scholarly journals POLYMERIC SUPPORTS FOR ENZYMES IMMOBILIZATION IN SYNTHESIS OF BIOLOGICALLY ACTIVE COMPOUNDS

2020 ◽  
Vol 64 (1) ◽  
pp. 67-72
Author(s):  
Olga V. Grebennikova ◽  
Anastasiya N. Mikhailova ◽  
Vladimir P. Molchanov ◽  
Aleksandrina M. Sulman ◽  
Valentin Yu. Doluda ◽  
...  
Keyword(s):  
Covalent Binding ◽  
Biologically Active ◽  
Positive Contribution ◽  
Optimal Conditions ◽  
Covalent Bonds ◽  
Polymer Supports ◽  
Covalent Crosslinking ◽  
Sorption Ability ◽  
High Sorption ◽  
Polymeric Supports

The report presents the synthesis of biocatalysts based on horseradish peroxidase immobilized on commercially available polymeric supports: hyper cross-linked polystyrene MN-100 and Sepabeads EC-HA. The immobilization was carried out by covalent crosslinking of the enzyme with the support using glutaraldehyde. The optimal amount of glutaraldehyde for covalent binding of HRP was found to be 0.2 g/l. The peroxidase/MN-100 and peroxidase/Sepabeads EC-HA biocatalysts presented in the work showed good activity in the oxidation of 2-methylnaphthol to 2 methyl-1,4-naphthohydroquinone (vitamin K4). The biocatalyst based on MN-100 showed higher activity compared to the biocatalyst based on Sepabeads EC-HA, which is likely due to the different surface structure of the original polymer supports. The samples retained their activity in ten consecutive reuses. The high reusability of peroxidase/MN-100 and peroxidase/Sepabeads EC-HA is explained by the high sorption ability of commercial polymer supports MN-100 and Sepabeads EC-HA and the formation of strong covalent bonds between the enzyme and the support. The optimal conditions for the oxidation of 2-methylnaphthol to 2-methyl-1,4-naphthohydroquinone using synthesized biocatalytic systems were also selected. The temperature of 40 °C and pH 7.2 were found to be optimal for the oxidation of the proposed substrate. The presented results will undoubtedly make a positive contribution to the development of the chemical and pharmaceutical industry.

scholarly journals Synthesis of Silver-Impregnated Magnetite Mesoporous Silica Composites for Removing Iodide in Aqueous Solution

Toxics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 175
Author(s):  
Sang-Eun Jo ◽  
Jung-Weon Choi ◽  
Sang-June Choi
Keyword(s):  
Aqueous Solution ◽  
Langmuir Isotherm ◽  
High Surface ◽  
High Surface Area ◽  
High Capacity ◽  
Maximum Adsorption Capacity ◽  
Initial Contact ◽  
Order Kinetic ◽  
Sorption Ability ◽  
High Sorption

Mag@silica-Ag composite has a high sorption ability for I− in aqueous solution due to its high surface area and strong affinity for the studied anion. The material adsorbed I− rapidly during the initial contact time (in 45 min, η = 80%) and reached adsorption equilibrium after 2 h. Moreover, mag@silica-Ag proved to selectively remove I− from a mixture of Cl−, NO3− and I−. The adsorption behavior fitted the Langmuir isotherm perfectly and the pseudo-second-order kinetic model. Based on the Langmuir isotherm, the maximum adsorption capacity of mag@silica-Ag was 0.82 mmol/g, which is significantly higher than previously developed adsorbents. This study introduces a practical application of a high-capacity adsorbent in removing radioactive I− from wastewaters.

scholarly journals Copper Ions Removal from Water using A2B3 Type Hyperbranched Poly(amidoamine) Hydrogel Particles

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3866
Author(s):  
Hojung Choi ◽  
Youngsik Eom ◽  
Sanghwa Lee ◽  
Sang Youl Kim
Keyword(s):  
Metal Ion ◽  
Copper Ions ◽  
Suspension Polymerization ◽  
Spherical Shape ◽  
Synthetic Process ◽  
Metal Ion Removal ◽  
Hyperbranched Poly ◽  
Sorption Ability ◽  
Heavy Metal Ion Removal ◽  
High Sorption

Micrometer-sized hyperbranched poly(amidoamine) (hPAMAM) particles are prepared with a simple A2B3 type Aza–Michael addition reaction between aminoethylpiperazine (AEP) and methylenebisacrylamide (MBA) in an inverse suspension polymerization condition. The synthesized particles exhibited surprisingly high Cu2+ sorption capacity (0.223g/g) for a solid-type absorbent. In addition to the high sorption ability of the particle, its simple synthetic process and convenience, due to its micrometer-sized spherical shape and recyclability, make it a practical and attractive absorbent for heavy metal ion removal from aqueous solutions.

scholarly journals Covalent crosslinking of von Willebrand factor to fibrin

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 95-101 ◽  
Author(s):  
M Hada ◽  
M Kaminski ◽  
P Bockenstedt ◽  
J McDonagh
Keyword(s):  
Von Willebrand Factor ◽  
Initial Rate ◽  
Factor Xiiia ◽  
Covalent Bonds ◽  
Covalent Crosslinking ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Plasmin Inhibitor

