scholarly journals Crystal structure of Z-DNA in complex with the polyamine putrescine and potassium cations at ultra-high resolution

Author(s):  
Pawel Drozdzal ◽  
Miroslaw Gilski ◽  
Mariusz Jaskolski

The X-ray crystal structure of the d(CGCGCG)2/putrescine(2+)/K+ complex has been determined at 0.60 Å resolution. Stereochemical restraints were used only for the putrescinium dication, and 23 bonds and 18 angles of the Z-DNA nucleotides with dual conformation. The N atoms of the putrescine(2+) dication form three direct hydrogen bonds with the N7_G atoms of three different Z-DNA molecules, plus three water-mediated hydrogen bonds with cytosine, guanine and phosphate acceptors. A unique potassium cation was also unambiguously identified in the structure, albeit at a ∼0.5 occupation site shared with a water molecule, providing the first example of such a complex with Z-DNA. The K+ cation has coordination number of eight and an irregular coordination sphere, formed by four water molecules and four O atoms from two phosphate groups of the Z-DNA, including ligands present at fractional occupancy. The structural disorder of the Z-DNA duplex is manifested by the presence of alternate conformations along the DNA backbone. Comparison of the position and interactions of putrescine(2+) in the present structure with other ultra-high-resolution structures of Z-DNA in complexes with Mn2+ and Zn2+ ions shows that the dicationic putrescinium moiety can effectively substitute these metal ions for stabilization of Z-type DNA duplexes. Furthermore, this comparison also suggests that the spermine(4+) tetracation has a higher affinity for Z-DNA than K+.

2016 ◽  
Vol 72 (11) ◽  
pp. 1203-1211 ◽  
Author(s):  
Pawel Drozdzal ◽  
Miroslaw Gilski ◽  
Mariusz Jaskolski

The self-complementary d(CGCGCG) hexanucleotide was synthesized with both D-2′-deoxyribose (the natural enantiomer) and L-2′-deoxyribose, and the two enantiomers were mixed in racemic (1:1) proportions and crystallized, producing a new crystal form withC2/csymmetry that diffracted X-rays to 0.78 Å resolution. The structure was solved by direct, dual-space and molecular-replacement methods and was refined to anRfactor of 13.86%. The asymmetric unit of the crystal contains one Z-DNA duplex and three Mg2+sites. The crystal structure is comprised of both left-handed (D-form) and right-handed (L-form) Z-DNA duplexes and shows an unexpectedly high degree of structural disorder, which is manifested by the presence of alternate conformations along the DNA backbone chains as well as at four nucleobases (including one base pair) modelled in double conformations. The crystal packing of the presented D/L-DNA–Mg2+structure exhibits novel DNA hydration patterns and an unusual arrangement of the DNA helices in the unit cell. The paper describes the structure in detail, concentrating on the mode of disorder, and compares the crystal packing of the racemic d(CGCGCG)2duplex with those of other homochiral and heterochiral Z-DNA structures.


2014 ◽  
Vol 70 (5) ◽  
pp. o549-o549
Author(s):  
Yohsuke Nikawa ◽  
Kyoko Fujita ◽  
Keiichi Noguchi ◽  
Hiroyuki Ohno

In the crystal structure of the title compound, C5H14NO4P·H2O, the zwitterionic phosphocholine molecules are connected by an O—H...O hydrogen bond between the phosphate groups, forming a zigzag chain along theb-axis direction. The chains are further connected through O—H...O hydrogen bonds involving water molecules, forming a layer parallel to (101). Three and one C—H...O interactions are also observed in the layer and between the layers, respectively. The conformation of the N—C—C—O backbone isgauchewith a torsion angle of −75.8 (2)°


2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.


2015 ◽  
Vol 71 (11) ◽  
pp. 1384-1387
Author(s):  
Marwen Chouri ◽  
Habib Boughzala

The title compound bis(1,4-diazoniabicyclo[2.2.2]octane) di-μ-chlorido-bis[tetrachloridobismuthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was obtained by slow evaporation at room temperature of a hydrochloric aqueous solution (pH = 1) containing bismuth(III) nitrate and 1,4-diazabicyclo[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10]4−bioctahedra (site symmetry -1) separated by layers of organic 1,4-diazoniabicyclo[2.2.2]octane dications [(DABCOH2)2+] and water molecules. O—H...Cl, N—H...O and N—H...Cl hydrogen bonds lead to additional cohesion of the structure.


