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PubMed1989

Human plasminogen kringle 4. Crystallization and preliminary diffraction data of two different crystal forms.

Human plasminogen kringle 4 has been crystallized in two different crystal forms: monoclinic, a = 32.78(3), b = 49.17(2), c = 46.27(3) A, beta = 100.67 degrees, space group P2(1), four molecules/unit cell, two molecules/asymmetric unit; orthorhombic, a = 32.09(7), b = 49.14(6), c = 49.47(9) A, space group P2(1)2(1)2, four molecules/unit cell. Both crystal forms have a large protein fraction (66% for monoclinic and 62% for orthorhombic) and diffract x-rays to 2.0 A resolution. A self-rotation function has been calculated with monoclinic data indicating a non-crystallographic 2-fold rotation approximately parallel to a* (peak height of 14.3 x sigma). Cross-rotation function calculations are in progress utilizing the coordinates of the conserved structure of kringle 1 of prothrombin and plasminogen kringle 4.

Crystallization↗
PubMed1988

Crystallization and preliminary X-ray diffraction studies of a toxic crystal protein from a subspecies of Bacillus thuringiensis.

The toxic crystal protein (Mr 64,000) from a subspecies of the bacterium Bacillus thuringiensis has been solubilized and recrystallized yielding diffraction quality crystals. Crystals are obtained by a change in pH and ionic strength using Na2CO3. They can also be obtained by a change in ionic strength only using NaBr as the precipitant. The space group of both forms is C222(1) with a = 133, b = 116, c = 104 A and one molecule/asymmetric unit. Still photographs show reflections to 3.0-A resolution.

Bacillus thuringiensis↗
PubMed1981

Correlation between crystal habit and the composition of solvated and nonsolvated cholesterol crystals.

The correlation between the crystal habit and the composition of cholesterol crystals formed in four organic solvents (methanol, acetonitrile, ethanol, and acetone) was studied. Anhydrous and monohydrate cholesterol were precipitated in anhydrous and aqueous organic solvent mixtures, respectively. The main conclusions derived from the study were that 1) the appearance of plates does not automatically guarantee the presence of hydrated cholesterol, and 2) the presence of 5% or more of water in the crystallization solvent may not results in the formation of monohydrate cholesterol.

Acetone↗
PubMed1999

Enantioselective Single-Crystal-to-Single-Crystal Photodimerization of Coumarin and Thiocoumarin in Inclusion Complexes with Chiral Host Compounds.

An intermolecular enantioselective photoreaction by a single-crystal-to-single-crystal transformation has been carried out for the first time, as is evident from X-ray structure analysis and X-ray powder diffractometric studies. This reaction, the dimerization of the title compound to cyclobutane derivative 1 (X=O, S), provides a good example for studying the mechanism of topochemical reactions in the crystal.

Journal Article↗
PubMed1976

[Protein crystals and tubuli bundles in yeast cells. V. Enrichment of crystal and tubuli proteins during O2 limitation and anaerobiosis].

Cells of Saccharomyces carlsbergensis contain proteins assembling to crystals and bundles of tubules (tb) in the cyto- and karyoplasm by osmotic shock with hypertonic solutions. The cellular concentration of these proteins is regulated by oxygen pressure during growth. In cells grown at optimal aeration the protein level is low and crystals and tb cannot be induced. After a short period of O2-limitation or anerobic growth conditions the protein concentration increases and induction of crystals and tb is possible.

Anaerobiosis↗
PubMed1976

[Protein crystals and tubuli bundles in yeasts cells. III. Identification of crystals as alcohol dehydrogenase (ADH)].

Inducibility of alcohol dehydrogenase (ADH) crystals in yeast cells depends on the growth phase. They accumulate during exponential growth, a process that is parallelled by accumulation of a special protein (H protein). The following pieces of evidence show that crystals, H protein, and ADH are identical: (1) The three proteins have the same amino acid composition and subunit molecular weight; (2) active H protein and ADH exhibit the same electrophoretic mobility, indicating a common molecular weight of about 158 000 D; (3) the native H protein and a crystal fraction stabilized by Zn++ and dialyzed against EDTA possess ADH activity.

Alcohol Oxidoreductases↗
PubMed1997

The crystal structure of the designed trimeric coiled coil coil-VaLd: implications for engineering crystals and supramolecular assemblies.

