ABSTRACT
The DNA decamers d(CCGGATCCGG) and d(CCGGCGCCGG) have been crystallized for X-ray analysis in order to investigate the effects of changing the two central base pairs of the DNA fragment d(CCGGGACCGG). Previous studies have already demonstrated that the structure of the former DNA fragment contains a DNA Holliday junction. Crystals were obtained at 293 K by the hanging-drop vapour-diffusion technique using the Nucleic Acid Mini Screen. Over a period of two weeks, hexagonal plates appeared. For the DNA fragment d(CCGGATCCGG), the crystals belong to space group P3(1), with unit-cell parameters a = b = 33.54, c = 46.39 A, alpha = beta = 90, gamma = 120 degrees, and diffract to 2.2 A. In the case of the DNA fragment d(CCGGCGCCGG) the crystals belong to the space group C2, with unit-cell parameters a = 65.35, b = 24.07, c = 37.34 A, beta = 109.97 degrees, and diffract to 2.0 A.
Subject(s)
DNA/chemistry , Crystallization , Crystallography, X-Ray , Models, Molecular , Nucleic Acid Conformation , RNA/chemistryABSTRACT
Crystals of the indoloquinoline alkaloid cryptolepine complexed with the DNA fragment d(CCTAGG)(2) have been grown by the hanging-drop technique at 293 K using ammonium sulfate as the precipitating agent. Over a period of three weeks, yellow tapering bullet-shaped crystals grew to maximum dimensions of 0.2 x 0.1 x 0.1 mm. The crystals belong to space group P6(4), with unit-cell parameters a = b = 29.960, c = 39.64 A, alpha = beta = 90, gamma = 120 degrees, and diffract to 1.4 A.
Subject(s)
Alkaloids/chemistry , Alkaloids/metabolism , Antimalarials/chemistry , DNA/chemistry , DNA/metabolism , Indoles/chemistry , Indoles/metabolism , Quinolines/chemistry , Quinolines/metabolism , Antimalarials/metabolism , Crystallization , Crystallography, X-Ray , Indole Alkaloids , Models, Molecular , Nucleic Acid ConformationABSTRACT
The structure of the crown ether 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol, C(24)H(30)O(6).H(2)O (1), code name P326, the parent compound for a series of derivatives, has been determined by both X-ray diffraction at room temperature and neutron diffraction at very low temperature. The unit cells are very similar at both temperatures and in both cases the crystals exhibit P2(1) symmetry with Z = 4 (two molecules, A and B, respectively, per asymmetric unit) and pseudosymmetry P2(1)/c. The higher symmetry is broken mainly by the two independent water molecules in the unit cell, some reflections which would be absent in P2(1)/c having strong intensities in both the X-ray and neutron data. In both molecules A and B hydrogen bonds involving the water molecule stabilize the macrocyclic ring structure, one involving the macrocyclic O(9) as a donor. Close contacts between the water and macrocyclic O atoms in each molecule also suggest the presence of two bifurcated hydrogen bonds, involving water HW2 to both O(16) and O(18), and water HW1 to both O(18) and O(20), respectively, with considerable variation in the geometry being present. Both molecules A and B exhibit very close pseudosymmetry across a plane perpendicular to the molecular plane and through atoms C(9) and O(18), and in addition are predominantly planar structures. The X-ray analysis failed to reveal one H atom per water molecule, each being subsequently included after location and refinement in the neutron analysis.
ABSTRACT
Crystals of Helix pomatia agglutinin (HPA) have been grown by the hanging-drop technique using polyethylene glycol as the precipitant at 293 K. Over a period of one to two weeks the crystals grew to maximum dimensions of 0.10 x 0.05 x 0.02 mm. The crystals belong to space group P6(3)22, with unit-cell dimensions a = b = 63.3, c = 105. 2 A and Z = 12 identical monomers of M(r) = 13 kDa, aggregating into two 78 kDa hexameric protein molecules per unit cell, each with symmetry 32 (D(3)). The diffraction pattern extends to 3.6 A at 293 K.
Subject(s)
Lectins/chemistry , Animals , Crystallization , Crystallography , Crystallography, X-Ray , Dimerization , Helix, Snails , Models, Molecular , Polyethylene Glycols/pharmacology , Protein ConformationABSTRACT
Crystals of Pleurotus ostreatus (oyster mushroom) lectin have been grown by the hanging-drop technique using ammonium sulfate as the precipitant at 293 K. Over a period of between two and three weeks, crystals of hexagonal bipyramidal morphology grew to maximum dimensions of 0.2 x 0.2 x 0.5 mm. The crystals belong to space group P6(1)22 or P6(5)22, with unit-cell parameters a = b = 155.9, c = 149. 8 A, V = 3153078 A(3), Z = 12 (assuming 50% solvent), and diffract to 4.1 A at 293 K.
Subject(s)
Fungal Proteins/chemistry , Lectins/chemistry , Pleurotus/chemistry , Ammonium Sulfate , Chemical Precipitation , Crystallization , Lectins/isolation & purification , X-Ray DiffractionABSTRACT
The X-ray structure of the inhibitor complex of bovine ribonuclease A with cytidylic acid (2'-CMP) has been determined at 1.6 A resolution and refined by restrained least squares to R = 0.17 for 11 945 reflections. Binding of the inhibitor molecule to the protein is confirmed to be in the productive mode associated with enzyme activity. A study of conserved solvent sites amongst high-resolution structures in the same crystal form reveals a stabilizing water cluster between the N and C termini.
ABSTRACT
C14H18O3, Mr = 234.29, monoclinic, P2(1)/a, a = 14.550 (8), b = 6.133 (4), c = 15.703 (7) A, beta = 116.1 (4) degree, V = 1254.4 (5) A3, Z = 4, Dm = 1.24 (4), Dx = 1.239 g cm-3, lambda (Cu K alpha) = 1.54184 A, mu = 6.15 cm-1, F(000) = 504, room temperature, R = 0.065 for 2426 observed reflections. The five-membered ring A has an envelope conformation, the apical atom C(7)* being out of the plane. The conformation of the side chain attached to C(1)* is almost fully extended. The molecules are packed in a head-to-tail fashion as hydrogen-bonded dimers: O(3)...O(4)* [1-x, y, 1-z] = 3.124 (8), HO(3)...O(4)* = 2.19 (9) A, O(3)-HO(8)...O(4)* V 160.2 (6) degree.
Subject(s)
Anticonvulsants , Dioxolanes , Dioxoles , Models, Molecular , Molecular Structure , X-Ray DiffractionABSTRACT
C8H8N2O3S, Mr = 212.54, monoclinic, P2(1)/a, a = 7.347 (9), b = 13.237 (4), c = 10.128 (8) A, beta = 108.916 (6) degree, V = 931.9 (1) A3, Z = 4, Dm = 1.52 (4), Dx = 1.514 g cm-3, lambda (Cu K alpha) = 1.54184 A, mu = 28.35 cm-1, F(000) = 440, room temperature, R = 0.040 for 1864 observed reflections. The sulfonamide N forms intermolecular hydrogen bonds with the benzisoxazole ring N and also with the O on the sulfonamide group. Centrosymmetrically related benzisoxazole ring pairs are pi bonded with a high degree of overlap.
