scholarly journals Aggregation Behavior of Sodium Mono-n-Dodecyl Phosphate Surfactant in Aqueous Media, and Function in Catalytic Activity. I. Multi-Step Aggregates Formation and Catalytic Activity for Hydrolysis of p-Nitrophenyl Acetate in Aqueous Solution

2004 ◽  
Vol 53 (5) ◽  
pp. 247-265 ◽  
Author(s):  
Kyoyu NAKAYAMA ◽  
Isao TARI ◽  
Masashi SAKAI ◽  
Yoshio MURATA ◽  
Gohsuke SUGIHARA
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Aqueous Media ◽  
Aggregation Behavior ◽  
And Function ◽  
Hydrolysis Of

Synthesis of Ni/Au/Co trimetallic nanoparticles and their catalytic activity for hydrogen generation from alkaline sodium borohydride aqueous solution

RSC Advances ◽  
2015 ◽  
Vol 5 (43) ◽  
pp. 34364-34371 ◽  
Author(s):  
Chengpeng Jiao ◽  
Zili Huang ◽  
Xiaofeng Wang ◽  
Haijun Zhang ◽  
Lilin Lu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Sodium Borohydride ◽  
Hydrogen Generation ◽  
Co Nanoparticles ◽  
Hydrolysis Of ◽  
Positively Charged

Alloyed Ni/Au/Co nanoparticles with negatively-charged Au, Co atoms, and positively-charged Ni atoms were prepared as effective catalysts for hydrolysis of NaBH4.

scholarly journals Transfer Hydrogenation Reactions of Photoactivatable N,N’-Chelated Ruthenium(II) Arene Complexes

2017 ◽  
Vol 57 (3) ◽  
Author(s):  
Soledad Betanzos-Lara ◽  
Abraha Habtemariam ◽  
Peter J. Sadler
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Sodium Formate ◽  
Transfer Hydrogenation ◽  
Arene Complexes ◽  
Chelating Ligand ◽  
Spontaneous Hydrolysis ◽  
Hydrogenation Reactions ◽  
Excess Sodium ◽  
Hydrolysis Of

We show that the reaction of Ru<sup>II</sup> arene chlorido complexes of the type [(η<sup>6</sup>-arene)Ru(N,N’)Cl]<sup>+</sup> arene = p-cymene (pcym), hexamethylbenzene (hmb), indane (ind), <em>N,N’</em> = bipyrimidine (bpm) and 1,10-phenanthroline (phen) with excess sodium formate generates a very stable formate adduct through spontaneous hydrolysis of the Ru-Cl bond at 310 K and pH* = 7.0. The formate adducts are also produced when Ru<sup>II</sup> arene pyridine complexes of the type [(η<sup>6</sup>-arene)Ru(N,N’)(Py)]<sup>2+</sup> (where Py = pyridine), are irradiated with UVA (λ<sub>irr</sub> = 300-400 nm) or visible light (λ<sub>irr</sub> = 400-660 nm) under the same conditions. The Ru<sup>II</sup> arene formato adducts do not catalyse the reduction of acetone through transfer hydrogenation. However, all the complexes (except complex <strong>2</strong> which contains phen as the chelating ligand) can catalyse the regioselective reduction of NAD<sup>+</sup> in the presence of formate (25 mol equiv) in aqueous solution to form 1,4-NADH. The catalytic activity is dependent on the nature of the chelating ligand. Most interestingly, the regioselective reduction of NAD+ to 1,4-NADH can be also specifically triggered by photoactivating a RuII arene Py complex.

scholarly journals High catalytic activity of Rh nanoparticles generated from cobaltocene and RhCl3 in aqueous solution

2019 ◽  
Vol 6 (10) ◽  
pp. 2704-2708 ◽  
Author(s):  
Wenjuan Wang ◽  
Roberto Ciganda ◽  
Changlong Wang ◽  
Ane Escobar ◽  
Angel M. Martinez-Villacorta ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Transfer Hydrogenation ◽  
High Catalytic Activity ◽  
Hydrolysis Of

Cobalticinium chloride-stabilized RhNPs are very efficient catalysts for hydrolysis of H3N-BH3, reduction of 4-NP, hydrogenation of benzene and transfer hydrogenation.

