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First X-ray Structure (first + x-ray_structure)

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Chemistry100%

Selected Abstracts

Synthesis of Dihalo-Substituted Analogues of Tröger's Base from ortho - and meta -Substituted Anilines

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2003
Anna Hansson
Abstract For the first time, ortho - and meta -halo-substituted anilines were successfully condensed with formaldehyde to dihalo-substituted analogues of Tröger's base. By using paraformaldehyde and TFA, yields of 2,85% of these potential supramolecular building blocks were obtained. Even the inconceivable achievement of condensing anilines unsubstituted in para -position to analogues of Tröger's base was successful. Adding our present results to our previous, makes it now possible to synthesize analogues of Tröger's base halo-substituted in almost any desired position in each of its two aromatic rings. In addition the first X-ray structure of a dihalo-substituted analogue of Tröger's base, 3,9-dibromo-4,10-dimethyl-6H,12H -5,11-methanodibenzo[b,f][1,5]diazocine (17), is presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Structure of the single-stranded DNA-binding protein from Streptomyces coelicolor

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2009
Zoran, tefani
The crystal structure of the single-stranded DNA-binding protein (SSB) from Streptomyces coelicolor, a filamentous soil bacterium with a complex life cycle and a linear chromosome, has been solved and refined at 2.1,Å resolution. The three-dimensional structure shows a common conserved central OB-fold that is found in all structurally determined SSB proteins. However, it shows variations in quaternary structure that have previously only been found in mycobacterial SSBs. The strand involved in the clamp mechanism characteristic of this type of quaternary structure leads to higher stability of the homotetramer. To the best of our knowledge, this is the first X-ray structure of an SSB protein from a member of the genus Streptomyces and it was predicted to be the most stable of the structurally characterized bacterial or human mitochondrial SSBs. [source]

How the CO in myoglobin acquired its bend: lessons in interpretation of crystallographic data

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2001
Boguslaw Stec
Contrary to the expectation of chemists, the first X-ray structures of carbon monoxide bound to myoglobin (Mb) showed a highly distorted Fe,C,O bond system. These results appeared to support the idea of a largely steric mechanism for discrimination by the protein against CO binding, a lethal act for the protein in terms of its physiological function. The most recent independently determined high-resolution structures of Mb,CO have allowed the 25,year old controversy concerning the mode of CO binding to be resolved. The CO is now seen to bind in a roughly linear fashion without substantial bending, consistent with chemical expectations and spectroscopic measurements. Access to deposited diffraction data prompted a reevaluation of the sources of the original misinterpretation. A series of careful refinements of models against the data at high (1.1,Å) and modest resolutions (1.5,Å) have been performed in anisotropic versus isotropic modes. The results suggest that the original artifact was a result of lower quality crystals combined with anisotropic motion and limited resolution of the diffraction data sets. This retrospective analysis should serve as a caution for all researchers using structural tools to draw far-reaching biochemical conclusions. [source]

Crystal Structures of the PBP2 Glycosyltransferase Domain: New Opportunities for Antibacterial Drug Design

CHEMMEDCHEM, Issue 10 2007
Johannes Zuegg Dr.
The recent publication by Strynadka and colleagues, describing the first X-ray structures of a soluble truncated version of PBP2 containing both glycosyltransferase and transpeptidase domains facilitates more common and feasible approaches for the rational design and in turn clinically useful GT-inhibitors for the treatment of infections caused by highly resistant bacterial organisms. [source]