Space Group P21 (space + group_p21)

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Space Group P21

  • monoclinic space group p21
  • primitive monoclinic space group p21


  • Selected Abstracts


    Synthesis and crystal structure investigation of pyridine-2-(3,-mercaptopropanoic acid)- N -oxide

    CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2007
    R. Ramasubramanian
    Abstract Pyridine-2-(3,-mercaptopropanoic acid)- N -oxide (I), is a higher homologue of 1-oxopyridinium-2-thioacetic acid (II) [1]. It crystallizes in monoclinic space group P21 with a = 9.2168(2) Å, b = 4.1423(2) Å, c = 11.3904(4) Å, , = 98.65(2)°, V = 429.93(3) Å3 and Z = 2. The least-squares refinement gave residual index R = 0.024 for 1070 observed reflections. The introduction of an additional methylene group in (II) causes a flip in the carboxylic acid group of (I) that facilitates the molecules to align infinite antiparallel chains through strong C,H···O interactions. The molecules are interlinked by O,H···O hydrogen bonding across the chains and forming an infinite screw chain along y-direction. The molecular packing is stabilized by O,H···O and C,H···O hydrogen bonding and ,-, electron interactions. This is an important facet of the crystal packing. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    New Organic Nonlinear Optical Polyene Crystals and Their Unusual Phase Transitions,

    ADVANCED FUNCTIONAL MATERIALS, Issue 11 2007
    O-P. Kwon
    Abstract A series of new nonlinear optical chromophores based on configurationally locked polyenes (CLPs) with chiral pyrrolidine donors are synthesized. All CLP derivatives exhibit high thermal stability with decomposition temperatures Td at least > ,270,°C. Acentric single crystals of enantiopure D - and L -prolinol-based chromophores with a monoclinic space group P21 exhibit a macroscopic second-order nonlinearity that is twice as large than that of analogous dimethylamino-based crystal. This is attributed to a strong hydrogen-bonded polar polymer-like chain built by these molecules, which is aligned along the polar crystallographic b -axis. Five ,-phase CLP crystals with different donors grown from solution exhibit a reversible or irreversible thermally induced structural phase transition to a ,-phase. These phase transitions are unusual, changing the crystal symmetry from higher to lower at increasing temperatures, for example, from centrosymmetric to non-centrosymmetric, enhancing their macroscopic second-order nonlinear optical properties. [source]


    Guest-Induced Chirality in the Ferrimagnetic Nanoporous Diamond Framework Mn3(HCOO)6,

    ADVANCED FUNCTIONAL MATERIALS, Issue 4 2007
    B. Zhang
    Abstract Chiral magnets are obtained by inclusion of chiral guest molecules into the channels of an achiral nanoporous ferrimagnet consisting of the Mn3(HCOO)6 (1) framework. Insertion of the R or the S enantiomer of 2-chloropropan-1-ol (CH3C*HClCH2OH) in the chiral pores of the previously emptied framework (space group P21/c) results in the two corresponding chiral solids (1R and 1S, space group P21), while insertion of a racemic mixture of the two enantiomers retains the achirality of the host for the meso solid (1RS, space group P21/c). The R guest is ordered in the M channels while the S guest is ordered in the P channels. In contrast, the R guests in the P channels and the S guests in the M channels are disordered on two crystallographic orientations. For the racemic mixture of the two enantiomers in 1RS, random disorder of guests in both channels is observed. Thus, the localization of the guest molecule depends on the nature of the surface to recognize the guest of a particular chirality. The guest inclusion compounds are thermally stable. The 1R and 1S compounds are optically active. All the compounds adopt a ferrimagnetic ground state. Compared to the host framework of 1 without guest, the Curie temperature decreases for both 1R and 1S but increases for 1RS. The additional interactions between the framework and the inserted guest alcohols strengthen the lattice via hydrogen bonds and other electrostatic forces, and it might account for the significant lowering of the lattice contribution as well as the magnetic component to the specific heat capacity upon guest loading. [source]


