Search results for "Reducing agent"
showing 10 items of 51 documents
Identification of Two Mannoproteins Released from Cell Walls of a Saccharomyces cerevisiae mnn1 mnn9 Double Mutant by Reducing Agents
1999
The cell wall of Saccharomyces cerevisiae represents some 30% of the total weight of the cell and is made up of β-glucans, mannose-containing glycoproteins (mannoproteins), and small amounts of chitin (9, 15). The mannoproteins can be divided into three groups according to the linkages that bind them to the structure of the cell wall: (i) noncovalently bound, (ii) covalently bound to the structural glucan, and (iii) disulfide bound to other proteins that are themselves covalently bound to the structural glucan of the cell wall (8). Our work has focused on the disulfide-bound mannoproteins, probably the least well known of the three groups mentioned above. Previous work (25) showed that trea…
Pulicaria glutinosa plant extract: a green and eco-friendly reducing agent for the preparation of highly reduced graphene oxide
2014
The environmentally friendly synthesis of nanomaterials using green chemistry has attracted tremendous attention in recent years due to its easy handling, low cost, and biocompatibility. Here we demonstrate a facile and efficient route for the synthesis of highly reduced graphene oxide (PE-HRG) by the green reduction of graphene oxide (GRO) using the Pulicaria glutinosa plant extract (PE). The phytomolecules present in the P. glutinosa extract are not only responsible for the reduction of GRO, but also for the functionalization of the surface of the PE-HRG nanosheets and stabilize them in various solvents, thereby limiting the use of any other external and harmful chemical reductants and su…
Hydrogen: a good partner for rhodium-catalyzed hydrosilylation
2014
The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)-SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation…
Stimulation of Fe-S cluster insertion into apoFNR by Escherichia coli glutaredoxins 1, 2 and 3 in vitro.
2004
Abstract The oxygen sensor fumarate nitrate reductase regu-lator (FNR) of Escherichia coli contains in the active (anaerobic)state a [4Fe–4S] 2þ cluster which is lost after exposure to O 2 .Inaerobically prepared apoFNR, or in FNR obtained by treatmentof [4Fe–4S] FNR with O 2 in vitro, intramolecular cysteinedisulfides are found, including the cysteine residues which serveas ligands for the Fe–S cluster. It is shown here that thereconstitution of [4Fe–4S] FNR from this form of aerobicapoFNR was preceded by a long lag phase when glutathione wasused as the reducing agent. Addition of E. coli glutaredoxins(Grx) 1, 2 or 3 decreased the lag phase greatly and stimulatedthe reconstitution rate slig…
Effect of reducing agents on the acidification capacity and the proton motive force of Lactococcus lactis ssp. cremoris resting cells.
2002
International audience; Reducing agents are potential inhibitors of the microbial growth. We have shown recently that dithiothreitol (DTT), NaBH(4) and H(2) can modify the proton motive force of resting cells of Escherichia coli by increasing the membrane protons permeability [Eur. J. Biochem. 262 (1999) 595]. In the present work, the effect of reducing agents on the resting cells of Lactococcus lactis ssp. cremoris, a species widely employed in dairy processes was investigated. DTT did not affect the acidification nor the DeltapH, in contrast to the effect previously reported on E. coli. The DeltaPsi was slightly increased (30 mV) at low pH (pH 4) in the presence of 31 mM DTT or 2.6 mM NaB…
Double Drug Delivery Using Capped Mesoporous Silica Microparticles for the Effective Treatment of Inflammatory Bowel Disease
2019
[EN] Silica mesoporous microparticles loaded with both rhodamine B fluorophore (S1) or hydrocortisone (S2), and capped with an olsalazine derivative, are prepared and fully characterized. Suspensions of Si and S2 in water at an acidic and a neutral pH show negligible dye/drug release, yet a notable delivery took place when the reducing agent sodium dithionite is added because of hydrolysis of an azo bond in the capping ensemble. Additionally, olsalazine fragmentation induced 5-aminosalicylic acid (5-ASA) release. In vitro digestion models show that S1 and S2 solids are suitable systems to specifically release a pharmaceutical agent in the colon. In vivo pharmacokinetic studies in rats show …
Disulfide bridge formation between C1q and IgG in vitro.
1990
The globular heads of C1q are known to possess free-SH groups. Here we show that these groups, which are concealed in the native molecule, are exposed by interaction of C1q with dialysis membrane. During iodination, I+ and I2 oxidize these sulfhydryls to produce disulfide-linked C1q aggregates. Approximately 15% of C1q bound to immunoglobulin aggregates is resistant to high conductivity elution and reducing agent is required to release it. These data show that dialysis, adsorption to Ig and iodination of C1q result in structural and functional changes in the molecule, and suggest a mechanism by which these changes occur. Disulfide bridging between C1q and IgG in vitro suggests that this may…
Effective low temperature reduction of graphene oxide with vanadium(iii)
2014
Reduction of graphene oxide (GO) with vanadium(III) trichloride under various reaction conditions has been investigated. The results show that V(III) can be used as an efficient reducing agent for GO in aqueous solutions at low concentrations and in moderate temperatures under ambient conditions. The IR spectroscopy and X-ray photoelectron spectroscopy (XPS) show that the structure of the vanadium-reduced material is similar to reduced graphene oxide prepared using TiCl3 or hydrazine as a reducing agent. The electrical conductivity of the material is also similar in all cases. However, on the basis of the XPS results, vanadium-based reduction does not leave significant reductant impurities …
Formation and Growth of Pd Nanoparticles Inside a Highly Cross-Linked Polystyrene Support: Role of the Reducing Agent
2014
Simultaneous time-resolved SAXS and XANES techniques were employed to follow in situ the formation of Pd nanoparticles in a porous polystyrene support, using palladium acetate as a precursor and gaseous H2 or CO as reducing agents. These results, in conjunction with data obtained by diffuse reflectance UV–vis and DRIFT spectroscopy and TEM measurements, allowed unraveling of the different roles played by gaseous H2 and CO in the formation of the Pd nanoparticles. In particular, it was found that the reducing agent affects (i) the reduction rate (which is faster in the presence of CO) and (ii) the properties of the hosted nanoparticles, in terms of size (bigger with CO), morphology (spherica…
Oxide-based nanomaterials for fuel cell catalysis:the interplay between supported single Pt atoms and particles
2017
The concept of single atom catalysis offers maximum noble metal efficiency for the development of low-cost catalytic materials. Among possible applications are catalytic materials for proton exchange membrane fuel cells. In the present review, recent efforts towards the fabrication of single atom catalysts on nanostructured ceria and their reactivity are discussed in the prospect of their employment as anode catalysts. The remarkable performance and the durability of the ceria-based anode catalysts with ultra-low Pt loading result from the interplay between two states associated with supported atomically dispersed Pt and sub-nanometer Pt particles. The occurrence of these two states is a co…