scholarly journals Structure of α-carbonic anhydrase from the human pathogenHelicobacter pylori

2015 ◽  
Vol 71 (8) ◽  
pp. 1005-1011 ◽  
Author(s):  
Maria Elena Compostella ◽  
Paola Berto ◽  
Francesca Vallese ◽  
Giuseppe Zanotti
Keyword(s):  
Crystal Structure ◽  
Carbonic Anhydrase ◽  
Bacterial Colonization ◽  
Human Stomach ◽  
Negative Ion ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Antibiotic Drugs ◽  
H Pylori ◽  
Definition Of

The crystal structure of α-carbonic anhydrase, an enzyme present in the periplasm ofHelicobacter pylori, a bacterium that affects humans and that is responsible for several gastric pathologies, is described. Two enzyme monomers are present in the asymmetric unit of the monoclinic space groupP21, forming a dimer in the crystal. Despite the similarity of the enzyme structure to those of orthologues from other species, theH. pyloriprotein has adopted peculiar features in order to allow the bacterium to survive in the difficult environment of the human stomach. In particular, the crystal structure shows how the bacterium has corrected for the mutation of an essential amino acid important for catalysis using a negative ion from the medium and how it localizes close to the inner membrane in the periplasm. Since carbonic anhydrase is essential for the bacterial colonization of the host, it is a potential target for antibiotic drugs. The definition of the shape of the active-site entrance and cavity constitutes a basis for the design of specific inhibitors.

Studies on Crown Ether Complexes. XXXI. Synthesis, Properties and Structure of the Complexes of Lighter Lanthanide Nitrates With (Z)-2,3-Diphenyl-1,4,7,10,13-pentaoxacyclopentadec-2-ene (Stilbeno-15-crown-5)

1993 ◽  
Vol 46 (11) ◽  
pp. 1817 ◽  
Author(s):  
TB Lu ◽  
N Tang ◽  
MY Tan ◽  
Y Liu ◽  
KB Yu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Conductivity Measurements ◽  
X Ray ◽  
Elemental Analyses ◽  
Crown Ether Complexes ◽  
Synthesis Properties ◽  
Lanthanide Nitrates ◽  
Ray Methods

Complexes of the lighter lanthanide nitrates with stilbeno-15-crown-5 (L) have been prepared in ethyl acetate. These new complexes with the general formula Ln (NO3)3.L.H2O ( Ln = La, Ce , Pr, Nd ) have been characterized by means of elemental analyses, i.r . spectra, 1H n.m.r. spectra and conductivity measurements. The crystal structure of La(NO3)3.L has been determined by X-ray methods, and refined to a residual R 0.0513 for 4937 independent reflections with I ≥ 1.5σ(I). It crystallizes in the monoclinic space group P21/a with a 16.090(5), b 15.654(8), c 22.687(2) Ǻ, β 93.96(4)°, V 5700(4)Ǻ3, and Z 8. There are two independent La(NO3)3.L monomers in one asymmetric unit; in each the coordination number is 11.

Barrydawsonite-(Y), Na1.5CaY0.5Si3O9H: a new pyroxenoid of the pectolite–serandite group

2015 ◽  
Vol 79 (3) ◽  
pp. 671-686 ◽  
Author(s):  
R. H. Mitchell ◽  
M. D. Welch ◽  
A. R. Kampf ◽  
A. K. Chakhmouradian ◽  
J. Spratt
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Red Wine ◽  
Structural Formula ◽  
Potassium Feldspar ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
X Ray ◽  
Final Agreement ◽  
Simplified Formula