    Zinc Vanadates in Vanadium Oxide-Doped Zinc Oxide Varistors

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001
    Huey-Hoon Hng
    Convergent-beam electron diffraction has been used to determine the space groups of ,- and ,-Zn3(VO4)2 particles in vanadium oxide-doped zinc oxide varistors. The crystal structure of ,-Zn3(VO4)2 has been determined to be monoclinic with space group P21 and lattice parameters of a= 9.80 Å, b= 8.34 Å, c= 10.27 Å, and ,= 115.8°, whereas that of ,-Zn3(VO4)2 is monoclinic with space group Cm and a= 10.40 Å, b= 8.59 Å, c= 9.44 Å, and ,= 98.8°. Energy-dispersive X-ray microanalysis of these two phases shows significant deviations from their expected stoichiometry. It is apparent that the ,-phase is, in fact, the metastable Zn4V2O9 phase, whereas the ,-phase either is a new oxide that consists of zinc, vanadium, and manganese or, more likely, is a zinc vanadate phase with a Zn:V atomic ratio of 1:1 that has the ability to go into solid solution with manganese. [source]


    Structures of the OmpF porin crystallized in the presence of foscholine-12

    PROTEIN SCIENCE, Issue 5 2010
    Georgia Kefala
    Abstract The endogenous Escherichia coli porin OmpF was crystallized as an accidental by-product of our efforts to express, purify, and crystallize the E. coli integral membrane protein KdpD in the presence of foscholine-12 (FC12). FC12 is widely used in membrane protein studies, but no crystal structure of a protein that was both purified and crystallized with this detergent has been reported in the Protein Data Bank. Crystallization screening for KdpD yielded two different crystals of contaminating protein OmpF. Here, we report two OmpF structures, the first membrane protein crystal structures for which extraction, purification, and crystallization were done exclusively with FC12. The first structure was refined in space group P21 with cell parameters a = 136.7 Å, b = 210.5 Å, c = 137 Å, and , = 100.5°, and the resolution of 3.8 Å. The second structure was solved at the resolution of 4.4 Å and was refined in the P321 space group, with unit cell parameters a = 215.5 Å, b = 215.5 Å, c = 137.5 Å, and , = 120°. Both crystal forms show novel crystal packing, in which the building block is a tetrahedral arrangement of four trimers. Additionally, we discuss the use of FC12 for membrane protein crystallization and structure determination, as well as the problem of the OmpF contamination for membrane proteins overexpressed in E. coli. [source]


    Isomeric N -(iodophenyl)nitrobenzamides form different three-dimensional framework structures

    ACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2006
    James L. Wardell
    The isomeric N -(iodophenyl)nitrobenzamides, C13H9IN2O3, all form different three-dimensional framework structures. Molecules of N -(2-iodophenyl)-3-nitrobenzamide (II) are linked by a combination of N,H,O and C,H,O hydrogen bonds and a two-centre iodo,carbonyl interaction. The supramolecular structure of N -(2-iodophenyl)-4-nitrobenzamide (III) is built from one N,H,O and two C,H,O hydrogen bonds, but short I,O contacts are absent from the structure. In N -(3-iodophenyl)-2-nitrobenzamide (IV), which crystallizes with Z, = 2 in space group P21, the structure contains two N,H,O hydrogen bonds, four C,H,O hydrogen bonds, two two-centre iodo,nitro interactions and an aromatic ,,, stacking interaction. The structure of N -(3-iodophenyl)-3-nitrobenzamide (V) contains one N,H,O hydrogen bond and three C,H,O hydrogen bonds, together with a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, while in N -(3-iodophenyl)-4-nitrobenzamide (VI), the combination of one N,H,O hydrogen bond and two C,H,O hydrogen bonds is augmented not only by a two-centre iodo,nitro interaction and an aromatic ,,, stacking interaction, but also by a dipolar carbonyl,carbonyl interaction. In the supramolecular structure of N -(4-iodophenyl)-4-nitrobenzamide (IX), which crystallizes with Z, = 2 in space group , there are two N,H,O hydrogen bonds, four C,H,O hydrogen bonds and two three-centre iodo,nitro interactions. [source]


