A Sulfhydryl-Reactive Ruthenium (II) Complex and Its Conjugation to Protein G as a Universal Reagent for Fluorescent Immunoassays

To develop a fluorescent ruthenium complex for biosensing, we synthesized a novel sulfhydryl-reactive compound, 4-bromophenanthroline bis-2,2′-dipyridine Ruthenium bis (hexafluorophosphate). The synthesized Ru(II) complex was crosslinked with thiol-modified protein G to form a universal reagent for fluorescent immunoassays. The resulting Ru(II)-protein G conjugates were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The emission peak wavelength of the Ru(II)-protein G conjugate was 602 nm at the excitation of 452 nm which is similar to the spectra of the Ru(II) complex, indicating that Ru(II)-protein G conjugates still remain the same fluorescence after conjugation. To test the usefulness of the conjugate for biosensing, immunoglobulin G (IgG) binding assay was conducted. The result showed that Ru(II)-protein G conjugates were capable of binding IgG and the more cross-linkers to modify protein G, the higher conjugation efficiency. To demonstrate the feasibility of Ru(II)-protein G conjugates for fluorescent immunoassays, the detection of recombinant histidine-tagged protein using the conjugates and anti-histidine antibody was developed. The results showed that the histidine-tagged protein was successfully detected with dose-response, indicating that Ru(II)-protein G conjugate is a useful universal fluorescent reagent for quantitative immunoassays

Tandem application of C-C bond-forming reactions with reductive ozonolysis

Several variants of reductive ozonolysis, defined here as the in situ generation of aldehydes or ketones during ozonolytic cleavage of alkenes, are demonstrated to work effectively in tandem with a number of C-C bond-forming reactions. For reactions involving basic nucleophiles (1,2- addition of Grignard reagents, Wittig or Horner-Emmons olefinations, and directed Aldol reactions of lithium enolates) the one-pot process offers a rapid and high-yielding alternative to traditional two-step protocols

High-Pressure Stability Of Carbonates - Quenching Of Calcite-II, High-Pressure Polymorph Of CaCO3

We present the results of a series of experiments on calcite I at around 45 GPa and temperatures between 300 and 2000 K, in a YAG-laser-heated diamond-anvil cell. Quenched samples have been examined by transmission electron microscopy. In the unheated part of the samples, calcite has been partially transformed into aragonite and preserved during quenching. This partial transformation must be related to the high deviatoric stresses present in the diamond anvil cell. In the heated parts of the samples aragonite, calcite-I and also calcite-II are observed. It is the first time that calcite-II has been quenched and characterized at ambient conditions. The sequence of formation, preservation or back-transformation during pressure and temperature quenching of the high-pressure polymorphs of CaCO3 in this kind of experiment is yet not completely elucidated, but several explanations are proposed to account for these observations

Raman-Spectroscopic Studies Of Carbonates .1. High-Pressure And High-Temperature Behavior Of Calcite, Magnesite, Dolomite And Aragonite

The room-temperature Raman spectra of aragonite, magnesite and dolomite have been recorded up to 30 GPa and 25 GPa, respectively and no phase changes were observed during compression, unlike calcite. The effect of temperature on the room-pressure Raman spectra of calcite, aragonite, magnesite and dolomite is reported up to 800-11 00 K. The measured relative pressure.and temperature-shifts of the Raman lines are greater for the lattice modes than for the internal modes of the CO3 groups. These shifts are used to calculate the mode anharmonic parameters of the observed Raman modes; they are negative and their absolute values are smaller (close to 0) for the internal CO3 modes than for the lattice modes (4-17 10(-5) K-1). The temperature shifts of the lattice modes in calcite are considerably larger than those for dolomite and magnesite, and a marked non-linear increase in linewidth is observed above 400-degrees-C for calcite. This is consistent with an increasing relaxational component to the libration of the CO3 groups about their threefold axes, premonitory to the rotational order-disorder transition at higher temperature. This behaviour is not observed for the other calcite structured minerals in this study. We examine systematic variations in the lattice mode frequencies and linewidths with composition, to begin to understand these differences in their anharmonic behaviour. Finally, we have used a simple Debye-Waller model to calculate atomic displacements in calcite, magnesite and dolomite with increasing temperature from the vibrational frequency data, to provide a direct comparison with atomic positional data from high-temperature structure refinements

Experimental-Evidence For Carbonate Stability In The Earths Lower Mantle

We present experimental results on the stability of carbonates up to 50 GPa and at high temperatures (1500-2500 K). The experiments were conducted in a laser-heated diamond anvil cell and the run products were characterized by analytical transmission electron microscopy. Dolomite is shown to break down to a CaCO3 + MgCO3 assemblage at pressures between 20 and 50 GPa. No decarbonatation was evident, suggesting that carbonates remain stable under these conditions with respect to rocksalt oxide + CO2 assemblages. Equimolar mixed powders of dolomite + enstatite and dolomite + olivine were transformed into magnesite + calcic perovskite and into magnesite + calcic and magnesian perovskites + magnesiowustite, respectively. The very strong partitioning of Ca in silicates suggests that magnesite is the stable carbonate in the presence of silicates in the Earth's lower mantle down to at least 1500 km. Finally, eutectoid or eutectic intergrowth of magnesiowustite and magnesite is observed, suggesting a possible mutual solubility between these two phases at high pressures and high temperatures. Lower mantle magnesiowustite may provide an alternative host for carbon in the Earth's lower mantle

Binding of L-glutamate to glutamate dehydrogenase in the presence of 1,4,5,6-tetrahydronicotinamide adenine dinucleotide

International audienceIn a previous work with Julliard, a lipid-protein complex showing a high affinity for glutamate was extracted from pig heart mitochondrial membranes; it exhibited many properties expected from a glutamate translocator [ 11. From its protein composition it was suggested..