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The crystal structure of catalase-peroxidase from Synechococcus elongatus PCC7942 ( SeKatG) was solved by molecular replacement and refined to an Rwork of 16.8% and an Rfree of 20.6% at 2.2 Å resolution. The asymmetric unit consisted of only one subunit of the catalase-peroxidase molecule, including a protoporphyrin IX haem moiety and two sodium ions. A typical KatG covalent adduct was formed, Met248-Tyr222-Trp94, which is a key structural element for catalase activity. The crystallographic equivalent subunit was created by a twofold symmetry operation to form the functional dimer. The overall structure of the dimer was quite similar to other KatGs. One sodium ion was located close to the proximal Trp314. The location and configuration of the proximal cation site were very similar to those of typical peroxidases such as ascorbate peroxidase. These features may provide a structural basis for the behaviour of the radical localization/delocalization during the course of the enzymatic reaction. [ABSTRACT FROM AUTHOR]

Porcine pancreatic elastase (PPE) was crystallized under new sulfate-free conditions containing 0.3 M NaCl and 50 m M tris(hydroxymethyl)aminomethane-HCl at pH 7.0. The crystal structure determined at 1.5 Å resolution had a unique conformation in four regions which contained loop portions. A chloride ion was bound near the catalytic triad instead of the sulfate ion in PDB entry , a typical PPE crystal structure. However, the chloride ion did not affect the configuration of the catalytic triad. A tris(hydroxymethyl)aminomethane (Tris) molecule was bound to the S4 and S5 subsites in place of the adjacent molecule in the crystal and played a significant role in the structural change of the region. The distortion in this region may subsequently have induced conformational changes in the other three regions. The fact that Tris and these four regions make a diagonal line in the ac plane may have affected the crystal-packing contraction along the a and c axes in the crystal compared with the typical crystal. [ABSTRACT FROM AUTHOR]

The NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of Synechococcus PCC 7942 was crystallized in two different forms by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant. Form I crystals were hexagonal, space group P65 or P61, with unit-cell parameters a = b = 91.1, c 428.6 Å, γ = 120°. Form II crystals were monoclinic, space group C2, with unit-cell parameters a = 152.3, b = 80.9, c= 213.6 Å, β = 103.1°. Native data were collected from a frozen crystal of form I to a resolution of 2.8 Å using synchrotron radiation at SPring-8, whereas form II crystals were easily damaged by radiation at room temperature and increased mosaicity in cryoprotectant solutions. A molecular-replacement solution of the form I crystal was obtained in space group P65 using the program AMoRe and the structure of the NAD-dependent GAPDH from Bacillus stearothermophilus. [ABSTRACT FROM AUTHOR]

Cephalosporin C acylase from Pseudomonas sp. strain N176, a heterodimer of 25 and 58 kDa, has been crystallized using polyethylene glycol 6000 as precipitant. The crystals are ortho-rhombic and have unit-cell parameters a = 141.41, b = 192.10, c = 80.75 Å. They belong to space group P212121 and diffract to at least 2.7 Å resolution. Calculations indicate that there are two heterodimers in the asymmetric unit. The structure is being solved by molecular replacement using penicillin G acylase from Escherichia coli as a search model and by multiple isomorphous replacement. [ABSTRACT FROM AUTHOR]

Abstract: We determined the 2.35-Å crystal structure of a human CK2 catalytic subunit (referred to as CK2α complexed with the ATP-competitive, potent CK2 inhibitor ellagic acid. The inhibitor binds to CK2α with a novel binding mode, including water-mediated hydrogen bonds. This structural information may support discovery of potent CK2 inhibitors. [Copyright &y& Elsevier]

Abstract: A new ternary uranium-based intermetallic compound U3Ni5Al19 has been synthesized. It crystallizes in the unique flat orthorhombic structure. Uranium atoms occupy two crystallographic 4c and 8f sites of quite similar local chemical environments. The temperature dependence of the magnetic susceptibility demonstrates peculiar magnetic anisotropy; along the b- and c-axis obeys the Curie–Weiss law above 23K, while along a-axis is small and temperature independent. At 23K, only shows a sharp cusp corresponding to an antiferromagnetic ordering, while remains paramagnetic down to 2K. From the crystallographical structure we suggest that only uranium atoms at the 8c site order antiferromagnetically at , while those occupying the 4c site do not order down to 50mK. [Copyright &y& Elsevier]