    Topochemically controlled solid-state methyl ­rearrangement in thiocyanurates

    ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2001
    Mark Greenberg
    4,6-Dimethoxy-3-methyl-1,3,5-triazine-2(3H)-thione crystallizes in two polymorphic forms, needles and plates. In the needle-shaped crystals (9a) the molecules occupy the crystallographic mirror plane, thus the layers are stacked along the b axis. The molecules of the other polymorph [plate-shape crystals, (9b)] are packed in a herringbone packing mode. Upon heating, (9b) undergoes a phase transition to form (9a). At 378,K the needles undergo O , S topochemically controlled methyl transfer in the solid state to produce 1-methyl-4-methoxy-6-methylthio-1,3,5-triazine-2(1H)-one in 75% yield. The enthalpy of the rearrangement is estimated to be ,39.1,kJ,mol,1. 1-Methyl-6-methoxy-4-methylthio-1,3,5-triazine-2(1H)-thione crystallizes in space group P21 with two crystallographically independent molecules in the asymmetric unit. Compound (9b) undergoes O , S methyl transfer in the solid state at 373,K. The rearrangement is topochemically assisted and the product, 1-methyl-2,4-bismethylthio-1,3,5-triazine-6(1H)-one, is obtained in quantitative yield. The enthalpy of the rearrangement is estimated to be ,58.8,kJ,mol,1. The crystal structures of the compounds as well as their DSC thermographs are described and discussed. Energy calculation by ab initio methods shows that the driving force for the reactions is the difference between the molecular energies of the pre-rearranged compounds and their products, 54.2 and 59.3,kJ,mol,1 in the two cases, respectively. [source]


    Hydrogen-bonded dimers, chains and rings in six differently substituted 2-vinyltetrahydro-1,4-epoxy-1-benzazepines

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010
    Lina M. Acosta
    In (2SR,4RS)-2- exo -vinyl-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C12H13NO, (I), the molecules are linked by two independent C,H...,(arene) hydrogen bonds to form sheets, such that all of the molecules in a given sheet are of the same configuration. The molecules of (2SR,4RS)-7-chloro-2- exo -(2-methylprop-1-enyl)-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C14H16ClNO, (II), are linked by a C,H...O hydrogen bond into C(4) chains, where all the molecules in a given chain are of the same configuration, whereas the molecules of (2SR,4RS)-8-chloro-9-methyl-2- exo -(2-methylprop-1-enyl)-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C15H18ClNO, (III), are linked into centrosymmetric dimers by pairs of symmetry-related C,H...,(arene) hydrogen bonds. (2RS,4RS)-8-Chloro-9-methyl-2- endo -(2-methylprop-1-enyl)-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C15H18ClNO, (IV), is a diastereoisomer of (III) and, as for (II), a single C,H...O hydrogen bond links the molecules into C(4) chains, each containing molecules of a single configuration. The structure of (2SR,4RS)-8-chloro-9-methyl-2- exo -(prop-1-en-2-yl)-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C14H16ClNO, (V), contains a C,H...O hydrogen bond which links pairs of molecules into centrosymmetric R22(6) dimers. (2SR,4RS)-7,9-Dichloro-2- exo -(prop-1-en-2-yl)-2,3,4,5-tetrahydro-1H -1,4-epoxy-1-benzazepine, C13H13Cl2NO, (VI), is an inversion twin containing both the (2S,4R) and (2R,4S) enantiomers in the space group P21, and a C,H...O hydrogen bond links molecules of a given configuration into simple C(3) chains. [source]


    Eight 7-benzyl-3- tert -butyl-1-phenylpyrazolo[3,4- d]oxazines, encompassing structures containing no intermolecular hydrogen bonds, and hydrogen-bonded structures in one, two or three dimensions

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009
    Juan C. Castillo
    7-Benzyl-3- tert -butyl-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C22H25N3O, (I), and 3- tert -butyl-7-(4-methylbenzyl)-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C23H27N3O, (II), are isomorphous in the space group P21, and molecules are linked into chains by C,H...O hydrogen bonds. In each of 3- tert -butyl-7-(4-methoxybenzyl)-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C23H27N3O2, (III), which has cell dimensions rather similar to those of (I) and (II), also in P21, and 3- tert -butyl-1-phenyl-7-[4-(trifluoromethyl)benzyl]-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C23H24F3N3O, (IV), there are no direction-specific interactions between the molecules. In 3- tert -butyl-7-(4-nitrobenzyl)-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C22H24N4O3, (V), a combination of C,H...O and C,H...N hydrogen bonds links the molecules into complex sheets. There are no direction-specific interactions between the molecules of 3- tert -butyl-7-(2,3-dimethoxybenzyl)-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C24H29N3O3, (VI), but a three-dimensional framework is formed in 3- tert -butyl-7-(3,4-methylenedioxybenzyl)-1-phenyl-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C23H25N3O3, (VII), by a combination of C,H...O, C,H...N and C,H...,(arene) hydrogen bonds, while a combination of C,H...O and C,H...,(arene) hydrogen bonds links the molecules of 3- tert -butyl-1-phenyl-7-(3,4,5-trimethoxybenzyl)-6,7-dihydro-1H,4H -pyrazolo[3,4- d][1,3]oxazine, C25H31N3O4, (VIII), into complex sheets. In each compound, the oxazine ring adopts a half-chair conformation, while the orientations of the pendent phenyl and tert -butyl substituents relative to the pyrazolo[3,4- d]oxazine unit are all very similar. [source]


