Proteome analysis demonstrates complex replicon and luteolin interactions in pSyma-cured derivatives of Sinorhizobium meliloti strain 2011

Sinorhizobium meliloti was studied by proteomic analysis to investigate the contribution made by plasmid-encoded functions on the intracellular regulation of this bacterium. Protein profiles of strain 2011 were compared with those from its mutant strains which were either cured of their pRme2011a (also called pSyma) plasmid (strain 818), or contained an extensive deletion of this plasmid (strain SmA146). Plasmid pSyma contains the nodulation and nitrogen fixation genes and is 1.4 Mbp with an estimated coding potential of 1,400 proteins. However, under the growth conditions used we could detect 60 differences between the parent strain and its pSyma-cured derivative, strain 818. While the majority of these differences were due to regulatory changes, such as up- and downregulation, some proteins were totally missing in some strains. These 60 proteins were classified into 21 subgroups, A to U, based on their measured protein levels when the cells were grown in the presence or absence of luteolin. Comparisons were made between the different strains to assess the possible interactions of the different proteins of the subgroups and plasmid pSyma. These results suggest that pSyma has a role in the regulation of the expression of genes from the other replicons (3.5 Mbp chromosome and the 1.7 Mbp pSymB plasmid) present in the S. meliloti cells. Proteome analysis provides a sensitive tool to examine the functional organisation of the S. meliloti genome and the intracellular gene interactions between replicons and will provide a powerful analytical tool to complement the genome sequencing of strain 1021.     

Enantioselective organocatalytic Michael addition of malonate esters to nitro olefins using bifunctional cinchonine derivatives

A family of 9-amino(9-deoxy) epicinchonine derivatives, possessing a range of mono- and bidentate hydrogen bond donor groups at the 9-position, were synthesised and evaluated for asymmetric organocatalytic activity in the dimethyl malonate Michael addition to beta-nitrostyrene; thiourea derivative was identified as the most effective bifunctional organic catalyst and found to induce high enantioselectivity in the malonate ester Michael addition reaction to a range of nitro olefins.     

Nonlinear momentum relaxation of an impurity in a harmonic chain

A microscopic derivation of the generalized Langevin equation for arbitrary powers of the momentum of an impurity in a harmonic chain is presented. As a direct consequence of the Gaussian character of the conditional momentum distribution function, nonlinear momentum coupling effects are absent for this system and the Langevin equation takes on a particularly simple form. The kernels which characterize the decay of higher powers of the impurity momentum depend on the ratio of the masses of the impurity and bath particles, in contrast to the situation for the momentum Langevin equation for this system. The simplicity of the harmonic chain dynamics is exploited in order to investigate several features of the relaxation, such as the factorization approximation for time-dependent correlation functions and the decay of the kinetic energy autocorrelation function.     

Studies on the application of salts of complex cations to the microscopic detection of anions

Summary Crystalline reaction products were obtained when 1,6-carbonatotetramminocobaltic nitrate reacts with bifluoride and bromate ions.

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Zusammenfassung Bei der Reaktion von 1,6-Carbonatotetramminokobaltinitrat mit Bifluorid-und Bromat-Ion wurden kristalline Reaktionsprodukte erhalten.

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Résumé On a obtenu des produits de réaction cristallisés, en faisant réagir le nitrate de 1,6-carbonatotetramminocobalte avec des ions de bifluorure et de bromate.

     

A Model Electron Transfer Reaction in Confined Aqueous Solution

Liquid water confined within nanometer-sized channels exhibits a strongly reduced local dielectric constant perpendicular to the wall, especially at the interface, and this has been suggested to induce faster electron transfer kinetics at the interface than in the bulk. We study a model electron transfer reaction in aqueous solution confined between graphene sheets with classical molecular dynamics. We show that the solvent reorganization energy is reduced at the interface compared to the bulk, which explains the larger rate constant. However, this facilitated solvent reorganization is due to the partial desolvation by the graphene sheet of the ions involved in the electron transfer and not to a local dielectric constant reduction effect.     

Anion-pi interaction augments halide binding in solution

1H NMR spectroscopic data and complementary theoretical predictions suggest that a designed receptor exhibits the anion-pi interaction in solution.