AbstractThe new pyroxenoid barrydawsonite-(Y) occurs at the Merlot Claim, North Red Wine Pluton, Labrador, Canada (62°32'38.54'' W; 54°08'1.37'' N). The host rock is a metamorphosed eudialyte syenite consisting of eudialyte, potassic arfvedsonite, jadeitic aegirine, nepheline, albite and potassium feldspar with accessory Y-bearing pectolite, britholite and steenstrupine. Barrydawsonite-(Y) crystals commonly have discrete thin rims of Y-bearing pectolite. The average empirical formula (based on nine anions p.f.u.) is Na1.54Ca0.74Mn0.15Fe0.07Y0.38Nd0.01Sm0.01Gd0.02Tb0.01Dy0.04Ho0.01Er0.02Yb0.01Si3.00O9H. The simplified formula is Na1.5Y0.5CaSi3O9H. Barrydawsonite-(Y) is related to pectolite by the substitution ½[NaM3+Ca–2] (M3+ = Y,REE), and is exceptional in being the only member of the pectolite group that has the structure of the monoclinic M2abc polytype. The crystal structure has been determined in monoclinic space group P21/a: a = 15.5026(2), b = 7.0233(1), c = 6.9769(1) Å, β = 95.149(1)°, V = 756.58(2) Å3(Z = 4). Final agreement indices are R1 = 0.038, wR2 = 0.068, Goof = 1.136. The asymmetric unit of barrydawsonite-(Y) has three metal sites: M(1) = Ca, M(2) = Na0.5(Y,REE)0.5, M(3) = Na. M(1) and M(2) are octahedrally-coordinated sites, whereas M(3) is [8]-coordinated as in pectolite and serandite. The structural formula for the empirical composition is M(3)Na1.00M(2)(Na0.50Y0.38REE0.13)Σ=1.01M(1)(Na0.04Ca0.74Mn0.152+Fe0.072+)Σ=1.00Si3O9H. There is excellent agreement between the refined site-scattering values and those calculated based upon the structural formula.Barrydawsonite-(Y) is biaxial (+) with α = 1.612(1), β = 1.617(1), γ = 1.630(1) (white light) and 2V = 63(1)°. The five strongest peaks in the X-ray powder diffraction pattern are [dobs (Å), Iobs%, (hkl)]: [2.905, 100, (023)], [3.094, 30, (210,211,121,202)], [1.7613, 29, (127,323,040)], [3.272, 27, (202,104)], [1.7016, 27, (140,227,325)].

scholarly journals Synthesis and crystal structure of 1,3-di-tert-butyl-2-chloro-4,4-diphenyl-1,3,2λ3,4-diazaphosphasiletidine

2019 ◽  
Vol 75 (3) ◽  
pp. 405-409 ◽  
Author(s):  
Dennis Mo ◽  
Walter Frank
Keyword(s):  
Crystal Structure ◽  
Membered Ring ◽  
Mean Deviation ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Reduced Pressure ◽  
Synthesis And Crystal Structure ◽  
Compound C ◽  
Crude Product ◽  
Phenyl Rings

The chemical reaction of dilithiumN,N′-di(tbutyl)-Si,Si-diphenylsilanediamide and PCl3yielded an off-white solid. Sublimation of the crude product under reduced pressure at elevated temperature gave colourless prismatic crystals of the title compound, C20H28ClN2PSi, which crystallizes in the non-centrosymmetric monoclinic space groupCc.The asymmetric unit of the crystal structure contains one molecule and it is dominated by the central SiN2P four-membered ring, which is almost planar with a mean deviation of the atoms from the best plane of 0.014 Å. The angles between the plane defined by the silicon atom and the two nitrogen atoms and the best planes of theSi-phenyl groups are 85.1 (2) and 77.4 (2)°, with the tilt of the phenyl rings in the opposite direction. Bothtert-butyl groups suffer from a two-position rotational disorder with site occupancies of 0.752 (6)/0.248 (6) and 0.878 (9)/0.122 (9). The P—Cl bond [2.2078 (17) Å] is remarkably elongated compared to the P—Cl distance in PCl3[2.034 Å; Galy & Enjalbert (1982).J. Solid State Chem.44, 1–23].

scholarly journals Synthesis and crystal structure of Na4Ni7(AsO4)6

2016 ◽  
Vol 72 (5) ◽  
pp. 632-634 ◽  
Author(s):  
Rénald David
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Monoclinic Space Group ◽  
Site Symmetry ◽  
Asymmetric Unit ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Ceramic Synthesis ◽  
The One