    Coordination behaviour and two-dimensional-network formation in poly[[,-aqua-diaqua(,5 -propane-1,3-diyldinitrilotetraacetato)dilithium(I)cobalt(II)] dihydrate]: the first example of an MII,1,3-pdta complex with a monovalent metal counter-ion

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2008
    Urszula Rychlewska
    The title compound, {[CoLi2(C11H14N2O8)(H2O)3]·2H2O}n, constitutes the first example of a salt of the [MII(1,3-pdta)]2, complex (1,3-pdta is propane-1,3-diyldinitrilotetraacetate) with a monopositive cation as counter-ion. Insertion of the Li+ cation could only be achieved through application of the ion-exchange column technique which, however, appeared unsuccessful with other alkali metals and the ammonium cation. The structure contains two tetrahedrally coordinated Li+ cations, an octahedral [Co(1,3-pdta)]2, anion and five water molecules, two of which are uncoordinated, and is built of two-dimensional layers extending parallel to the (010) lattice plane, the constituents of which are connected by the coordinate bonds. O,Hwater...O hydrogen bonds operate both within and between these layers. The crystal investigated belongs to the enantiomeric space group P21 with only one (,) of two possible optical isomers of the [Co(1,3-pdta)]2, complex. A possible cause of enantiomer separation during crystallization might be the rigidification and polarization of the [M(1,3-pdta)]2, core, resulting from direct coordination of Li+ cations to three out of four carboxylate groups constituting the 1,3-pdta ligand. The structure of (I) differs considerably from those of the other [MII(1,3-pdta)]2, complexes, in which the charge compensation is realized by means of divalent hexaaqua complex cations. This finding demonstrates a significant structure-determining role of the counter-ions. [source]


    N -(2-Carboxy­benzoyl)- l -leucine methyl ester

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2006
    Alvaro B. Onofrio
    The title compound (with the systematic name 2-{[(1S)-1-(methoxy­carbonyl)-3-methyl­butyl]amino­carbonyl}benzoic acid), C15H19NO5, crystallizes in the monoclinic space group P21, with two independent mol­ecules per asymmetric unit. The most notable difference between the two mol­ecules is in the dihedral angles between the planes of the carboxyl group and the benzene ring, which are 3.5,(3) and 25.7,(1)°. This difference may account for the fact that two competing reactions are observed in aqueous solution, namely cyclization to form the imide N -phthaloyl­leucine and hydrolysis of N -(2-carboxy­benzoyl)- l -leucine methyl ester to phthalic acid and leucine. [source]


    Two new non-centrosymmetric lithium salts of glycine: bis(glycine) lithium chromate monohydrate and bis(glycine) lithium molybdate

    ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2006
    Michel Fleck
    In bis­(glycine) lithium chromate monohydrate {systematic name: poly[aquadi-,-glycinato-,-tetra­oxochromato(VI)-dilithium(I)]}, [CrLi2(C2H5NO2)2O4(H2O)]n, (I) (space group P212121), and bis­(glycine) lithium molybdate {systematic name: poly[di-,-glycinato-,-tetra­oxomolybdato(VI)-dilithium(I)]}, [Li2Mo(C2H5NO2)2O4]n, (II) (space group P21), all atoms are located on general positions. The crystal structure of (I) is characterized by infinite chains of corner-sharing [LiO4] tetra­hedra, which are connected by glycine mol­ecules to form layers. [CrO4] tetra­hedra are attached to the [LiO4] tetra­hedra. Compound (II) contains dimers of [LiO4] tetra­hedra which are connected by [MoO4] tetra­hedra to form chains, which are in turn connected by glycine mol­ecules to form double layers. [source]


    Two crystal modifications of (Pro-Pro-Gly)4 -Hyp-Hyp-Gly-(Pro-Pro-Gly)4 reveal the puckering preference of Hyp(X) in the Hyp(X):Hyp(Y) and Hyp(X):Pro(Y) stacking pairs in collagen helices

