Catalytic activity

A reaction happens need the energy to vibrate the molecules and the reactant concentration enough. The energy here is often provided by heat. However, in living system, high temperature may harm the biological structure Truly that the concentration in living system is very low. So living organisms solve these problems by using enzyme

94p zingzing09 21-10-2012 68 10   Download

Objective of the study: The general objective of this study is to produce catalysts of bimetallic oxides (Cu-Co), on porous materials (activated carbon, silica gel, MCM-41) to adsorb and oxidize VOCs, which is represented by toluene, a popular VOCs with particular properties of the BTEX group in many industrial factories, at low temperature.

144p armyofthedead 23-06-2021 23 3   Download

Research purpose: Using computational chemistry methods to study the mechanism of hydrogenation CO on the transition metal catalyst systems of Ni, Cu, Co, bimetallic catalysts NiCu, CoCu and catalytic systems bearing cluster on oxide carriers: MgO, Al2O3 and activated carbon (AC); compare and clarify the role of catalyst centers in single or bimetallic catalyst systems; clarifies the role of carriers (MgO, Al2O3 and AC) in the hydrogenation of CO.

27p thebadguys 08-06-2021 27 4   Download

Successfully synthesized nano – mixed oxide by different gelling agents; compared, selected the appropriate gelling agent; researched to evaluate the catalytic activity of mixed oxide nanoparticles formed with pollutants methyl orange (MO), methylene blue (MB). Successful dispersed mixed oxide nanoparticles on rGO; investigated catalytic activity of material systems on parathion, fenitrothion.

28p capheviahe26 25-01-2021 35 5   Download

The catalyst 7.5% NiO/TiO2 and seven samples of NiO/γ-Al2O3 with NiO content from 7.5% to 60% have been obtained and studied. Physico-chemical characteristics of the catalysts were determined by methods of Adsorption (BET), X-ray Diffraction (XRD), TemperatureProgrammed Reduction (TPR) and Hydrogen Pulse Titration. The catalytic properties of the obtained samples were investigated in the reaction of CO methanation at temperatures 180 – 220◦C and mole ratios hydrogen/carbon monoxide 25-100.

16p 12120609 01-06-2020 9 1   Download

The work has been carried out under thermal solvent free conditions. Mg/Fe = 3 hydrotalcite heterogeneous solid catalyst offers simple means of recovery and the isolated catalyst was reused for number of times without significant loss of catalytic activity.

14p tocectocec 25-05-2020 8 2   Download

Recovering useful hydrocarbons from sewage sludge using zirconia-supporting iron oxide catalysts was investigated. Zirconia has activity for decomposing water molecules to generate active oxygen and hydrogen species.

6p tuananhhumg 04-11-2013 38 3   Download

In petroleum industry, it is desirable to produce lighter hydrocarbons such as gasoline, kerosene and gas–oil from unused heavy oils. Thus we have developed zirconia-supporting iron oxide catalysts View the MathML source to decompose petroleum residual oil (atmospheric distilled residual oil) with steam.

6p tuananhhumg 04-11-2013 59 3   Download

A new method for the synthesis of nanosized zeolites in organic solvents, such as formamide and toluene as crystallization medium instead of water, in the presence of organosilane has been developed. Organic solvents have a great impact on the synthesis of nanozeolites.

9p tuananhhumg 04-11-2013 57 4   Download

The effects of addition of alumina to the matrices of cracking catalysts containing different types of zeolite Y, on their cracking performance, were investigated using a micro activity test and two different feed oils.

13p tuananhhumg 04-11-2013 52 4   Download

The importance of two putative Zn2+-binding (Asp347, Glu429) and two catalytic (Arg431, Lys354) residues in the tomato leucine aminopeptidase (LAP-A) function was tested. The impact of substitutions at these positions, corresponding to the bovine LAP residues Asp255, Glu334, Arg336, and Lys262, was evaluated in His6–LAP-A fusion proteins expressed in Escherichia coli. Sixty-five percent of the mutant His6–LAP-A proteins were unstable or had complete or partial defects in hexamer assembly or stability. The activity of hexameric His6–LAP-As on Xaa-Leu and Leu-Xaa dipeptides was tested.

11p system191 01-06-2013 44 4   Download

Pyruvate decarboxylase (EC 4.1.1.1) was isolated and purified from the yeast Kluyveromyces lactis. The properties of this enzyme relating to the native oligomeric state, the subunit size, the nucleotide sequence of the coding gene(s), the catalytic activity, and protein fluorescence as well as circular dichroism are very similar to those of the well characterized pyruvate decarboxylase species from yeast.

