We report that l-threonine may substitute for l-serine in the β-substitution reaction of an engineered subunit of tryptophan synthase from Pyrococcus furiosus, yielding (2S,3S)-β-methyltryptophan (β-MeTrp) in a single step. The trace activity of the wild-type β-subunit on this substrate was enhanced more than 1000-fold by directed evolution. Structural and spectroscopic data indicate that this ...

Background: Enterococci faecalis are predominating species of Enterococci causing nosocomial infections. Acquisition of resistance to antibacterial agents, and ability to transfer the resistant genes made them clinically important. This study was performed to determine the frequency of isolation of different species of Enterococci, and the antibacterial resistance pattern of the isolated specie...

Given a 3-colourable graph G and two proper vertex 3-colourings α and β of G, consider the following question : is it possible to transform α into β by recolouring vertices of G one at a time, making sure that all intermediate colourings are proper 3-colourings? We prove that this question is answerable in polynomial time. We do so by characterising the instances G,α, β where the transformation...

Although nitrogen (N) availability is a major determinant of ecosystem properties, little is known about the ecological importance of plants' preference for ammonium versus nitrate (β) for ecosystem functioning and the structure of communities. We modeled this preference for two contrasting ecosystems and showed that β significantly affects ecosystem properties such as biomass, productivity, an...

BACKGROUND & OBJECTIVES Acinetobacter baumannii is a Gram-negative, cocco-bacillus aerobic pathogen responsible for nosocomial infections in hospitals. In the recent past A. baumannii had developed resistance against β-lactams, even against carbapenems. Penicillin-binding proteins (PBPs) are crucial for the cell wall biosynthesis during cell proliferation and these are the target for β-lactams....

Conversion of native cellular prion protein (PrPc) from an α-helical structure to a toxic and infectious β-sheet structure (PrPSc) is a critical step in the development of prion disease. There are some indications that the formation of PrPSc is preceded by a β-sheet rich PrP (PrPβ) form which is non-infectious, but is an intermediate in the formation of infectious PrPSc. Furthermore the presenc...

The synthesis and characterization of "2 + 1" complexes of the [M(CO)(3)](+) (M = Re, (99m)Tc) core with the β-diketones acetylacetone (complexes 2, 8) and curcumin (complexes 5, 10 and 6, 11) as bidentate OO ligands, and imidazole or isocyanocyclohexane as monodentate ligands is reported. The complexes were synthesized by reacting the [NEt(4)](2)[Re(CO)(3)Br(3)] precursor with the β-diketone t...

For box dimensions (upper and lower), we consider the classical intermediate value question of dimension theory: is it true that in a metric compact space X α or lower) for any non-negative number β not exceeding α, there exists closed subset F whose corresponding equal to β? upper dimension, positive answer this was obtained joint work author O. V. Fomkina. However, statement general case lowe...

Membrane-assisted amyloid formation is implicated in human diseases, and many of the aggregating species accelerate amyloid formation and induce cell death. While structures of membrane-associated intermediates would provide tremendous insights into the pathology and aid in the design of compounds to potentially treat the diseases, it has not been feasible to overcome the challenges posed by th...