The title compound, tetrasodium heptanickel hexaarsenate, was obtained by ceramic synthesis and crystallizes in the monoclinic space groupC2/m. The asymmetric unit contains seven Ni atoms of which two have site symmetry 2/mand three site symmetry 2, four As atoms of which two have site symmetrymand two site symmetry 2, three Na atoms of which two have site symmetry 2, and fifteen O atoms of which four have site symmetrym. The structure of Na4Ni7(AsO4)6is made of layers of Ni octahedra and As tetrahedra assembled in sheets parallel to thebcplane. These layers are interconnected by corner-sharing between NiO6octahedra and AsO4tetrahedra. This linkage creates tunnels running along thecaxis in which the Na atoms are located. This arrangement is similar to the one observed in Na4Ni7(PO4)6, but the layers of the two compounds are slightly different because of the disorder of one of the Ni sites in the structure of the title compound.

The halotrichite group: the crystal structure of apjohnite

1976 ◽  
Vol 40 (314) ◽  
pp. 599-608 ◽  
Author(s):  
S. Menchetti ◽  
C. Sabelli
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Direct Methods ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
Direct Connection ◽  
Asymmetric Unit ◽  
X Ray ◽  
Bonding System ◽  
Hydrogen Bonding System

SummaryApjohnite, MnAl2(SO4)4·22H2O, is monoclinic, space group P21/c, a 6·198 (2), b 24·347 (4), c 21·266 (4) Å, β 100·28 (3)° and Z = 4. The crystal structure was determined by means of direct methods applied to X-ray data collected with a single-crystal diffractometer. At the end of the refinement, performed with least-squares method, the R index was 0·039.The SO4 tetrahedra, Al(H2O)5 octahedra, and MnO(H2O)5 octahedra are connected by a hydrogen bonding system; the only direct connection between polyhedra is by sharing of an oxygen between S(4) and Mn. In the asymmetric unit there are twenty-two water molecules, five of which lie in channels of the structure and are not linked to the cations but only to ligand water oxygens by means of hydrogen bonds.Powder data indicate a close structural relationship between apjohnite, halotrichite, and pickeringite.

The Crystal Structure of cis-Inositol Monohydrate—Un Objet Retrouvé

1996 ◽  
Vol 49 (3) ◽  
pp. 413 ◽  
Author(s):  
HC Freeman ◽  
DA Langs ◽  
CE Nockolds ◽  
YL Oh
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
High Symmetry ◽  
Asymmetric Unit ◽  
Fourier Methods ◽  
Full Matrix ◽  
Structure Factors ◽  
Independent Molecules

cis-Inositol monohydrate, C6H12O6.H2O, crystallizes in the monoclinic space group P 21/n [a 9.900(8), b 9.296(8), c 17.795(15) Ǻ, β 90.5(1)°, Z 8]. The normalized structure factors Eh have an atypical statistical distribution, and attempts to solve the structure by direct methods (triplet relationships) were unsuccessful. The structure was ultimately solved by Patterson and Fourier methods, and was refined by full-matrix least squares [Rw = 0.047 for 1665 independent reflections ≥2σ(Imin)]. The cis-inositol molecules have approximately trigonal symmetry, as expected. The difficulties encountered during the structure analysis are explained by the presence of two nearly identical molecules of high symmetry in the asymmetric unit. The independent molecules are related by translational pseudosymmetry, and their orientations are such that all the C-C and C-O bonds in the structure are approximately parallel to a small number of directions.

scholarly journals Crystal structure of 7,8,15,16,17-pentathiadispiro[5.2.59.36]heptadecane

2019 ◽  
Vol 75 (6) ◽  
pp. 888-891 ◽  
Author(s):  
Robert Hofstetter ◽  
Benedict J. Elvers ◽  
Felix Potlitz ◽  
Andreas Link ◽  
Carola Schulzke
Keyword(s):  
Crystal Structure ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Related Molecule ◽  
One Dimensional ◽  
Compound C ◽  
The One ◽  
Parallel Fashion ◽  
Cyclohexyl Group