The three-dimensional structure of the 29-residue designed coiled coil having the amino acid sequence acetyl-E VEALEKK VAALESK VQALEKK VEALEHG-amide has been determined and refined to a crystallographic R-factor of 21.4% for all data from 10-A to 2.1-A resolution. This molecule is called coil-VaLd because it contains valine in the a heptad positions and leucine in the d heptad positions. In the trigonal crystal, three molecules, related by a crystallographic threefold axis, form a parallel three-helix bundle. The bundles are stacked head-to-tail to form a continuous coiled coil along the c-direction of the crystal. The contacts among the three helices within the coiled coil are mainly hydrophobic: four layers of valine residues alternate with four layers of leucine residues to form the core of the bundle. In contrast, mostly hydrophilic contacts mediate the interaction between trimers: here a total of two direct protein--protein hydrogen bonds are found. Based on the structure, we propose a scheme for designing crystals of peptides containing continuous two-, three-, and four-stranded coiled coils.

Amino Acid Sequence↗
PubMed1995

Isolation, crystallization, crystal structure analysis and refinement of allophycocyanin from the cyanobacterium Spirulina platensis at 2.3 A resolution.

The phycobiliprotein allophycocyanin from the cyanobacterium Spirulina platensis has been isolated and crystallized. The crystals belong to space group P6(3)22 with cell constants a = b = 101.9 A, c = 130.6 A, alpha = beta = 90 degrees, gamma = 120 degrees, with one (alpha beta) monomer in the asymmetric unit. The three-dimensional structure of the (alpha beta) monomer was solved by multiple isomorphous replacement. The crystal structure has been refined in a cyclic manner by energy-restrained crystallographic refinement and model building. The conventional crystallographic R-factor of the final model is 19.6% with data from 8.0 to 2.3 A. The molecular structure of the subunits resembles other solved phycobiliprotein structures. In comparison to C-phycocyanin and b-phycoerythrin the major differences arise from deletions and insertions of segments involved in the protein-chromophore interactions. The stereochemistry of the alpha 84 and beta 84 chiral atoms are C(2)-R, C(3)-R and C(31)-R. The configuration (C(4)-Z, C(10)-Z and C(15)-Z) and the conformation (C(5)-anti, C(9)-syn and C(14)-anti) are equal for both chromophores.

Amino Acid Sequence↗
PubMed1998

Conformational differences of an immunosuppressant peptolide in a single crystal and in a crystal complex with human cyclophilin A.

The crystal structure of (Thr2, Leu5, d-Hiv8, Leu10)-cyclosporin (cyclic peptolide SDZ 214-103) has been determined as the unbound crystal form and as a complex with human cyclophilin A. This pair of structures provides an example of a significant difference in conformation between free and bound ligand in crystals. The conformation of the unbound form is unlike that of both free and bound conformations of cyclosporin A (with the amide bond between residues 3 and 4 in the cis conformation), while the bound conformation is similar to that of CsA bound to cyclophilin. The cyclophilin-bound conformations of both ligands are similar, though this involves a significantly different waterellipsisligand hydrogen-bonding structure, which compensates for the chemical differences between the two ligands.

Cyclosporins↗
PubMed2000

The crystal structure of yeast phenylalanine tRNA at 2.0 A resolution: cleavage by Mg(2+) in 15-year old crystals.

We have re-determined the crystal structure of yeast tRNA(Phe) to 2. 0 A resolution using 15 year old crystals. The accuracy of the new structure, due both to higher resolution data and formerly unavailable refinement methods, consolidates the previous structural information, but also reveals novel details. In particular, the water structure around the tightly bound Mg(2+) is now clearly resolved, and hence provides more accurate information on the geometry of the magnesium-binding sites and the role of water molecules in coordinating the metal ions to the tRNA. We have assigned a total of ten magnesium ions and identified a partly conserved geometry for high-affinity Mg(2+ )binding. In the electron density map there is also clear density for a spermine molecule binding in the major groove of the TPsiC arm and also contacting a symmetry-related tRNA molecule. Interestingly, we have also found that two specific regions of the tRNA in the crystals are partially cleaved. The sites of hydrolysis are within the D and anticodon loops in the vicinity of Mg(2+).

Base Sequence↗
PubMed1987

Crystal-matrix relationships in experimentally induced urinary calcium oxalate monohydrate crystals, an ultrastructural study.

Calcium oxalate monohydrate crystalluria was experimentally induced in male rats by administration of ethylene glycol. The crystalluria particles were separated by filtration and studied by scanning and transmission electron microscopy. They were associated with cellular degradation products. Organic material was present both on the surfaces of crystalluria particles as well as within them and was organized in radial striations and concentric laminations. It is proposed that crystal nuclei were formed by heterogeneous nucleation. These nuclei then adsorbed organic material and aggregated. The organic material polymerized resulting in the formation of a crystal-matrix unit which then grew and incorporated more organic material during the crystal growth.

