H. Novoa de Armas

4,4'-Dichloro-2,2'-iminodibenzoic Acid

Both rings in the title compound, C 14 H 9 Cl 2 NO 4 , are essentially planar, the r.m.s. deviation being 0.007A. The dihedral angle between the two planes is 44.8 (3)°. Dimerization occurs through hydrogen bonding of the carboxylic groups.

Tri­benzyl­phosphine oxide

The title compound, (C(6)H(5)CH(2))(3)PO, is an organic tertiary phosphine oxide. The molecule has threefold symmetry, with the P-O bond along the threefold axis. Main dimensions include P-O 1.488 (4), P-C 1.823 (3) A and O-P-C 114.7 (1) degrees. The crystals were accidentally obtained when preparing complexes of nickel(II) with dibenzylphosphine.

Ethyl Cyano(4-oxo-3-phenyl-1,3-thiazolidin-2-ylidene)acetate

There are two crystallographically independent but chemically equivalent molecules present in the asymmetric unit of the title compound, C14H12N2O3S. There are no unusual intra- or intermolecular distances or angles. The crystal packing is dominated mainly by hydrogen bonds and all rings in the molecules are essentially planar.

2-cyano-N-furfuryl-3-(2-furyl)acrylamide

In the title compound, C 13 H 10 N 2 O 3 , the two equivalent molecules in the asymmetric unit form dimers by means of an intermolecular N-H...N hydrogen bond with an N...H distance of 2.42 (2)A. There are weak intramolecular and intermolecular interactions between the C-H...N and C-H...O atoms. There are no unusual intramolecular distances or angles. The furan rings are rotated 81.1(2)° relative to each other.

The crystals of a mannose‐specific jacalin‐related lectin from Morus nigra are merohedrally twinned

MornigaM, a lectin from Morus nigra, belongs to the mannose-binding subgroup of the family of jacalin-related plant lectins. It was crystallized in the P6(5) space group, with unit-cell parameters a = b = 110.74, c = 159.28 A. The partially merohedrally twinned crystals could be detwinned and a subsequent molecular-replacement solution could be found using the coordinates of jacalin. Preliminary analysis clearly shows the tetrameric assembly of this protein. Furthermore, data from MornigaM crystals soaked in a mannose solution were collected.

(25R)-6β-Acetoxy-3β-bromo-5α-spirostan-23-one

In the title compound [systematic name: (25R)-3β-bromo-23-oxo-5α-spirostan-6-yl acetate, C 29 H 43 BrO 5 ], the C3-Br bond is oriented equatorially and (-)-antiperiplanar with respect to the C4-C5 bond. The six-membered B, C and F rings have chair conformations, as is usual in this type of compound. The five-membered D ring adopts a 14α-envelope conformation and the E ring adopts a C22β,O3α-half-chair conformation. The A/B, B/C and C/D ring junctions are trans.

Elucidation of the molecular interaction mechanism between PAI-1 and a PAI-1 inhibiting antibody fragment Fab-55F4C12

Introduction: Plasminogen activator inhibitor-1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily and is the principal inhibitor of the plasminogen activators tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) in vivo. In healthy individuals, PAI-1 is found at low levels in the plasma, but is elevated significantly in a number of diseases, including atherosclerosis, deep vein thrombosis, and non-insulin dependent diabetes mellitus. Objective: Elucidation of the molecular interaction mechanism between PAI-1 and a PAI-1 inhibiting antibody fragment Fab-55F4C12. Methods: Fab-55F4C12 was generated by papain digestion of MA-55F4C12, followed by protein A and gelfiltration purification. The purified Fab-55F4C12 was concentrated to OD = 10. Different crystallisation screens were tried, and initial crystal clusters were obtained in condition 19 of Structure Screen 1 of Molecular Dimensions. Small needles (0.2 x 0.1 x 0.1 mm) were obtained after intensive optimisation of the crystallisation condition. The crystal structure of Fab-55F4C12 was determined by X-ray crystallography at cryogenic temperature. The data set was collected at DESY (Hamburg, Germany) to a resolution of 2.7 Å. Data processing was done using MOSFLM and SCALA. The space group was assigned to be P21212 with unit-cell parameters a = 52.04 Å, b = 98.66 Å, c = 191.68 Å, with two molecules in the asymmetric unit. The data set is 99.72 % complete. Initial phases were obtained with molecular replacement. The structure was refined using Coot and Refmac5. Crystallisation of the Fab-55F4C12 / PAI-1 complex has been unsuccessful so far. Therefore, the complex is being modelled through docking of the crystal structures of the two subunits of the complex using the rigid-body docking programs DOT and ZDOC. Potential interactions between the two subunits will be deduced from the models and compared with epitope information gathered from mutagenesis studies. Conclusions: Characterization of the complex of Fab-55F4C12 with PAI-1 may provide valuable information on the molecular interactions between the Fab-fragment and PAI-1, leading to a better understanding of the mechanism of inhibition. The elucidation of the binding site of inhibitory monoclonal antibodies may contribute to the rational design of PAI-1 modulating therapeutics. m06.p03

Structure of a novel pectate lyase from Azospirillum irakense

Pectate lyases are the major pectinases that play a key role in the development of the soft-rot disease. Besides in phytopathogens, pectin depolymerization has also been reported in non-pathogenic plant associated bacteria such as the N2fixing endosymbiont Rhizobium and the N2-fixing soil bacterium Azospirillum irakense. A gene from A. irakense encoding a pectate lyase (termed PelA) was isolated by heterologous expression of the gene in Escherichia coli . Analysis of the corresponding amino acid sequence revealed no homology to other bacterial, plant and fungal pectinases leading to the classification of the enzyme in a new pectate lyase family (family 10). The A. irakense PelA has been crystallized using the hanging-drop vapor diffusion method at 277K. These crystals are hexagonal with cell dimensions of a = b = 85.55 Å, c = 230.13 Å, γ = 120°, and space group P6522 having one molecule per asymmetric unit2. Diffraction data to a resolution of 1.97 Å were collected at synchrotron facilities, as well as a three-wavelengths MAD data set on a Hg derivate crystal to a resolution of 2.6 Å. The preliminary structural results show that PelA does not have the characteristic parallel β-helix fold of the polysaccharide pectate lyase families. References 1. Bekri, M.A., Desair, J., Keijers, V., Proost, P., Searle-van Leeuwen, M., Vanderleyden, J. & VandeBroeck, A. (1999). J. Bacteriol. 181, 2440-2447. 2. Novoa de Armas, H., Rabijns A., Verboven C., Desair, J., Vande Broek, A., Vanderleyden, J., De Ranter, C. (2002). Acta Cryst. D58, 292-295.

3β-Acetoxy-5α,6β-di­hydroxybisnorcholanic acid 22\rightarrow16 lactone

In the title compound, C 24 H 36 O 6 , the ester linkage in ring A is equatorial. The six-membered rings A, B and C have chair conformations. The five-membered ring D adopts a 13β,14α-half-chair conformation and the E ring adopts an envelope conformation. The A/B, B/C and C/D ring junctions are trans, whereas the D/E junction is cis.

Sodium 2,4-dichloro-5-nitrobenzoate dihydrate

The Na+ ion is in a distorted octahedral enviroment, four vertices being occupied by water O atoms, and two by carboxylate O atoms. The structure is composed of discrete [C6H2Cl2NO2CO2] anionic units, held together by intervening Na+ ions and two water molecules.