Abacavir methanol 2.5-solvate

The structure of abacavir (systematic name: {(1S,4R)-4-[2-amino-6-(cyclo­propyl­amino)-9H-purin-9-yl]cyclo­pent-2-en-1-yl}methanol), C14H18N6O·2.5CH3OH, consists of hydrogen-bonded ribbons which are further held together by additional hydrogen bonds involving the hydroxyl group and two N atoms on an adjacent purine. The asymmetric unit also contains 2.5 mol­ecules of methanol solvate which were grossly disordered and were excluded using SQUEEZE subroutine in PLATON [Spek, (2009 ▶). Acta Cryst. D65, 148–155]

Klimaatverandering op de hoge zandgronden: effecten en adaptatie : betekenis van klimaatverandering voor het landelijk gebied in de provincie Gelderland : een uitwerking voor de gebiedsontwikkeling in Baakse Beek en Blauwe Bron

Doel van het project: kennis uitwisselen over klimaatverandering en functies in het landelijk gebied. Tussen wetenschap en de praktijk van gebiedsontwikkeling. Daarnaast: vanuit de gebiedsontwikkeling onderzoeksvragen formuleren voor vervolgonderzoek

High-pressure phase and transition phenomena in ammonia borane NH3BH3 from X-ray diffraction, Landau theory, and ab initio calculations

Structural evolution of a prospective hydrogen storage material, ammonia borane NH3BH3, has been studied at high pressures up to 12 GPa and at low temperatures by synchrotron powder diffraction. At 293 K and above 1.1 GPa a disordered I4mm structure reversibly transforms into a new ordered phase. Its Cmc21 structure was solved from the diffraction data, the positions of N and B atoms and the orientation of NH3 and BH3 groups were finally assigned with the help of density functional theory calculations. Group-theoretical analysis identifies a single two-component order parameter, combining ordering and atomic displacement mechanisms, which link an orientationally disordered parent phase I4mm with ordered distorted Cmc21, Pmn21 and P21 structures. We propose a generic phase diagram for NH3BH3, mapping three experimentally found and one predicted (P21) phases as a function of temperature and pressure, along with the evolution of the corresponding structural distortions. Ammonia borane belongs to the class of improper ferroelastics and we show that both temperature- and pressure-induced phase transitions can be driven to be of the second order. The role of N-H...H-B dihydrogen bonds and other intermolecular interactions in the stability of NH3BH3 polymorphs is examined.Comment: 23 pages, 7 figure

1-Benzyl-3-(1,2-diphenyl­ethen­yl)-1H-indole

In the title compound, C29H23N, the planar [maximum deviation from the least squares plane = 0.056 (1) Å] indole ring makes dihedral angles of 83.4 (4), 69.9 (1) and 59.9 (1)°, with the least-squares planes of three benzene rings. The mol­ecular packing is stabilized by weak inter­molecular C—H⋯π inter­actions

3′-(4-Chloro­benzo­yl)-4′-(4-chloro­phen­yl)-1′-methyl­spiro­[indoline-3,2′-pyrrolidin]-2-one

In the title compound, C25H20Cl2N2O2, the pyrrolidine ring adopts an envelope conformation and the best plane through the five ring atoms makes a dihedral angle of 87.03 (8)° with the indoline ring. Mol­ecules are connected by pairs of N—H⋯O hydrogen bonds into centrosymmetric dimers with an R 2 2(8) graph-set ring motif. C—H⋯O hydrogen bonds stabilize the crystal structure