Animals↗
PubMed2004

Crystal structure of 1,10-dibromodecane and its infrared intensity in a urea clathrate and in the crystal.

The crystal structure of 1,10-dibromodecane belongs to the monoclinic system and the space group is P2(1)/c with lattice dimensions of a = 5.4574(3) A, b = 5.2814(4) A, c = 21.088(1) A and beta = 92.897(2) degrees and zeta = 2. Infrared spectra of 1,10-dibromodecane in a urea clathrate and in the crystal were observed to investigate the effect of molecular interaction on infrared intensity. The infrared intensity of the CH(2) waggings in the crystalline state is 1.5-1.9 times stronger on the relative basis than that in a urea clathrate, whereas those of CH(2) stretching, CH(2) rocking and CH(2) bending are almost the same in both states. The former enhancement is explained in terms of increase in the bond moment of the C(alpha)H(2) group on the basis of crystal structure and the electrostatic model. The relative intensity of two CH(2) asymmetric stretching changes between the two states. This is also analyzed by the use of the electrostatic model.

Alkanes↗
PubMed1995

Crystal structure of human Charcot-Leyden crystal protein, an eosinophil lysophospholipase, identifies it as a new member of the carbohydrate-binding family of galectins.

BACKGROUND: The Charcot-Leyden crystal (CLC) protein is a major autocrystallizing constituent of human eosinophils and basophils, comprising approximately 10% of the total cellular protein in these granulocytes. Identification of the distinctive hexagonal bipyramidal crystals of CLC protein in body fluids and secretions has long been considered a hallmark of eosinophil-associated allergic inflammation. Although CLC protein possesses lysophospholipase activity, its role(s) in eosinophil or basophil function or associated inflammatory responses has remained speculative. RESULTS: The crystal structure of the CLC protein has been determined at 1.8 A resolution using X-ray crystallography. The overall structural fold of CLC protein is highly similar to that of galectins -1 and -2, members of an animal lectin family formerly classified as S-type or S-Lac (soluble lactose-binding) lectins. This is the first structure of an eosinophil protein to be determined and the highest resolution structure so far determined for any member of the galectin family. CONCLUSIONS: The CLC protein structure possesses a carbohydrate-recognition domain comprising most, but not all, of the carbohydrate-binding residues that are conserved among the galectins. The protein exhibits specific (albeit weak) carbohydrate-binding activity for simple saccharides including N-acetyl-D-glucosamine and lactose. Despite CLC protein having no significant sequence or structural similarities to other lysophospholipase catalytic triad has also been identified within the CLC structure, making it a unique dual-function polypeptide. These structural findings suggest a potential intracellular and/or extracellular role(s) for the galectin-associated activities of CLC protein in eosinophil and basophil function in allergic diseases and inflammation.

Acute Disease↗
PubMed2001

Crystal structure of the 100 kDa arsenite oxidase from Alcaligenes faecalis in two crystal forms at 1.64 A and 2.03 A.

BACKGROUND: Arsenite oxidase from Alcaligenes faecalis NCIB 8687 is a molybdenum/iron protein involved in the detoxification of arsenic. It is induced by the presence of AsO(2-) (arsenite) and functions to oxidize As(III)O(2-), which binds to essential sulfhydryl groups of proteins and dithiols, to the relatively less toxic As(V)O(4)(3-) (arsenate) prior to methylation. RESULTS: Using a combination of multiple isomorphous replacement with anomalous scattering (MIRAS) and multiple-wavelength anomalous dispersion (MAD) methods, the crystal structure of arsenite oxidase was determined to 2.03 A in a P2(1) crystal form with two molecules in the asymmetric unit and to 1.64 A in a P1 crystal form with four molecules in the asymmetric unit. Arsenite oxidase consists of a large subunit of 825 residues and a small subunit of approximately 134 residues. The large subunit contains a Mo site, consisting of a Mo atom bound to two pterin cofactors, and a [3Fe-4S] cluster. The small subunit contains a Rieske-type [2Fe-2S] site. CONCLUSIONS: The large subunit of arsenite oxidase is similar to other members of the dimethylsulfoxide (DMSO) reductase family of molybdenum enzymes, particularly the dissimilatory periplasmic nitrate reductase from Desulfovibrio desulfuricans, but is unique in having no covalent bond between the polypeptide and the Mo atom. The small subunit has no counterpart among known Mo protein structures but is homologous to the Rieske [2Fe-2S] protein domain of the cytochrome bc(1) and cytochrome b(6)f complexes and to the Rieske domain of naphthalene 1,2-dioxygenase.

