Hegetschweiler 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(1):28-34
A first preliminary report on the crystal structure of a hydrated salt formulated as [Ge(taci)2]Cl4·13H2O (taci is 1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol) appeared more than 20 years ago [Ghisletta (1994). PhD thesis, ETH Zürich. Switzerland]. At that time it was not possible to discriminate unambiguously between the positions of some of the chloride ions and water O atoms, and disorder was thus postulated. In a new determination, a conclusive scheme of hydrogen bonding proves to be a particularly appealing aspect of the structure. Single crystals of the title compound, C12H30GeN6O64+·4Cl−·6H2O or [Ge(taci)2]2Cl8·12H2O, were grown from an aqueous solution by slow evaporation of the solvent. The two [Ge(taci)2]4+ cations exhibit a double‐adamantane‐type structure with exclusive O‐atom coordination and approximate D3d symmetry. The taci ligands adopt a zwitterionic form with deprotonated hydroxy groups and protonated amino groups. Both cations are hydrogen bonded to six water molecules. The structure of the hydration shell of the two cations is, however, slightly different. The {[Ge(taci)2]·6H2O}4+ aggregates are interlinked in all three dimensions by further hydrogen bonds of the types N—H...Cl...H—N, N—H...O(H)2...H—N, (Ge)O...H—O(H)...H—N, N—H...O(H)—H...Cl...H—N, (Ge)O...H—O—H...Cl...H—N, N—H...O(H)—H...Cl...H—(H)O...H—N, (Ge)O...H—O—H...Cl...H—(H)O...H—N and Ge(O)...H—O—H...Cl...H—O—H...O(Ge). 相似文献
18.
Helen Stoeckli‐Evans Olha Sereda Antonia Neels Sebastien Oguey Catherine Ionescu Yvan Jacquier 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(11):1057-1063
The one‐dimensional coordination polymer catena‐poly[diaqua(sulfato‐κO)copper(II)]‐μ2‐glycine‐κ2O:O′], [Cu(SO4)(C2H5NO2)(H2O)2]n, (I), was synthesized by slow evaporation under vacuum of a saturated aqueous equimolar mixture of copper(II) sulfate and glycine. On heating the same blue crystal of this complex to 435 K in an oven, its aspect changed to a very pale blue and crystal structure analysis indicated that it had transformed into the two‐dimensional coordination polymer poly[(μ2‐glycine‐κ2O:O′)(μ4‐sulfato‐κ4O:O′:O′′:O′′)copper(II)], [Cu(SO4)(C2H5NO2)]n, (II). In (I), the CuII cation has a pentacoordinate square‐pyramidal coordination environment. It is coordinated by two water molecules and two O atoms of bridging glycine carboxylate groups in the basal plane, and by a sulfate O atom in the apical position. In complex (II), the CuII cation has an octahedral coordination environment. It is coordinated by four sulfate O atoms, one of which bridges two CuII cations, and two O atoms of bridging glycine carboxylate groups. In the crystal structure of (I), the one‐dimensional polymers, extending along [001], are linked via N—H...O, O—H...O and bifurcated N—H...O,O hydrogen bonds, forming a three‐dimensional framework. In the crystal structure of (II), the two‐dimensional networks are linked via bifurcated N—H...O,O hydrogen bonds involving the sulfate O atoms, forming a three‐dimensional framework. In the crystal structures of both compounds, there are C—H...O hydrogen bonds present, which reinforce the three‐dimensional frameworks. 相似文献
19.
Alain Bekaert Pascale Lemoine Jean Daniel Brion Bernard Viossat 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):m76-m77
The title compound, tris[(R)‐2‐hydroxypropanamide‐κ2O,O′]zinc(II) tetrabromozincate, [Zn(C3H7NO2)3][ZnBr4], contains one monomeric six‐coordinate zinc complex cation and one tetrahedral [ZnBr4]2− anion. Both ZnII atoms lie on threefold axes. Coordination in the cation occurs via the amide and hydroxy O atoms [Zn—O = 2.074 (5) and 2.073 (6) Å] and has a distorted octahedral geometry, with cis‐O—Zn—O angles in the range 76.2 (2)–109.2 (2)°. In the crystal structure, the cations and anions are linked by N—H⋯Br and O—H⋯O hydrogen bonds, generating a three‐dimensional network. 相似文献
20.
Jos M. de la Torre Manuel Nogueras Justo Cobo John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o638-o640
The title compound [systematic name: 6‐amino‐5‐formyl‐1,3‐dimethylpyrimidine‐2,4(1H,3H)‐dione monohydrate], C7H9N3O3·H2O, has been reexamined at 120 K. The improved precision of the intramolecular dimensions provides evidence for a polarized molecular–electronic structure, and the molecular components are linked by one N—H...O and two O—H...O hydrogen bonds into two interwoven three‐dimensional frameworks, which are weakly linked by the longer component of a three‐centre N—H...(O)2 hydrogen bond. 相似文献