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2010
    Kenji Okuyama
    Two crystal modifications of a collagen model peptide, (Pro-Pro-Gly)4 -Hyp-Hyp-Gly-(Pro-Pro-Gly)4 [where Hyp is (4R,2S)- l -hydroxyproline], showed very similar unit-cell parameters and belonged to the same space group P21. Both crystals exhibited pseudo-merohedral twinning. The main difference was in their molecular-packing arrangements. One modification showed pseudo-hexagonal packing, while the other showed pseudo-tetragonal packing. Despite their different packing arrangements, no significant differences were observed in the hydration states of these modifications. The peptide in the pseudo-tetragonal crystal showed a cyclic fluctuation of helical twists with a period of 20,Å, while that in the pseudo-hexagonal crystal did not. In these modifications, the puckering conformations of four of the 12 Hyp residues at the X position of the Hyp(X)-Hyp(Y)-Gly sequence were in the opposite conformations to the previous hypothesis that Hyp(X) residues involved in Hyp(X):Hyp(Y) and Hyp(X):Pro(Y) stacking pairs prefer up-puckering and down-puckering conformations, respectively. Detailed investigation of the molecular interactions between Hyp(X) and adjacent molecules revealed that these opposite conformations appeared because the puckering conformation, which follows the hypothesis, is subject to steric hindrance from the adjacent molecule. [source]


    A case of structure determination using pseudosymmetry

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2009
    Sergei Radaev
    Here, a case is presented of an unusual structure determination which was facilitated by the use of pseudosymmetry. Group A streptococcus uses cysteine protease Mac-1 (also known as IdeS) to evade the host immune system. Native Mac-1 was crystallized in the orthorhombic space group P21212. Surprisingly, crystals of the inactive C94A mutant of Mac-1 displayed monoclinic symmetry with space group P21, despite the use of native orthorhombic Mac-1 microcrystals for seeding. Attempts to solve the structure of the C94A mutant by MAD phasing in the monoclinic space group did not produce an interpretable map. The native Patterson map of the C94A mutant showed two strong peaks along the (1 0 1) diagonal, indicating possible translational pseudosymmetry in space group P21. Interestingly, one-third of the monoclinic reflections obeyed pseudo-orthorhombic P21212 symmetry similar to that of the wild-type crystals and could be indexed and processed in this space group. The pseudo-orthorhombic and monoclinic unit cells were related by the following vector operations: am = bo,co, bm = ao and cm = ,2co,bo. The pseudo-orthorhombic subset of data produced good SAD phases, leading to structure determination with one monomer in the asymmetric unit. Subsequently, the structure of the Mac-1 mutant in the monoclinic form was determined by molecular replacement, which showed six molecules forming three translationally related dimers aligned along the (1 0 1) diagonal. Knowing the geometric relationship between the pseudo-orthorhombic and the monoclinic unit cells, all six molecules can be generated in the monoclinic unit cell directly without the use of molecular replacement. The current case provides a successful example of the use of pseudosymmetry as a powerful phase-averaging method for structure determination by anomalous diffraction techniques. In particular, a structure can be solved in a higher pseudosymmetry subcell in which an NCS operator becomes a crystallographic operator. The geometrical relationships between the subcell and parental cell can be used to generate a complete molecular representation of the parental asymmetric unit for refinement. [source]


    A new crystal form of human tear lipocalin reveals high flexibility in the loop region and induced fit in the ligand cavity

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2009
    Daniel A. Breustedt
    Tear lipocalin (TLC) with the bound artificial ligand 1,4-butanediol has been crystallized in space group P21 with four protein molecules in the asymmetric unit and its X-ray structure has been solved at 2.6,Å resolution. TLC is a member of the lipocalin family that binds ligands with diverse chemical structures, such as fatty acids, phospholipids and cholesterol as well as microbial siderophores and the antibiotic rifampin. Previous X-ray structural analysis of apo TLC crystallized in space group C2 revealed a rather large bifurcated ligand pocket and a partially disordered loop region at the entrace to the cavity. Analysis of the P21 crystal form uncovered major conformational changes (i) in ,-strands B, C and D, (ii) in loops 1, 2 and 4 at the open end of the ,-barrel and (iii) in the extended C-terminal segment, which is attached to the ,-barrel via a disulfide bridge. The structural comparison indicates high conformational plasticity of the loop region as well as of deeper parts of the ligand pocket, thus allowing adaptation to ligands that differ vastly in size and shape. This illustrates a mechanism for promiscuity in ligand recognition which may also be relevant for some other physiologically important members of the lipocalin protein family. [source]


