Novel high reactive bifunctional five- and six-membered bicyclic dicarbonate - synthesis and characterisation.

Five- and six-membered bicyclic carbonates are valuable raw materials for the synthesis of environmentally friendly polymers, such as polycarbonates or non-isocyanate poly(hydroxyurethane)s. However, bicyclic diglycerol dicarbonates bearing five-membered and six-membered rings have been never reported before. In this work, for the first time, we report a simple procedure for the synthesis of this monomer from commercially available diglycerol. The product was characterised by 1H NMR, 13C NMR, FTIR spectroscopy and X-ray diffraction measurements. Next, the reactivity of the obtained bicyclic carbonate was investigated. The obtained diglycerol dicarbonate was used as a monomer for polycarbonate and non-isocyanate poly(hydroxyurethane) based on putrescine. In the homopolymerisation reaction the opening of the six-membered carbonate ring was observed, while in the polycondensation with diamine both carbonate rings open nonselectively.

Structural analysis of DNA binding by C.Csp231I, a member of a novel class of R-M controller proteins regulating gene expression.

In a wide variety of bacterial restriction-modification systems, a regulatory `controller' protein (or C-protein) is required for effective transcription of its own gene and for transcription of the endonuclease gene found on the same operon. We have recently turned our attention to a new class of controller proteins (exemplified by C.Csp231I) that have quite novel features, including a much larger DNA-binding site with an 18 bp (∼60 Å) spacer between the two palindromic DNA-binding sequences and a very different recognition sequence from the canonical GACT/AGTC. Using X-ray crystallography, the structure of the protein in complex with its 21 bp DNA-recognition sequence was solved to 1.8 Šresolution, and the molecular basis of sequence recognition in this class of proteins was elucidated. An unusual aspect of the promoter sequence is the extended spacer between the dimer binding sites, suggesting a novel interaction between the two C-protein dimers when bound to both recognition sites correctly spaced on the DNA. A U-bend model is proposed for this tetrameric complex, based on the results of gel-mobility assays, hydrodynamic analysis and the observation of key contacts at the interface between dimers in the crystal.

Hereditary spherocytosis: identification of several HS families with ankyrin and band 3 deficiency in a population of southwestern Poland.

Red blood cells of 17 patients out of seven families diagnosed with HS from the southwest of Poland were studied. In six families a deficiency of ankyrin was detected, and in one family a band 3 (anion-exchanger protein) deficiency was detected. Patients from six families with the ankyrin deficiency had a 19-51% decrease in ankyrin 2.1, while the family with the band 3 deficiency showed a 33% decrease in this protein content. All changes were statistically significant, as analysed by the Student t test (P<0.05). Analysis of haemolysis kinetics gives a reliable indication of altered osmotic properties of the spherocytic cells.

Inhibition of the Agrobacterium tumefaciens TraR quorum-sensing regulator. Interactions with the TraM anti-activator.

The Agrobacterium tumefaciens quorum-sensing transcriptional regulator TraR and its inducing ligand 3-oxo-octanoyl-l-homoserine lactone control conjugal transfer of the tumor-inducing plasmid, the primary virulence factor responsible for crown gall disease of plants. This regulatory system enables A. tumefaciens to express its conjugal transfer regulon preferentially at high population densities. TraR activity is antagonized by a second tumor-inducing plasmid-encoded protein designated TraM. TraM and TraR are thought to form an anti-activation complex that prevents TraR from recognizing its target DNA-binding sites. The formation and inhibitory function of the TraM-TraR anti-activation complex was analyzed using several different assays for protein-protein interaction, including surface plasmon resonance. The TraR-TraM complex forms readily in solution and is extremely stable (K(D) of 1-4 x 10(-9) m). Directed mutational analysis of TraM identified a number of amino acids that play important roles in the inhibition of TraR, clustering in two regions of the protein. Interestingly, several mutants were identified that proficiently bound TraR but were unable to inhibit its activity. This observation suggests a mechanistic separation between the initial assembly of the complex and conversion of TraR to an inactive form.