The title compound, C12H20S5, crystallizes in the monoclinic space group P21/c with four molecules in the unit cell. In the crystal, the asymmetric unit comprises the entire molecule with the three cyclic moieties arranged in a line. The molecules in the unit cell pack in a parallel fashion, with their longitudinal axes arranged along a uniform direction. The packing is stabilized by the one-dimensional propagation of non-classical hydrogen-bonding contacts between the central sulfur atom of the S3 fragment and the C—H of a cyclohexyl group from a glide-related molecule [C...S = 3.787 (2) Å].

scholarly journals Crystal structure of a new polymorph of (2S,3S)-2-amino-3-methylpentanoic acid

2018 ◽  
Vol 74 (6) ◽  
pp. 776-779 ◽  
Author(s):  
Sofia Curland ◽  
Elena Meirzadeh ◽  
Yael Diskin-Posner
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Space Group ◽  
Independent Molecules

A new polymorph of (2S,3S)-2-amino-3-methylpentanoic acid, L-isoleucine C6H13NO2, crystallizes in the monoclinic space group P21 with four independent molecules in the asymmetric unit. The molecules are zwitterions. In the crystal, N—H...O hydrogen bonds link two pairs of independent molecules and their symmetry-related counterparts to form two types of layers stacked in an anti-parallel manner parallel to (001). The hydrophobic aliphatic isopropyl groups protrude from these layers.

scholarly journals 5-Amino-1-(2′,3′-O-isopropylidene-D-ribityl)-1H-imidazole-4-carboxamide: a crystal structure withZ′ = 4

2017 ◽  
Vol 73 (2) ◽  
pp. 183-187 ◽  
Author(s):  
Vincenzo Piccialli ◽  
Nicola Borbone ◽  
Giorgia Oliviero ◽  
Gennaro Piccialli ◽  
Stefano D'Errico ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Title Compound ◽  
Monoclinic Space Group ◽  
Intermolecular Hydrogen Bonding ◽  
Asymmetric Unit ◽  
Compound C ◽  
Independent Molecules ◽  
Intramolecular Hydrogen ◽  
Similar Conformation

The title compound, C12H20N4O5, crystallizes in the monoclinic space groupP21, with four crystallographically independent molecules in the asymmetric unit. The four molecules have a very similar conformation that is basically determined by the formation of two intramolecular hydrogen bonds between the amino NH2donors and the carbonyl and ring O-atom acceptors, forming, respectively,R(6) andR(7) ring motifs.. In the crystal, intermolecular hydrogen bonding leads to the formation ofR22(10) ring patterns, involving one amide CONH2donor and an imidazole N-atom acceptor. The cluster of the four independent molecules has approximate non-crystallographicC2point symmetry. The structural analysis also shows that during the synthesis of the title compound, the reductive cleavage of the D-ribose ring of the inosine precursor proceeds stereoselectively, with retention of configuration.

scholarly journals Crystal structure of (R,S)-2-hydroxy-4-(methylsulfanyl)butanoic acid

2020 ◽  
Vol 76 (4) ◽  
pp. 562-566
Author(s):  
Thomas P. Mawhinney ◽  
Yiyi Li ◽  
Deborah L. Chance ◽  
Steven P. Kelley ◽  
Valeri V. Mossine
Keyword(s):  
Crystal Structure ◽  
Significant Contribution ◽  
Animal Feed ◽  
Hirshfeld Surface ◽  
Monoclinic Space Group ◽  
Monomeric Form ◽  
Asymmetric Unit ◽  
Feed Supplement ◽  
Butanoic Acid ◽  
Compound A

The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called DL-methionine hydroxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form. The melting point is 302.5 K and the compound crystallizes in the monoclinic space group P21/c, with two conformationally non-equivalent molecules [(I A ) and (I B )] in the asymmetric unit. The crystal structure is formed by alternating polar and non-polar layers running along the bc plane and features an extensive hydrogen-bonding network within the polar layers. The Hirshfeld surface analysis revealed a significant contribution of non-polar H...H and H...S interactions to the packing forces for both molecules.

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