    Imperfect pseudo-merohedral twinning in crystals of fungal fatty acid synthase

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2009
    Simon Jenni
    The recent high-resolution structures of fungal fatty acid synthase (FAS) have provided new insights into the principles of fatty acid biosynthesis by large multifunctional enzymes. The crystallographic phase problem for the 2.6,MDa fungal FAS was initially solved to 5,Å resolution using two crystal forms from Thermomyces lanuginosus. Monoclinic crystals in space group P21 were obtained from orthorhombic crystals in space group P212121 by dehydration. Here, it is shown how this space-group transition induced imperfect pseudo-merohedral twinning in the monoclinic crystal, giving rise to a Moiré pattern-like interference of the two twin-related reciprocal lattices. The strategy for processing the twinned diffraction images and obtaining a quantitative analysis is presented. The twinning is also related to the packing of the molecules in the two crystal forms, which was derived from self-rotation function analysis and molecular-replacement solutions using a low-resolution electron microscopy map as a search model. [source]


    Structure of a d(TGGGGT) quadruplex crystallized in the presence of Li+ ions

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2007
    Christophe Creze
    A parallel 5,-d(TGGGGT)-3, quadruplex was formed in Na+ solution and crystallized using lithium sulfate as the main precipitating agent. The X-ray structure was determined to 1.5,Å resolution in space group P21 by molecular replacement. The asymmetric unit consists of a characteristic motif of two quadruplexes stacked at their 5, ends. All nucleotides are clearly defined in the density and could be positioned. A single bound Li+ ion is observed at the surface of the column formed by the two joined molecules. Thus, this small alkali metal ion appears to be unsuitable as a replacement for the Na+ ion in the central channel of G-quartets, unlike K+ or Tl+ ions. A well conserved constellation of water molecules is observed in the grooves of the dimeric structure. [source]


    Expression, crystallization and preliminary X-ray crystallographic studies of Klebsiella pneumoniae maltohexaose-producing ,-amylase

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 12-2 2004
    Mitsuru Momma
    A recombinant form of Klebsiella pneumoniae maltohexaose-producing ,-amylase has been overexpressed in Escherichia coli and purified to homogeneity. Crystals were obtained at 293,K by the microbatch technique using 80,mM sodium/potassium phosphate buffer pH 6.2 containing 8% polyethylene glycol 3000, 4% polyethylene glycol 3350 and 40,mM sodium thiocyanate. Crystals of the overexpressed recombinant enzyme diffracted to better than 2.5,Å resolution at 95,K using a synchrotron-radiation source. The crystals belong to the primitive monoclinic space group P21, with unit-cell parameters a = 74.8, b = 107.6, c = 82.2,Å, , = 96.2°. Assuming the presence of two molecules per asymmetric unit, the VM value for the crystal was 2.3,Å3,Da,1, indicating a solvent content of 47%. [source]


    Crystallization and preliminary X-ray crystallographic analysis of the laminarinase endo-,-1,3-glucanase from Pyrococcus furiosus

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 12-2 2004
    Andrea Ilari
    Laminarinase endo-,-1,3 glucanase (LamA) from Pyrococcus furiosus is an enzyme which displays its main hydrolytic activity on the ,-1,3-glucose polymer laminarin. This laminarinase is remarkably resistant to denaturation: its secondary structure is unchanged in 8,M guanidinium chloride. This protein belongs to the family 16 glycosyl hydrolases, which are enzymes that are widely distributed among bacteria, fungi and higher plants. Single crystals of P. furiosus LamA have been obtained by the hanging-drop vapour-diffusion method using 2-­methyl-2,4-pentanediol as a precipitant agent. A complete data set has been collected under cryocooling at a synchrotron source. The crystals belong to the monoclinic space group P21, with unit-cell parameters a = 44.36, b = 84.76, c = 69.23,Å, , = 90, , = 104.97, , = 90°, and diffract to 2.15,Å resolution. [source]


    Crystallization and preliminary X-ray crystallographic studies of mouse autocrine motility factor