A distinct epigenetic signature at targets of a leukemia protein

BACKGROUND: Human myelogenous leukemia characterized by either the non random t(8; 21)(q22; q22) or t(16; 21)(q24; q22) chromosome translocations differ for both their biological and clinical features. Some of these features could be consequent to differential epigenetic transcriptional deregulation at AML1 targets imposed by AML1-MTG8 and AML1-MTG16, the fusion proteins deriving from the two translocations. Preliminary findings showing that these fusion proteins lead to transcriptional downregulation of AML1 targets, marked by repressive chromatin changes, would support this hypothesis. Here we show that combining conventional global gene expression arrays with the power of bioinformatic genomic survey of AML1-consensus sequences is an effective strategy to identify AML1 targets whose transcription is epigenetically downregulated by the leukemia-associated AML1-MTG16 protein. RESULTS: We interrogated mouse gene expression microarrays with probes generated either from 32D cells infected with a retroviral vector carrying AML1-MTG16 and unable of granulocyte differentiation and proliferation in response to the granulocyte colony stimulating factor (G-CSF), or from 32D cells infected with the cognate empty vector. From the analysis of differential gene expression alone (using as criteria a p value < 0.01 and an absolute fold change > 3), we were unable to conclude which of the 37 genes downregulated by AML1-MTG16 were, or not, direct AML1 targets. However, when we applied a bioinformatic approach to search for AML1-consensus sequences in the 10 Kb around the gene transcription start sites, we closed on 17 potential direct AML1 targets. By focusing on the most significantly downregulated genes, we found that both the AML1-consensus and the transcription start site chromatin regions were significantly marked by aberrant repressive histone tail changes. Further, the promoter of one of these genes, containing a CpG island, was aberrantly methylated. CONCLUSION: This study shows that a leukemia-associated fusion protein can impose a distinct epigenetic repressive signature at specific sites in the genome. These findings strengthen the conclusion that leukemia-specific oncoproteins can induce non-random epigenetic changes

Ethyl 1-[2-(1H-benzotriazol-1-yl)acet­yl]-4-hy­droxy-2,6-diphenyl-1,2,5,6-tetra­hydro­pyridine-3-carboxyl­ate

In the title compound, C28H26N4O4, the tetra­hydro­pyridine ring adopts a boat conformation. The two phenyl rings form dihedral angles of 88.64 (8) and 59.28 (10)° with the best plane through the tetra­hydro­pyridine ring. The dihedral angle between the two phenyl rings is 82.55 (10)°. The benzotriazole ring system is essentially planar, with a maximum deviation of 0.009 (1) Å from the least-squares plane. The mol­ecular conformation is stabilized by an intra­molecular O—H⋯O hydrogen bond, generating an S(6) motif

1-(2-Methyl­benzo­yl)-3-m-tolyl­thio­urea

The molecule of the title compound, C16H16N2OS, is not planar; the two aromatic rings are inclined to one another by 37.59 (9)°. There are intra­molecular hydrogen bonds between the benzoyl O atom and the H atom of the thio­amide N atom, and between the thio­urea S atom and the H atom of the tolyl group. These hydrogen bonds stabilize the mol­ecule in such a way that the thio­urea group adopts a trans–cis geometry. In the crystal structure, mol­ecules are linked by N—H⋯S inter­molecular hydrogen bonds, forming centrosymmetric dimers

Bis(μ-dimesitylborinato-κ2 O:O)bis­[(2-methyl­pyridine-κN)lithium]

The title compound, [Li2(C18H22BO)2(C6H7N)2], is a lithium dimesitylboroxide dimer in which the lithium cation is also coordinated by one mol­ecule of 2-methyl­pyridine. At the core of the structure is an Li2O2 four-membered ring. The structure is centrosymmetric with an inversion centre midway between two Li atoms. Inter­molecular C—H⋯π inter­actions and π–π inter­actions between the 2-methyl­pyridine rings exist [centroid–centroid distance = 3.6312 (16) Å]

1-Formyl-r-2,c-6-bis­(4-methoxy­phen­yl)-c-3,t-3-dimethyl­piperidin-4-one

In the title compound, C22H25NO4, the piperidine ring adopts a distorted boat conformation. The two benzene rings are approximately perpendicular to each other, making a dihedral angle of 86.2 (8)°. The crystal packing is stabilized by C—H⋯O and C—H⋯π inter­actions