scholarly journals The role of β-hairpin conformation in ester hydrolysis peptide catalysts based on a TrpZip scaffold

RSC Advances ◽  
2021 ◽  
Vol 11 (38) ◽  
pp. 23714-23718
Author(s):  
Xinyu Liu ◽  
Riley Waters ◽  
Hannah E. Gilbert ◽  
Gage T. Barroso ◽  
Kelsey M. Boyle ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Aqueous Media ◽  
Ester Hydrolysis ◽  
Peptide Catalysts ◽  
Hairpin Conformation ◽  
Hydrolysis Of

Peptide catalysts based on TrpZip scaffolds for the hydrolysis of para-nitrophenylacetate in aqueous media were found to have higher catalytic activity in sequences without β-hairpin character.

scholarly journals Mutagenesis of Zinc Ligand Residue Cys221 Reveals Plasticity in the IMP-1 Metallo-β-Lactamase Active Site

2012 ◽  
Vol 56 (11) ◽  
pp. 5667-5677 ◽  
Author(s):  
Lori B. Horton ◽  
Sreejesh Shanker ◽  
Rose Mikulski ◽  
Nicholas G. Brown ◽  
Kevin J. Phillips ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Complete Removal ◽  
Zinc Binding ◽  
Saturation Mutagenesis ◽  
Content Type ◽  
Binding Residue ◽  
And Function ◽  
Enzyme Structure And Function ◽  
Hydrolysis Of

ABSTRACTMetallo-β-lactamases catalyze the hydrolysis of a broad range of β-lactam antibiotics and are a concern for the spread of drug resistance. To analyze the determinants of enzyme structure and function, the sequence requirements for the subclass B1 IMP-1 β-lactamase zinc binding residue Cys221 were tested by saturation mutagenesis and evaluated for protein expression, as well as hydrolysis of β-lactam substrates. The results indicated that most substitutions at position 221 destabilized the enzyme. Only the enzymes containing C221D and C221G substitutions were expressed well inEscherichia coliand exhibited catalytic activity toward β-lactam antibiotics. Despite the lack of a metal-chelating group at position 221, the C221G enzyme exhibited high levels of catalytic activity in the presence of exogenous zinc. Molecular modeling suggests the glycine substitution is unique among substitutions in that the complete removal of the cysteine side chain allows space for a water molecule to replace the thiol and coordinate zinc at the Zn2 zinc binding site to restore function. Multiple methods were used to estimate the C221G Zn2 binding constant to be 17 to 43 μM. Studies of enzyme functionin vivoinE. coligrown on minimal medium showed that both IMP-1 and the C221G mutant exhibited compromised activity when zinc availability was low. Finally, substitutions at residue 121, which is the IMP-1 equivalent of the subclass B3 zinc-chelating position, failed to rescue C221G function, suggesting the coordination schemes of subclasses B1 and B3 are not interchangeable.

Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution

2020 ◽  
Vol 56 (27) ◽  
pp. 3851-3854 ◽  
Author(s):  
Xiaomin Chai ◽  
Hai-Hua Huang ◽  
Huiping Liu ◽  
Zhuofeng Ke ◽  
Wen-Wen Yong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Performance ◽  
Aqueous Media ◽  
Highly Efficient ◽  
Co Conversion

A Co-based complex displayed the highest photocatalytic performance for CO2 to CO conversion in aqueous media.

Reactions in Activated Peroxide Systems and their Influences on Bleaching Performance

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiaoyan Wang ◽  
Jinmei Du ◽  
Changhai Xu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Energy Efficiency ◽  
Textile Industry ◽  
High Energy ◽  
Side Reactions ◽  
Competitive Reactions ◽  
High Energy Efficiency ◽  
Hydrolysis Of ◽  
Bleach Activators

Abstract:: Activated peroxide systems are formed by adding so-called bleach activators to aqueous solution of hydrogen peroxide, developed in the seventies of the last century for use in domestic laundry for their high energy efficiency and introduced at the beginning of the 21st century to the textile industry as an approach toward overcoming the extensive energy consumption in bleaching. In activated peroxide systems, bleach activators undergo perhydrolysis to generate more kinetically active peracids that enable bleaching under milder conditions while hydrolysis of bleach activators and decomposition of peracids may occur as side reactions to weaken the bleaching efficiency. This mini-review aims to summarize these competitive reactions in activated peroxide systems and their influence on bleaching performance.

