Mismatch discrimination in oligonucleotide hybridization reactions using single strand binding protein. A surface plasmon fluorescence study

We describe the use of surface plasmon- and surface plasmon fieldenhanced fluorescence spectroscopy for the detection of hybridization reactions between surface-attached probe oligonucleotides and complement strands binding from solution. These targets, exhibiting different base mismatches relative to the probe 15-mer sequences, carry a fluorophore at their 5'-end thus allowing for sensitive detection and quantification of association, k_on, and dissociation, k_off, rate constants, as well as affinity constants, K_a. We demonstrate that by the competitive binding / replacement of single strand binding proteins the mismatch discrimination can be further enhanced.     

Atmospheric trace gas analysis with cavity ring-down spectroscopy

Cavity ring-down spectroscopy (CRDS) is a highly sensitive laser absorption method. It can be used for quantitative analysis of molecular species at the sub-ppb level. The absorption cell (cavity) is sealed by two high-reflective mirrors on each side, which results in an effective absorption path-length of some kilometers. Our experiments for atmospheric gas analysis have been carried out so far with an Excimer pumped dye laser in the UV-VIS and a CO overtone sideband laser in the wavelength region around 3 μm. Experiments with an all solid-state difference frequency laser system will follow. In the UV-VIS region, we measured trace gas molecules like SO₂, NO₂, and CH₂O. In the mid-infrared, around 3 μm, we measured hydrocarbons like CH₄, C₂H₆, and C₂H₄ with a detection limit of less than 1 ppb. The noise equivalent absorption coefficients in the MIR are in the order of 1.7·10⁻⁹ cm⁻¹. Due to the high data acquisition rate and the high sensitivity, CRDS enables real-time detection of trace gases in ambient air.     

Anwendung der Merkmalsklassenanalyse auf feinkörnige Reststoffe aus der Eisen- und Stahlindustrie

Pyrometallurgical processes invariably yield large amounts of fine residues containing high grades of valuable elements, but often also of detrimental ones. Instead of being disposed of entirely they can be treated by means of mineral processing techniques and recycled, which requires prior characterisation of the dusts‘ relevant properties. A range of residues from iron and steel production was subject to fractional analysis. As common findings, magnetic separation is not able to split the valuable and detrimental elements in these samples whereas air classifying does work. Portability of this approach onto other metallurgical areas and other types of business is presumed.     

Motives for acquisitions among engineering consulting firms

Many empirical studies across various industry sectors show a high failure rate of mergers and acquisitions (M&A), suggesting that this instrument of corporate development is rather risky. Since engineering consulting firms usually have a low tangible asset base as well as good educated and highly mobile professionals, carrying out an M&A transaction in this particular service sector creates an even higher risk. It is evident from the relevant construction and engineering literature that a large number of engineering consulting firms engage in M&A for their corporate development. Owing to the uniqueness of that service sector combined with the high failure rate of M&A, a survey among the top 100 engineering consulting firms in Europe was conducted to investigate the motives behind M&A transactions. Findings suggest that diversification into new service/client markets as well as the penetration into new geographic markets were the most important motives. Further, increasing the firm's market share and the acceleration of growth were the next most popularly rated motives, while tax reasons or spending the firm's excess cash were both seen as relatively unimportant motives. The results show that - compared to other industry sectors - engineering consulting firms had some very different motives or another emphasis was placed on those motives when conducting an M&A transaction. Results also show that some motives were just as important for engineering consulting firms as for firms of other industry sectors, for example the increase of market share or the acceleration of firm growth.     

Untersuchungen zur Sorptionsreversibilität von organischen Schadstoffen in Aktivkohle, Holzkohle und Zeolith Y-200

Numerous studies have shown that sorption of organic contaminants in soils is dominated by the natural organic carbon content (C _org) of the soil. However, it is still under discussion whether sorption processes are fully reversible or whether an irreversibly sorbed contaminant fraction remains in the soil. This is especially important when considering soil remediation measures and its targets. In multi-stage sorption-desorption batch experiments with TCE, PCE, ortho-xylene and para-xylene and with the sorbents activated carbon, charcoal and a hydrophobic zeolite Y-200, the reversibility of sorption was studied. It could be shown that the structural features of the sorbents are of ample importance for the occurrence of a desorption-resistant fraction. While sorption was mainly reversible for the micro-porous zeolite Y-200 with a rigid pore network, charcoal and the activated carbon showed significant desorption hysteresis. However, following a subsequent sorption step, this fraction eventually desorbs and is re-mobilized.     