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2004
    Noriko Naba
    Mouse autocrine motility factor (mAMF), a tumour-secreted cytokine that stimulates cell migration in vitro and metastasis in vivo, has been crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the monoclinic space group P21, with unit-cell parameters a = 69.97, b = 115.88, c = 73.27,Å, , = 101.76°. There are two subunits (one dimer) per asymmetric unit. Complexes with four-, five- and six-carbon carbohydrate phosphate inhibitors have also been crystallized. The crystals diffract to at least 1.8,Å resolution and are suitable for X-ray structure analyses at high resolution. [source]


    Crystallization and preliminary X-ray analysis of a C-terminal TonB fragment from Escherichia coli

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2004
    Jiri Koedding
    The TonB protein located in the cell wall of Gram-negative bacteria mediates the proton motive force from the cytoplasmic membrane to specific outer membrane transporters. A C-terminal fragment of TonB from Escherichia coli consisting of amino-acid residues 147,239 (TonB-92) has been purified and crystallized. Crystals grew in space group P21 to dimensions of about 1.0 × 0.12 × 0.12,mm. A native data set has been obtained to 1.09,Å resolution. [source]


    Crystallization and preliminary X-ray crystallographic analyses of CMY-1 and CMY-10, plasmidic class C ,-lactamases with extended substrate spectrum

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004
    Sun-Joo Lee
    Plasmid-encoded class C ,-lactamases, including CMY-1 and CMY-­10, hydrolyze the lactam bonds of ,-lactam antibiotics, inducing therapeutic failure and a lack of eradication of clinical isolates by third-generation cephalosporins or cephamycins. Therefore, the enzymes are potential targets for developing agents against pathogens isolated from patients suffering from wound infection, urinary tract infection or pneumonia. CMY-1 and CMY-10 were purified and crystallized at 298,K. X-ray diffraction data from CMY-1 and CMY-­10 crystals have been collected to 2.5 and 1.5,Å resolution, respectively, using synchrotron radiation. The crystals of the two proteins are isomorphous and belong to the primitive monoclinic space group P21. [source]


    Structural comparison of Escherichia colil -asparaginase in two monoclinic space groups

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2003
    Mario Sanches
    The functional l -asparaginase from Escherichia coli is a homotetramer with a molecular weight of about 142,kDa. The X-ray structure of the enzyme, crystallized in a new form (space group C2) and refined to 1.95,Å resolution, is compared with that of the previously determined crystal form (space group P21). The asymmetric unit of the new crystal form contains an l -asparaginase dimer instead of the tetramer found in the previous crystal form. It is found that crystal contacts practically do not affect the conformation of the protein. It is shown that subunit C of the tetrameric form is in a conformation which is systematically different from that of all other subunits in both crystal forms. Major conformational differences are confined to the lid loop (residues 14,27). In addition, the stability of this globular protein is analyzed in terms of the interactions between hydrophobic parts of the subunits. [source]


    Crystallization and preliminary X-ray diffraction studies of the water-soluble state of the pore-forming toxin sticholysin II from the sea anemone Stichodactyla helianthus

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2002
    José M. Mancheño
    Sticholysin II (StnII) is a potent cytolytic protein produced by the sea anemone Stichodactyla helianthus. StnII belongs to the actinoporin family, a group of proteins which are characterized by their ability to spontaneously interact with biological membranes. The cytolytic character of these proteins is currently explained in terms of a molecular mechanism involving the formation of transmembrane pores. StnII has been crystallized using the hanging-drop vapour-diffusion method at 291,K. Diffraction-quality crystals have unit-cell parameters a = 32.30, b = 119.73, c = 43.42,Å, , = 90.04° and belong to the monoclinic space group P21. Diffraction data to a resolution of 1.71,Å were collected at synchrotron facilities. [source]


    Crystallization and preliminary X-ray data of the recombinant peptide amidase from Stenotrophomonas maltophilia

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2002
    Sebastian Neumann
    The peptide amidase from Stenotrophomonas maltophilia selectively hydrolyses the C-terminal amide bond in peptide amides. Crystals have been obtained by sitting-drop vapour diffusion from solution containing polyethylene glycol (PEG) 6000, HEPES pH 7.5, glycerine and sodium azide (NaN3). The crystals belong to the monoclinic space group P21, with unit-cell parameters a = 74.18, b = 62.60, c = 101.91,Å, , = 90°. X-ray data from these crystals diffracted at the European Synchrotron Radiation Facility (ESRF, France) ID14-1 beamline to 1.4,Å. [source]


    Crystallization and preliminary X-ray crystallographic studies of a mutant of ribosome recycling factor from Escherichia coli, Arg132Gly