Immobilized Nanoparticles-Mediated Enzymatic Hydrolysis of Cellulose for Clean Sugar Production: A Novel Approach

2019 ◽  
Vol 15 (3) ◽  
pp. 296-303 ◽  
Author(s):  
Swapnil Gaikwad ◽  
Avinash P. Ingle ◽  
Silvio Silverio da Silva ◽  
Mahendra Rai
Keyword(s):  
Catalytic Activity ◽  
Enzymatic Hydrolysis ◽  
Immobilized Enzyme ◽  
Free Enzyme ◽  
Magnetic Nanomaterials ◽  
Sugar Production ◽  
Cellulase Enzyme ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

Background: Enzymatic hydrolysis of cellulose is an expensive approach due to the high cost of an enzyme involved in the process. The goal of the current study was to apply magnetic nanomaterials as a support for immobilization of enzyme, which helps in the repeated use of immobilized enzyme for hydrolysis to make the process cost-effective. In addition, it will also provide stability to enzyme and increase its catalytic activity. Objective: The main aim of the present study is to immobilize cellulase enzyme on Magnetic Nanoparticles (MNPs) in order to enable the enzyme to be re-used for clean sugar production from cellulose. Methods: MNPs were synthesized using chemical precipitation methods and characterized by different techniques. Further, cellulase enzyme was immobilized on MNPs and efficacy of free and immobilized cellulase for hydrolysis of cellulose was evaluated. Results: Enzymatic hydrolysis of cellulose by immobilized enzyme showed enhanced catalytic activity after 48 hours compared to free enzyme. In first cycle of hydrolysis, immobilized enzyme hydrolyzed the cellulose and produced 19.5 ± 0.15 gm/L of glucose after 48 hours. On the contrary, free enzyme produced only 13.7 ± 0.25 gm/L of glucose in 48 hours. Immobilized enzyme maintained its stability and produced 6.15 ± 0.15 and 3.03 ± 0.25 gm/L of glucose in second and third cycle, respectively after 48 hours. Conclusion: This study will be very useful for sugar production because of enzyme binding efficiency and admirable reusability of immobilized enzyme, which leads to the significant increase in production of sugar from cellulosic materials.

Decomposition of hydrogen peroxide on a two-component NiO-CdO catalyst and the effect of ionizing radiation on its catalytic properties

1979 ◽  
Vol 44 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Catalytic Properties ◽  
Cadmium Oxide ◽  
Chemisorb Oxygen ◽  
Composition Region ◽  
Chemisorbed Oxygen ◽  
Two Component

The catalytic properties of two-component catalyst nickel oxide-cadmium oxide with the proportions of the components covering the whole composition region 0-100% were examined by studying the decomposition of hydrogen peroxide in aqueous solution on it. In the range 0-25 mol.% CdO, cadmium oxide is found to affect infavourably the ability of nickel oxide to chemisorb oxygen. The amount of the chemisorbed oxygen increases several times on gamma irradiation of the samples. The effect of cadmium oxide on the catalytic activity of the system shows up in fresh samples only indirectly via the changed amount of the oxygen chemisorbed. In older samples the initial catalytic activity of the system is changed, which can be explained based on the concept of bivalent catalytic centres in terms of the co-action of the catalytic centres of the two oxides, which are in equilibrium. The irradiation of the system under study speeds up the processes leading to the establishing of this equilibrium which is thermally very stable, and results in a substantial increase of the catalytic activity of the samples investigated.

Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

1983 ◽  
Vol 29 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
M W McGowan ◽  
J D Artiss ◽  
B Zak
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Amniotic Fluid ◽  
Enzymatic Reaction ◽  
Detergent Solution ◽  
Enzymatic Determination ◽  
Red Color ◽  
Hydrolysis Of ◽  
Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

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