Alcaligenes↗
PubMed2003

Spectroscopic and optical studies on pure and doped single crystals of sulphate-mixed L-arginine phosphate monohydrate--a nonlinear optical crystal.

Single crystals of pure and transition metal ions (Cu(2+) and VO(2+))-doped L-arginine sulpho phosphate monohydrate (sulphate-mixed L-arginine phosphate monohydrate, abbreviated as LASP) have been grown by solvent evaporation of the saturated aqueous solution at room temperature and characterized by single-crystal XRD, FT-IR, UV-Vis-NIR and EPR (single-crystal rotation) spectral studies. Kurtz powder technique shows an enhanced second harmonic generation (SHG) efficiency for LASP and its doped analogues than pure LAP. The EPR studies on LASP:VO(2+) reveal that the in-plane sigma-bonding is moderately covalent and the out-of-plane pi-bonding is highly covalent, which could be attributed to the cause of enhanced powder efficiency.

Arginine↗
PubMed2003

NaCl/KCl flux single crystal growth and crystal structure of the new quaternary mixed-metal pnictide: BaCuZn3As3.

Synthesis and crystal structure of a new compound, BaCuZn(3)As(3), are reported. Single crystals of BaCuZn(3)As(3) are synthesized via NaCl/KCl flux reaction in a sealed fused silica ampule. Its elemental composition has been determined to be Ba/Cu/Zn/As = 1.03(4):1(0):2.91(6):2.98(3), suggesting BaCuZn(3)As(3) as the chemical formula. The structure of BaCuZn(3)As(3) has been determined by X-ray diffraction. It crystallizes in the orthorhombic Cmcm space group with a = 4.2277(3) A, b = 12.970(1) A, and c = 12.011(1) A at T = 90.7 K, and it exhibits a columnar structure along the a-axis. This structure is isotypic to beta-BaCu(4)S(3) but highly distorted. beta-BaCu(4)S(3) is considered to be a layered structure whereas BaCuZn(3)As(3) is a three-dimensional network.

Journal Article↗
PubMed2003

Crystals from concentrated glyme mixtures. The single-crystal structure of LiClO4.

A procedure for the preparation of high-quality single crystals from concentrated glyme mixtures is presented. Anhydrous single crystals of LiNO(3) and LiClO(4) were prepared in this manner, and the single-crystal structure of LiClO(4) (orthorhombic, Pnma, a = 8.6447(12) A, b = 6.8512(10) A, c = 4.8254(7) A, Z = 4) was determined as an example. This procedure is expected to be widely applicable for not only salts but also a wide range of other materials solvated by glymes.

Journal Article↗
PubMed2004

Synthesis, crystal structure from single-crystal and powder X-ray diffraction data, and thermal behavior of mixed potassium lanthanide squarates: thermal transformations of layered [Ln(H2O)6]K(H2C4O4)(C4O4)2 into pillared LnK(C4O4)2 (Ln = Y, La, Gd, Er).

A new series of mixed potassium and rare-earth squarates, [Ln(H(2)O)(6)]K(H(2)C(4)O(4))(C(4)O(4))(2) (Ln = Y, La, Gd, Er), has been synthesized and structurally characterized from single-crystal X-ray diffraction and spectroscopic analyses. The yttrium-based compound crystallizes with a monoclinic symmetry, space group C2/c [a = 8.3341(2) A, b = 37.7094(9) A, c = 11.7195(3) A, beta = 90.3959(9) degrees , V = 3683.1(2) A(3), Z = 8]. The structure is built from layers maintained together via hydrogen bonds. Within a layer, squarate ligands act as linkers between lanthanide and potassium cations. The thermal decomposition of the precursors has been studied by powder thermodiffractometry and thermal analyses. It is shown that crystalline intermediate phases are formed during the degradation. Among them, unprecedented mixed anhydrous squarates, LnK(C(4)O(4))(2), could be isolated. The crystal structure of the Y compound has been solved ab initio from X-ray powder diffraction data, using direct-space methods [a = 6.2010(5) A, c = 11.639(1) A, V = 447.55 A(3), Z = 2]. The structure consists of layers of edge-sharing YO(8) and KO(8) antiprisms, pillared by mu(8)-squarate groups. The end of the precursor decomposition is marked by the formation of cubic sesquioxides Ln(2)O(3), including lanthanum oxide.

Journal Article↗