Towards structural studies of the old yellow enzyme homologue SYE4 from Shewanella oneidensis and its complexes at atomic resolution

Shewanella oneidensis is an environmentally versatile Gram-negative gamma-proteo-bacterium that is endowed with an unusually large proteome of redox proteins. Of the four old yellow enzyme (OYE) homologues found in S. oneidensis, SYE4 is the homologue most implicated in resistance to oxidative stress. SYE4 was recombinantly expressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals belonged to the orthorhombic space group P2(1)2(1)2(1) and were moderately pseudo-merohedrally twinned, emulating a P422 metric symmetry. The native crystals of SYE4 were of exceptional diffraction quality and provided complete data to 1.10 angstrom resolution using synchrotron radiation, while crystals of the reduced enzyme and of the enzyme in complex with a wide range of ligands typically led to high-quality complete data sets to 1.30-1.60 angstrom resolution, thus providing a rare opportunity to dissect the structure-function relationships of a good-sized enzyme (40 kDa) at true atomic resolution. Here, the attainment of a number of experimental milestones in the crystallographic studies of SYE4 and its complexes are reported, including isolation of the elusive hydride-Meisenheimer complex

Sr5(VIVOF5)3F(H2O)3 refined from a non-merohedrally twinned crystal

The title compound, pentastrontium tris[pentafluoridooxidovanadate(IV)] fluoride trihydrate, was obtained under hydrothermal conditions. Its crystal structure has been refined from intensity data of a non-merohedrally twinned crystal. Two domains in almost equal proportions are related by a −180° rotation along the reciprocal [101]* vector. The structure may be considered as a derivative of the fluorite structure type, adopted here by SrF2. In the title compound, fluorite-like large rods are recognized, built up from a group of 16 Sr atoms of which 6 are substituted by V atoms, leading to [Sr10V6]∞ units. These rods extend infinitely along the b axis and are interconnected by the three water molecules. Each of the water molecules is shared by two different Sr atoms belonging to two different rods. The rods are also interconnected by an `independent' F atom in a distorted triangular [FSr3] coordination and by hydrogen-bonding interactions via donor water molecules. The acceptors are either F atoms or the O atoms of the vanadyl ion, VO2+, that is part of the [VOF5] isolated octahedron

Preparation and NMR spectra of four isomeric diformyl[2.2]paracyclophanes (cyclophanes 66)

Four isomeric dialdehydes 4, readily available from cycloaddition of propiolic aldehyde (2) to 1,2,4,5-hexatetraene (1), were separated by chromatography and recrystallization, and were characterized by their spectroscopic data. The individual isomers can now be easily identified from their 1H NMR spectra even if only one of them is present

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

With the goal of eventually synthesizing [5]radialene (3), the still missing member of the parent radialene hydrocarbons, we have prepared the pentaacetates 21 and 31, the pentabromide 29 and the hexabromide 32. In principle these should be convertible by elimination reactions to the desired target molecule

Synthesis and structure of a New [6.6]metacyclophane with enediyne bridges

Synthesis and structure of a novel [6.6]metacyclophane with enediyne bridges is reported

Syntheses and structures of isomeric [6.6]- and [8.8]Cyclophanes with 1,4-dioxabut-2-yne and 1,6-dioxahexa-2,4-diyne bridges

All three isomers (ortho, meta, and para) of [8.8]cyclophane bearing 1,6-dioxahexa-2,4-diyne bridges have been synthesized and structually characterized by single-crystal X-ray crystallography to determine the conformation of the cyclophanes and their cavity dimensions. The three isomeric [6.6]cyclophanes bearing 1,4-dioxabut-2-yne bridges have also been synthesized from but-2-yne-1,4-diol ditosylate and the isomeric dihydroxybenzenes. The [6.6]orthocyclophane has been structurally characterized by single-crystal X-ray crystallography. The energy-minimized structures from the semiempirical AM1 calculations of these cyclophanes compare very well with the structures obtained by X-ray crystallography

Synthesis, Structure, and First Reactions of a New Class of Thiacyclophanes

In our effort to prepare [m.n]cyclophanes carrying functional groups in their molecular bridges, the thiacyclophanes 14, 19, 20, and 21 have been prepared by simple routes from the pseudo-gem dibromide 10a and the corresponding bis-thiol 10b. The triply-bridged bis-thiacyclophanes 14, and 19-21 were characterized by their spectroscopic data as well as by X-ray structural analyses. The meta-isomer 20 was oxidized to the bis-sulfone 23, which, on flash vacuum pyrolysis (FVP) yielded a product mixture presumably containing the hydrocarbon 26 with a cleaved molecular bridge. Subjecting 23 to Ramberg-B채cklund conditions (CCl4, NaOH, phase transfer catalysis) provided the chloride 24 in poor yield (9%), a [2.2]paracyclophane in which the new molecular bridge is fully conjugated.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author