Abstract Factor XIIIa crosslinks a limited number of substrates via epsilon(gamma-glutamyl)-lysyl bond formation. It crosslinks fibrin to itself, alpha 2-plasmin inhibitor and fibronectin to fibrin, and fibronectin to collagen. Results presented here show that plasma von Willebrand factor (vWF) is a substrate for factor XIIIa and can be crosslinked to fibrin during gel formation. vWF-fibrin crosslinking was studied in purified systems and in plasma with 125I-vWF and 131I- fibrinogen. vWF incorporation into fibrin increased with time or increasing factor XIIIa. After electrophoresis of dissolved clots, distribution of 125I and 131I was measured and showed that vWF was crosslinked to the alpha chain of fibrin and entered the high-mol-wt alpha polymer. vWF-fibrin crosslinking decreased the initial rate of alpha polymer formation. Crosslinking of vWF polymer to itself could not be demonstrated under physiologic conditions but occurred if vWF was reduced first. Factor XIIIa catalyzed incorporation of putrescine into both monomeric and polymeric vWF. Altogether, these studies indicate that factor XIIIa can readily form covalent bonds between glutamine in vWF and lysine in fibrin alpha chains. This reaction occurs readily in vitro when plasma clotting is slow and may occur in vivo under similar conditions.

scholarly journals The role of double covalent flavin binding in chito-oligosaccharide oxidase from Fusarium graminearum

2008 ◽  
Vol 413 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Dominic P. H. M. Heuts ◽  
Remko T. Winter ◽  
Gerke E. Damsma ◽  
Dick B. Janssen ◽  
Marco W. Fraaije
Keyword(s):  
Redox Potential ◽  
Fusarium Graminearum ◽  
Covalent Binding ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
Covalent Bonds ◽  
Regioselective Oxidation ◽  
Flavin Binding ◽  
High Redox Potential

ChitO (chito-oligosaccharide oxidase) from Fusarium graminearum catalyses the regioselective oxidation of N-acetylated oligosaccharides. The enzyme harbours an FAD cofactor that is covalently attached to His94 and Cys154. The functional role of this unusual bi-covalent flavin–protein linkage was studied by site-directed mutagenesis. The double mutant (H94A/C154A) was not expressed, which suggests that a covalent flavin–protein bond is needed for protein stability. The single mutants H94A and C154A were expressed as FAD-containing enzymes in which one of the covalent FAD–protein bonds was disrupted relative to the wild-type enzyme. Both mutants were poorly active, as the kcat decreased (8.3- and 3-fold respectively) and the Km increased drastically (34- and 75-fold respectively) when using GlcNac as the substrate. Pre-steady-state analysis revealed that the rate of reduction in the mutant enzymes is decreased by 3 orders of magnitude when compared with wild-type ChitO (kred=750 s−1) and thereby limits the turnover rate. Spectroelectrochemical titrations revealed that wild-type ChitO exhibits a relatively high redox potential (+131 mV) and the C154A mutant displays a lower potential (+70 mV), while the H94A mutant displays a relatively high potential of approximately +164 mV. The results show that a high redox potential is not the only prerequisite to ensure efficient catalysis and that removal of either of the covalent bonds may perturb the geometry of the Michaelis complex. Besides tuning the redox properties, the bi-covalent binding of the FAD cofactor in ChitO is essential for a catalytically competent conformation of the active site.

scholarly journals SPECTROPHOTOMETRIC DETERMINATION OF ANTIOXIDANT SODIUM METABISULPHITE CONTENT IN PREPARED MEDICINAL FORMS OF VETERINARY MEDICINAL PRODUCTS

2020 ◽  
Vol 21 (2) ◽  
pp. 189-198
Author(s):  
H. Yu. Teslyar ◽  
M. Ya. Smolinska ◽  
I. Ya. Kotsyumbas ◽  
N. M. Chyhyn ◽  
N. G. Rohulia ◽  
...  
Keyword(s):  
Spectrophotometric Determination ◽  
Storage Time ◽  
Analytical Signal ◽  
Veterinary Drugs ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Optimal Conditions ◽  
Sodium Metabisulphite ◽  
Active Substances

An analytical method for the quantitative determination of antioxidant sodium metabisulphite in veterinary drugs has been proposed by spectrophotometric method. Based on the literature data, the optimal conditions of the analytical reaction were selected experimentally. The dependence of the value of the analytical signal on the temperature of the reaction medium, concentration of p-rosaniline and duration of the reaction was investigated to establish the optimal conditions of the analytical reaction and obtain a stable analytical signal. The stability of the colored analytical form in time was also checked and the linear dependence of the value of the analytical signal on the concentration of sodium metabisulphite was investigated. The analytical reaction at room temperature is optimal. The maximum analaytical signal is achieved by carrying out the analytical reaction for 10 minutes and then practically does not change for an hour. To achieve the maximum analytical signal, it is necessary to use a 20-fold excess of dye relative to sodium metabisulphite. The analytical signal remains stable only for the first hour, then gradually begins to decrease. Metrological characteristics of the method of determination of metabisulphite in veterinary drugs are calculated, the limits of spectrophotometric determination are 0.33 – 2.50 μg/ml. The correctness of the developed method was checked on model solutions by the method of "introduced-found" method of comparison in the presence of various biologically active substances that are part of drugs together with sodium metabisulphite. The content of sodium metabisulphite in veterinary drugs of domestic and foreign production at different intervals of their storage time was established. It is shown that the content of sodium metabisulphite in drugs decreases during their storage time, until complete disappearance, which directly affects the content of the active substance, because in the absence of antioxidant oxidative processes with biologically active substances begin to take place.

