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The article discusses a study on the high-resolution structure of exo-arabinanase from Penicillium chrysogenum. The authors state that crystallization conditions giving high-quality crystals of Abnx were established successfully by what they call the novel technique referred to as COLAS. They also say that the structures presented in the article could reveal that Abnx has different mechanisms to funnel substrates to the active site and/or to stabilize the transition state compared with the arabinan-degrading enzyme Arb93A.

Abstract: Adenosine deaminase (ADA) perpetuates chronic inflammation by degrading extracellular adenosine which is toxic for lymphocytes. ADA has two distinct conformations: open form and closed form. From the crystal structures with various ligands, the non-nucleoside type inhibitors bind to the active site occupying the critical water-binding-position and sustain the open form of apo-ADA. In contrast, substrate mimics do not occupy the critical position, and induce the large conformational change to the closed form. However, it is difficult to predict the binding of (+)-erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), as it possesses characteristic parts of both the substrate and the non-nucleoside inhibitors. The crystal structure shows that EHNA binds to the open form through a novel recognition of the adenine base accompanying conformational change from the closed form of the PR–ADA complex in crystalline state. [Copyright &y& Elsevier]

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]

Fructose-1,6-/sedoheptulose-1,7-bisphosphatase of Synechococcus PCC 7942, overexpressed from Escherichia coli, has been purified and crystallized by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant. The crystals were monoclinic, with unit-cell parameters a = 80.1, b = 84.2, c = 104.3 Å, β = 101.7°. They belonged to space group P21 and diffracted to at least 2.2 Å resolution. The calculated VM value, based on a tetramer in the asymmetric unit, was 2.2 ų Da-1. [ABSTRACT FROM AUTHOR]

Endopolygalacturonase SE1 from Trichosporon penicillatum has been crystallized by the hanging-drop method of vapour diffusion using ammonium sulfate as a precipitant. The crystals belong to the hexagonal space group P61 or P65, with unit-cell parameters a = b = 135.0, c = 70.7 Å, γ = 120°. The calculated VM based on one molecule per asymmetric unit is 3.09 ų Da-1. A native data set from a crystal has been collected to 2.0 Å resolution on a Cu Kα rotating-anode X-ray source. [ABSTRACT FROM AUTHOR]

Abstract: Bimolecular fluorescence complementation (BiFC) assay has been used widely to visualize protein–protein interactions in cells. However, there is a problem that fluorescent protein fragments have an ability to associate with each other independent of an interaction between proteins fused to the fragments. To facilitate the BiFC assay, we have attempted to determine the structure and characteristics of reassembled fluorescent protein, Venus. The anion-exchange chromatography showed an oligomer and a monomer of reassembled Venus. Our results suggested that the oligomer was formed by β-strands swapping without any serious steric clashes and was converted to the monomer. Crystal structure of reassembled Venus had an 11-stranded β-barrel fold, typical of GFP-derived fluorescent proteins. Based on the structural features, we have mutated to β-strand 7 and measured T m values. The results have revealed that the mutation influences the thermal stability of reassembled fluorescent complex. [Copyright &y& Elsevier]

Abstract: MKK4 activates both JNKs and p38s. We determined the crystal structures of human non-phosphorylated MKK4 kinase domain (npMKK4) complexed with AMP–PNP (npMKK4/AMP) and a ternary complex of npMKK4, AMP–PNP and p38α peptide (npMKK4/AMP/p38). These crystal structures revealed that the p38α peptide-bound npMKK4 at the allosteric site rather than at the putative substrate binding site and induced an auto-inhibition state. While the activation loop of the npMKK4/AMP complex was disordered, in the npMKK4/AMP/p38 complex it configured a long α-helix, which prevented substrate access to the active site and αC-helix movement to the active configuration of MKK4. [ABSTRACT FROM AUTHOR]

Two donor molecules newly synthesized, dimethylthio- and ethylenedithio-tetrathiafulvalenothioquinone-1,3diselenolemethides (1 and 2), were used to prepare their charge-transfer (CT) salts with a magnetic FeBr[sub 4, sup -] counteranion. For 1, a low electrical conducting 1:1 salt (1·FeBr[sub 4]) was obtained, in which molecules of 1 are tightly dimerized in a one-dimensional (1D) stacking column. On the other hand, 2 gave a 2:1 salt (2[sub 2]·FeBr[sub 4]) as two different kinds of plate crystals (I and II). Both I and II possess similar stacking structures of molecules of 2 in each 1D column with a half-cut pipelike structure along the c axis. However, for I, the stacking columns are aligned in the same direction along the a and b axes, while for II they are in the same direction along the a axis, but in the reverse direction along the b axis, resulting in the difference in the relative arrangement of molecules of 2 and FeBr[sub 4, sup -] ions between the two crystals. The room-temperature electrical conductivities of the single crystals of I and II were 13.6 and 12.7 S cm[sup -1], respectively. The electrical conducting behavior in I was metallic above 170 K but changed to be semiconducting with a very small activation energy of 7.0 meV in the temperature range 4-170 K. In contrast, II showed the semiconducting behavior in the whole temperature range 77-285 K. The corresponding nonmagnetic GaBr,- salts with almost the same crystal structure as I and II showed definitively different electrical conducting properties in the metal to semiconductor transition temperature in I as well as in the magnitude of activation energy in the semiconducting region of I and II. The interaction between the d spins of FeBr[sub 4, sup -] ions was weak and antiferromagnetic in both I and II, but the magnitude of the spin interaction was unexpectedly larger compared with that in the FeBr[sub 4, sup -] salt of the corresponding sulfur derivative of 2 with closer contact between the neighboring FeBr[sub 4, sup -] ions. These electrical conducting and magnetic results suggest a significant interaction between the conducting π electrons and the d spins of FeBr[sub 4, sup -] ions located near the columns or layers. [ABSTRACT FROM AUTHOR]