2017 ◽  
Vol 73 (11) ◽  
pp. 1599-1602 ◽  
Author(s):  
Matimon Sangsawang ◽  
Kittipong Chainok ◽  
Nanthawat Wannarit

The title compound, [CdNa2(C8H4O4)2(C3H7NO)(H2O)2]nor [CdNa2(1,3-bdc)2(DMF)(H2O)2]n, is a new CdII–NaIheterobimetallic coordination polymer. The asymmetric unit consists of one CdIIatom, two NaIatoms, two 1,3-bdc ligands, two coordinated water molecules and one coordinated DMF molecule. The CdIIatom exhibits a seven-coordinate geometry, while the NaIatoms can be considered to be pentacoordinate. The metal ions and their symmetry-related equivalents are connectedviachelating–bridging carboxylate groups of the 1,3-bdc ligands to generate a three-dimensional framework. In the crystal, there are classical O—H...O hydrogen bonds involving the coordinated water molecules and the 1,3-bdc carboxylate groups and π–π stacking between the benzene rings of the 1,3-bdc ligands present within the frameworks.


Author(s):  
Hongyang Zhang ◽  
Ge Feng ◽  
Alexander S. Filatov ◽  
Richard F. Jordan

In the title compound, C21H21O5PS·H2O·CH2Cl2, the phosphonium–sulfonate zwitterion has the acidic H atom located on the P atom rather than the sulfonate group. The S—O bond lengths [1.4453 (15)–1.4521 (14) Å] are essentially equal. In the crystal, the water molecules bridge two zwitterionsviaOwater—H...Osulfonatehydrogen bonds into a centrosymmetric dimer. The dimers are further linked by weak CAryl—H...Osulfonatehydrogen bonds into chains extending along [100]. The PH+group is not involved in intermolecular interactions.


2017 ◽  
Vol 73 (12) ◽  
pp. 1977-1980
Author(s):  
Volodymyr M. Hiiuk ◽  
Diana D. Barakhty ◽  
Sergiu Shova ◽  
Ruslan A. Polunin ◽  
Il'ya A. Gural'skiy

In the title polymeric complex, {[Fe(C12H10N2)2(H2O)4](CH3C6H4SO3)2·2CH3OH}n, the FeIIcation, located on an inversion centre, is coordinated by four water molecules in the equatorial positions and two 1,2-bis(pyridin-4-yl)ethene molecules in the axial positions. This results in a distorted octahedral geometry for the [N2O4] coordination polyhedron. The 1,2-bis(pyridin-4-yl)ethene molecules bridge the FeIIcations, forming polymeric chains running along thea-axis direction. Stabilization of the crystal structure is provided by O—H...O hydrogen bonds; these are formed by coordinated water molecules as donors towards the O atoms of the methanol molecules and tosylate anions as acceptors of protons, leading to the formation of a three-dimensional supramolecular network. Weak C—H...O hydrogen bonds are also observed in the crystal.


Author(s):  
Graham Smith ◽  
Urs D. Wermuth

In the structure of the brucinium salt of 4-aminophenylarsonic acid (p-arsanilic acid), systematically 2,3-dimethoxy-10-oxostrychnidinium 4-aminophenylarsonate tetrahydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water molecules of solvation are accommodated between the layers and are linked to them through a primary cation N—H...O(anion) hydrogen bond, as well as through water O—H...O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.


IUCrData ◽  
2020 ◽  
Vol 5 (10) ◽  
Author(s):  
Erika Samolová ◽  
Jan Fábry

The crystal structure of the title complex, [Pb3(C4H7O2)6(H2O)2] n , was redetermined on basis of modern CCD-based single-crystal X-ray data at 120 K. The current study basically confirms the previous report [Fallon et al. (1997). Polyhedron, 16, 19–23] at 190 K, but with higher accuracy and precision. In particular, positional disorder of one of the 2-methylpropanoate anions over two sets of sites was resolved, showing a refined ratio of the disorder components of 0.535 (9):0.465 (9). The three independent cations in the structure have coordination numbers of [7 + 1], [6 + 1], and [5 + 3], with O atoms belonging either to carboxylate groups or water molecules. This arrangement leads to the formation of sheets parallel to (\overline{1}01), whereby the hydrophobic 2-methylpropanyl groups of the anions are oriented above and below the hydrophilic sheets to form a layered structure. Within a sheet, hydrogen bonds of the type Owater—H...O are formed, whereas the hydrophobic groups between adjacent layers interact through van der Waals forces.


1987 ◽  
Vol 42 (8) ◽  
pp. 972-976 ◽  
Author(s):  
Christian Robl

AbstractSingle crystals of EA[Q(NO2)2O4] · 4H2O (EA = Ca. Sr) were grown in aqueous silicagel. Ca2+ has CN 8. It is surrounded by 4 oxygen atoms of two bis-chelating [C6(NO2)2O4]2- ions and 4 water molecules, which form a distorted, bi-capped trigonal prism. Sr2+ is coordinated similarly, with an additional water molecule joining the coordination sphere to yield CN 8+1. Corrugated chains extending along [010] and consisting of EA2+ and nitranilate ions are the main feature of the crystal structure. Adjacent chains are interlinked by hydrogen bonds.


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