scholarly journals Efficient and Stable Magnetic Chitosan-Lipase B from Candida Antarctica Bioconjugates in the Enzymatic Kinetic Resolution of Racemic Heteroarylethanols

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 350 ◽  
Author(s):  
Cristina Georgiana Spelmezan ◽  
László Csaba Bencze ◽  
Gabriel Katona ◽  
Florin Dan Irimie ◽  
Csaba Paizs ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Vinyl Acetate ◽  
Kinetic Resolution ◽  
Covalent Binding ◽  
Enantiomeric Excess ◽  
Candida Antarctica ◽  
Optimal Conditions ◽  
Lipase B ◽  
Magnetic Chitosan ◽  
Enzymatic Kinetic Resolution

Lipase B from Candida antarctica immobilized by covalent binding on sebacoyl-activated chitosan-coated magnetic nanoparticles proved to be an efficient biocatalyst (49.2–50% conversion in 3–16 h and >96% enantiomeric excess) for the enzymatic kinetic resolution of some racemic heteroarylethanols through transesterification with vinyl acetate. Under optimal conditions (vinyl acetate, n-hexane, 45 °C), the biocatalyst remains active after 10 cycles.

EVIDENCE FOR NON-COVALENT BINDING OF IODOAMINOACIDS IN PURIFIED THYROGLOBULIN

1969 ◽  
Vol 62 (2) ◽  
pp. 210-216
Author(s):  
Urban Rosenqvist ◽  
Sven Almqvist
Keyword(s):  
Covalent Binding ◽  
Gel Filtration ◽  
Two Dimensional ◽  
Covalent Bonds ◽  
Acetone Extracts

ABSTRACT In vivo 125I-labelled dog thyroglobulin was either extracted with acid acetone or subjected to gel filtration, in order to see whether the iodoaminoacids could be removed. The acetone extracts or the material adsorbed on to the Sephadex columns contained 5–16% of the total 125I-activity present in the purified protein. These fractions of radioactivity were analyzed by two dimensional chromatography and iodoaminoacids found to be present. By equilibrium experiments it was further shown that our thyroglobulin preparation would only bind thyroxine but not 3-mono- and 3,5-diiodotyrosine. A possible interpretation of these results is that at least a fraction of the iodinated compounds of thyroglobulin is linked to the protein by non-covalent bonds.

Freeze-extrusion for controllable assembly of 3-dimensional ultra-fine and amorphous fibrous matrices: potential applications in sorption

2018 ◽  
Vol 6 (22) ◽  
pp. 10320-10330 ◽  
Author(s):  
Bingnan Mu ◽  
Wei Li ◽  
Helan Xu ◽  
Lan Xu ◽  
Yiqi Yang
Keyword(s):  
Mechanical Properties ◽  
3 Dimensional ◽  
Sorption Ability ◽  
Potential Applications ◽  
High Sorption ◽  
Fibrous Matrices

High amorphousness, large porosity and good mechanical properties endow fibrous matrices with high sorption ability and reusability.

scholarly journals Haptenation: Chemical Reactivity and Protein Binding

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Itai Chipinda ◽  
Justin M. Hettick ◽  
Paul D. Siegel
Keyword(s):  
Protein Binding ◽  
Specific Binding ◽  
Chemical Reactivity ◽  
Covalent Binding ◽  
Kinetic Studies ◽  
Low Molecular Weight ◽  
Covalent Bonds ◽  
Protein Binding Sites ◽  
Disulfide Exchange ◽  
Histocompatibility Complex

Low molecular weight chemical (LMW) allergens are commonly referred to as haptens. Haptens must complex with proteins to be recognized by the immune system. The majority of occupationally related haptens are reactive, electrophilic chemicals, or are metabolized to reactive metabolites that form covalent bonds with nucleophilic centers on proteins. Nonelectrophilic protein binding may occur through disulfide exchange, coordinate covalent binding onto metal ions on metalloproteins or of metal allergens, themselves, to the major histocompatibility complex. Recent chemical reactivity kinetic studies suggest that the rate of protein binding is a major determinant of allergenic potency; however, electrophilic strength does not seem to predict the ability of a hapten to skew the response between Th1 and Th2. Modern proteomic mass spectrometry methods that allow detailed delineation of potential differences in protein binding sites may be valuable in predicting if a chemical will stimulate an immediate or delayed hypersensitivity. Chemical aspects related to both reactivity and protein-specific binding are discussed.

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