Artificial Maturation of the Highly Active Heterodimeric [FeFe] Hydrogenase from Desulfovibrio desulfuricans ATCC 7757

Hydrogenases catalyze the reduction of protons and oxidation of molecular hydrogen with high turnover frequencies and low overpotentials under ambient conditions. The heterodimeric [FeFe] hydrogenase from Desulfovibrio desulfuricans has an exceptionally high activity, and can be purified aerobically in an oxygen-stable inactive state. Recently, it was demonstrated that monomeric [FeFe] hydrogenases produced recombinantly in Escherichia coli can be artificially maturated by simply incubating the inactive “apo” enzymes with the synthetic [2Fe] cofactor mimic [Fe₂(adt)(CO)₄(CN)₂]²⁻. Here, we use the same technique to produce the heterodimeric “apo” hydrogenase from D. desulfuricans in E. coli with a high yield and purity, and maturate the “apo” enzyme with [Fe₂(adt)(CO)₄(CN)₂]²⁻ to generate fully active “holo” enzyme. Interestingly, the rate of the artificial maturation process with D. desulfuricans is significantly slower than that for all other hydrogenases tested so far. The artificially maturated enzyme is spectroscopically and electrochemically identical to the native enzyme and shows high rates of hydrogen production (3700 s⁻¹) and hydrogen oxidation (63,000 s⁻¹). We expect that our highly efficient production method will facilitate future studies of this enzyme and other related [FeFe] hydrogenases from Desulfovibrio species.     

Ultra-trace Analysis of Enantiomeric Impurities in Proteinogenic N-Fmoc-Amino-acid Samples on Cinchona Alkaloid-based Chiral Stationary Phases

The enantiomeric purity of N_α-Fmoc-protected amino acids is crucial from the viewpoint of peptide synthesis; therefore, a sensitive high-performance liquid chromatographic protocol was developed for the identification and quantification of enantiomeric impurities of commercially available N_α-Fmoc-protected amino acids on Cinchona alkaloid quinine- and quinidine-based weak anion exchanger-type chiral stationary phases. In the course of the evaluation of the chiral chromatographic method, the effect of the mobile phase composition, nature, and concentration of different additives were optimized. The specific phenomenon that quinine- and quinidine-based chiral stationary phases behave as pseudo-enantiomers permits that the sequence of elution of the enantiomers might be reversed by simple column switching. This is quite advantageous as regards the separation of the minor component in the presence of the major one. The method developed permits detection of less than 0.01 % enantiomeric impurity in the presence of the major enantiomer.     

Identification and Structure–Activity Relationship Studies of Small‐Molecule Inhibitors of the Methyllysine Reader Protein Spindlin1

The methyllysine reader protein Spindlin1 has been implicated in the tumorigenesis of several types of cancer and may be an attractive novel therapeutic target. Small‐molecule inhibitors of Spindlin1 should be valuable as chemical probes as well as potential new therapeutics. We applied an iterative virtual screening campaign, encompassing structure‐ and ligand‐based approaches, to identify potential Spindlin1 inhibitors from databases of commercially available compounds. Our in silico studies coupled with in vitro testing were successful in identifying novel Spindlin1 inhibitors. Several 4‐aminoquinazoline and quinazolinethione derivatives were among the active hit compounds, which indicated that these scaffolds represent promising lead structures for the development of Spindlin1 inhibitors. Subsequent lead optimization studies were hence carried out, and numerous derivatives of both lead scaffolds were synthesized. This resulted in the discovery of novel inhibitors of Spindlin1 and helped explore the structure–activity relationships of these inhibitor series.     

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

The selective wetting behavior of silica in emulsion styrene butadiene rubber (ESBR)/solution styrene butadiene rubber (SSBR) blends is characterized by the wetting concept, which is further developed for filled blends based on miscible rubbers. It is found that not only the chemical rubber–filler affinity but also the topology of the filler surface significantly influences the selective filler wetting in rubber blends. The nanopore structure of the silica surface has been recognized as the main reason for the difference in the wetting behavior of the branched ESBR molecules and linear SSBR molecules. However, the effect of nanopore structure becomes more significant in the presence of silane. It is discussed that the adsorption of silane on silica surface constricts the nanopore to some extent that hinders effectively the space filling of the nanopores by the branched ESBR molecules but not by the linear SSBR molecules. As a result, in silanized ESBR/SSBR blends the dominant wetting of silica surface by the tightly bonded layer of SSBR molecules causes a low‐energy dissipation in the rubber–filler interphase. That imparts the low rolling resistance to the blends similar to that of a silica‐filled SSBR compound, while the ESBR‐rich matrix warrants the good tensile behavior, i.e., good abrasion and wear resistance of the blends.