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2002
    Hiroaki Nakano
    Ribosome recycling factor (RRF) plays a central role during the recycling of ribosomes in the final step of protein biosynthesis in prokaryotes and is therefore a favourable target for the development of new antibiotics. The crystal structure of Escherichia coli RRF has been reported to have an open L-shaped conformation, while other RRFs from thermophilic bacteria have a strict L-shaped conformation [Yun et al. (2000), Acta Cryst. D56, 84,85]. Wild-type E. coli RRF has so far not been crystallized free from bound detergent. Here, a mutant of RRF, Arg132Gly, has been crystallized without any detergent. A complete data set from a crystal of this mutant obtained by the hanging-drop vapour-diffusion method has been collected at 2.2,Å resolution using synchrotron radiation at 100,K. The crystal belongs to the monoclinic space group P21, with unit-cell parameters a = 46.02, b = 49.27, c = 49.37,Å, , = 110.1°. The currently refined structure indicates that RRF has a tRNA-like L-­shaped conformation. [source]


    Crystallization and preliminary X-ray analysis of clade I catalases from Pseudomonas syringae and Listeria seeligeri

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2001
    Xavier Carpena
    Haem-containing catalases are homotetrameric molecules that degrade hydrogen peroxide. Phylogenetically, the haem-containing catalases can be grouped into three main lines or clades. The crystal structures of seven catalases have been determined, all from clades II and III. In order to obtain a structure of an enzyme from clade I, which includes all plant, algae and some bacterial enzymes, two bacterial catalases, CatF from Pseudomonas syringae and Kat from Listeria seeligeri, have been crystallized by the hanging-drop vapour-diffusion technique, using PEG and ammonium sulfate as precipitants, respectively. Crystals of P. syringae CatF, with a plate-like morphology, belong to the monoclinic space group P21, with unit-cell parameters a = 60.6, b = 153.9, c = 109.2,Å, , = 102.8°. From these crystals a diffraction data set to 1.8,Å resolution with 98% completeness was collected using synchrotron radiation. Crystals of L. seeligeri Kat, with a well developed bipyramidal morphology, belong to space group I222 (or I212121), with unit-cell parameters a = 74.4, b = 121.3, c = 368.5,Å. These crystals diffracted beyond 2.2,Å resolution when using synchrotron radiation, but presented anisotropic diffraction, with the weakest direction perpendicular to the long c axis. [source]


    Crystallization and preliminary X-ray crystallographic studies on the bacteriophage ,6 RNA-dependent RNA polymerase

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2000
    Sarah J. Butcher
    The RNA-dependent RNA polymerase (P2) from bacteriophage ,6 has been cloned and the protein overexpressed in Escherichia coli to produce an active enzyme. A fully substituted selenomethionyl version of the protein has also been produced. Crystals of both proteins have been grown; most belong to the monoclinic space group P21, with unit-cell parameters a = 105.9, b = 94.0, c = 140.9,Å, , = 101.4°, but some are trigonal (space group P31 or P32), with unit-cell parameters a = b = 110.1, c = 159.4,Å, , = 120°. Both crystal forms occur in the same crystallization drop and are morphologically indistinguishable. Native data sets have been collected from both types of crystals to better than 3,Å resolution. [source]


    Crystallization and preliminary X-ray diffraction studies of phospholipase D from Streptomyces sp.

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2000
    Ingar Leiros
    Crystals of purified phospholipase D (E.C. 3.1.4.4) from Streptomyces sp. strain PMF have been grown under two different crystallization conditions using vapour diffusion. Both conditions gave monoclinic crystals in space group P21. The unit-cell parameters were a = 57.28, b = 57.42, c = 68.70,Å, , = 93.17°. The crystals diffract at 110,K to a resolution beyond 1.4,Å using synchrotron radiation. [source]


    Purification, crystallization and X-ray analysis of crystals of pectate lyase A from Erwinia chrysanthemi

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2000
    Chuong N. Doan
    Pectate lyase A is secreted by Erwinia chrysanthemi and is a virulence factor for soft rot diseases in plants. Crystals of pectate lyase A were obtained by vapor-diffusion techniques in the presence of polyethylene glycol. The crystals belong to the monoclinic space group P21, with unit-cell parameters a = 48.96, b = 148.86, c = 78.61,Å, , = 97.32°. The crystals contain two protein molecules of 38,kDa per asymmetric unit and diffract to 2.4,Å using Cu,K, radiation. [source]