8p system191 01-06-2013 44 3   Download

To examine the role of the distal His42 residue in the catalytic mechanism of pea cytosolic ascorbate peroxidase, two site-directed variants were prepared in which His42 was replaced with alanine (H42A) or glutamic acid (H42E). Electronic spectra of the ferric derivatives of H42A and H42E (pH 7.0, l ¼ 0.10 M, 25.0 °C) revealed wavelength maxima [kmax (nm): 397, 509, % 540sh, 644 (H42A); 404, 516, % 538sh, 639 (H42E)] consistent with a predominantly fiveco-ordinate high-spin iron. The specific activity of H42E for oxidation of L-ascorbate (8.2 ± 0.

11p system191 01-06-2013 40 4   Download

In the biosynthesis of the antiarrhythmic alkaloid ajmaline, polyneuridine aldehyde esterase (PNAE) catalyses a central reaction by transforming polyneuridine aldehyde into epivellosimine, which is the immediate precursor for the synthesis of the ajmalane skeleton. The PNAE cDNA was previously heterologously expressed in E. coli. Sequence alignments indicated that PNAE has a 43% identity to a hydroxynitrile lyase from Hevea brasiliensis, which is a member of the a/b hydrolase superfamily. The catalytic triad, which is typical for this family, is conserved.

8p system191 01-06-2013 36 4   Download

a-Sarcin, a cyclizing ribonuclease secreted by the mould Aspergillus giganteus, is one of the best characterized members of a family of fungal ribotoxins. This protein induces apoptosis in tumour cells due to its highly specific activity on ribosomes. Fungal ribotoxins display a threedimensional protein fold similar to those of a larger group of microbial noncytotoxic RNases, represented by RNases T1 and U2.

7p system191 01-06-2013 27 3   Download

This study reports the identification and characterization of the regulatory subunit, TbRSU, of protein kinase A of the parasitic protozoon Trypanosoma brucei. TbRSU is coded for by a single copy gene. The protein contains an unusually long N-terminal domain, the pseudosubstrate site involved in binding and inactivation of the catalytic subunit, and two C-terminally located, closely spaced cyclic nucleotide binding domains.

10p system191 01-06-2013 39 4   Download

The aim of this study was to increase the stability of the thermolabile (ba)8-barrel enzyme indoleglycerol phosphate synthase from Escherichia coli by the introduction of disulfide bridges. For the design of such variants, we selected two out of 12 candidates, in which newly introduced cysteines potentially form optimal disulfide bonds. These variants avoid short-range connections, substitutions near catalytic residues, and crosslinks between the new and the three parental cysteines.

9p research12 01-06-2013 41 4   Download

By replacing specific amino acids at positions 112, 147 and 152 of the human aldosterone synthase (CYP11B2) with the corresponding residues from human, mouse or rat 11b-hydroxylase (CYP11B1), we have been able to investigate whether these residues belong to structural determinants of individual enzymatic activities. When incubated with 11-deoxycorticosterone (DOC), the 11b-hydroxylation activity of the mutants was most effectively increased by combining D147E and I112P (sixfold increase).

10p research12 01-06-2013 38 5   Download

Eukaryotic ribonuclease (RNase) H2 consists of one catalytic and two accessory subunits. Several single mutations in any one of these subunits of human RNase H2 cause Aicardi–Goutie`res syndrome. To examine whether these mutations affect the complex stability and activity of RNase H2, three mutant proteins of His-tagged Saccharomyces cerevisiaeRNase H2 (Sc-RNase H2*) were constructed. Sc-G42S*, Sc-L52R*, and Sc-K46W* contain single mutations in Sc-Rnh2Ap*, Sc-Rnh2Bp*, and Sc-Rnh2Cp*, respectively....

14p research12 29-04-2013 40 1   Download

The Rv0948c gene fromMycobacterium tuberculosisH37Rv encodes a 90 amino acid protein as the natural gene product with chorismate mutase (CM) activity. The protein, 90-MtCM, exhibits Michaelis–Menten kinetics with akcat of 5.5 ± 0.2 s )1 and a Kmof 1500 ± 100lmat 37C and pH 7.5. The 2.0 A˚ X-ray structure shows that 90-MtCM is an alla-helical homodimer (Protein Data Bank ID: 2QBV) with the topology ofEscheri-chia coliCM (EcCM), and that both protomers contribute to each catalytic site.

12p research12 29-04-2013 41 3   Download