H.L. De Bondt

The structure of mouse tumour-necrosis factor at 1.4 A resolution: towards modulation of its selectivity and trimerization.

The 1.4 A resolution structure of recombinant mouse tumour-necrosis factor alpha (mTNF) at 100 K has been determined. The crystals are triclinic, space group P1, with unit-cell parameters a = 48.06, b = 48.18, c = 51.01 A, alpha = 114.8, beta = 103.6, gamma = 91.1 degrees. The structure was refined to a final crystallographic R value of 19.7% (Rfree = 23.3%), including 3477 protein atoms, one 2-propanol molecule, one Tris molecule and 240 water molecules. Throughout the crystal lattice, the trimers are differently packed compared with human TNF, which was crystallized in the tetragonal space group P41212 and refined to 2.6 A resolution. The structures of mTNF and human TNF are very similar, diverging mainly in regions that are either flexible and/or involved in crystal packing. Some loops in mTNF which contain residues important for receptor binding are better resolved than in human TNF, such as the surface-exposed loops 30-34 and 144-147, which are also important for receptor specificity. Compared with human TNFs, the channel formed by the three monomers in mTNF is narrower. One 2-propanol molecule trapped in the trimeric channel could be a lead compound for the design of TNF inhibitors.

Structure of 4(5)-nitroimidazole at 100 K

4(5)-Nitroimidazole, C 3 H 3 N 3 O 2 , M r =113.08, monoclinic, P2 1 /n, a=6.9559 (4), b=9.9130 (6), c=7.3045 (4) A, β=119.41 (4) o , V=438.8 (4) A 3 , Z=4, D m (293 K)=1.64, D x =1.7117 Mg m -3 , λ(Mo Kα)=0.71069 A, μ=0.1367 mm -1 , F(000)=232, T=100 K. Final R=0.024 for 633 unique observed [F≥4σ(F)] reflections. The molecules are planar and are stacked in planes almost parallel to the bc plane. These molecular layers are built up by three hydrogen bonds. 4-5-tautomerism is discussed

Plasminogen activator inhibitor 1 (PAI-1) in its active conformation: crystallization and preliminary X-ray diffraction data

Because of its intrinsic lability, wild-type plasminogen activator inhibitor 1 (PAI-1) cannot be crystallized in its active conformation. Therefore, a stable variant of PAI-1 was used to retain the active conformation during crystallization. Four different crystallization conditions were evaluated in detail and two major types of crystals were detected. Whereas solutions consisting of either (i) cacodylate and sodium acetate, (ii) lithium sulfate and polyethylene glycol 4K, or (iii) imidazole, sodium chloride and sodium potassium phosphate buffer revealed thin platelet crystals, a solution (iv) containing ammonium acetate, citrate and polyethylene glycol 4K appeared to enhance the formation of clustered brush-like crystals. Crystals grown under condition (iii) were found to be suitable for X-ray data collection and consequent structural investigation. Data collection was 79.8% complete with a maximum resolution of 2.92 A. Importantly, PAI-1 retained its functional properties under all conditions.

trans-Dichlorobis(metronidazole)palladium(II), [PdCl2(C6H9N3O3)2]

The title complex, dichlorobis(2-methyl-5-nitroimidazole-1-ethanol-N 3 )palladium(II), is trans square planar. The imidazole ring forms an angle of 88.8 (3) o with the square plane around the Pd atom, and an angle of 3.9 (4) o with the nitro group

Crystallization and preliminary X-ray studies of mouse tumor necrosis factor.

Well diffracting crystals of recombinant mouse tumor necrosis factor (mTNF) have been obtained. The sitting-drop vapor-diffusion method was used to grow crystals suitable for X-ray studies from solutions containing methoxypolyethylene glycol 2000 and isopropanol as precipitants. The crystals belong to the space group P1 with unit-cell dimensions a = 49.40, b = 48.24, c = 51.13 A, alpha = 115.06, beta = 103.32, gamma = 91.27 degrees and one trimer in the asymmetric unit. Crystals are stable to X-rays and diffract beyond 2.0 A. Cooling the crystal during data collection is necessary since crystals dissolve at room temperature.

A fully functional deletion staphylokinase derivative crystallizes in two non-isomorphous monoclinic modifications

Two non-isomorphous monoclinic types of diffraction-quality crystals of Delta10Sak, a fully functional staphylokinase derivative lacking the first ten amino acids, have been grown by the hanging-drop vapour-diffusion technique. Type I crystals grow from a solution containing Zn(OAc)2, Tris buffer pH 7.5 and PEG 8000, while type II crystals can be obtained from a solution containing MgCl2, Tris buffer pH 8.5 and PEG 4000. Both crystal types were suitable for data collection (to 2.4 and 2.6 A resolution, respectively) and further structural investigation.

Structure of 5-benzylamino-1-methyl-4-nitroimidazole

C 11 H 12 N 4 O 2 , M r =232.24, orthorhombic, Pbca, a=6.962 (4), b=13.754 (7), c=22.974 (12) A, V2200 (2) A ○. , Z8, D m =1.40, D x =1.402 Mg m -3 , graphite-monochromated Cu Kα radiation, λ=1.54178 A, μ=0.794 mm -1 , F(000)=976, T=293 K, final R=0.035 for 1143 unique observed [F≥4σ(F)] reflections. The phenyl ring and the nitro group make angles of 50.8 and 3.6 o , respectively, to the imidazole ring. An intermolecular hydrogen bond exists parallel to the b axis