Kinetics of casein hydrolysis by peptidase from Bacillus thuringiensis var. israelensis

The kinetics of enzyme reaction is generally studied using the Michaelis-Menten equation and various methods of its linearization. Each method has its advantages and drawbacks, so their comparison for determining the kinetics of new enzymes action is topical. The aim of this work was to study the kinetics of casein hydrolysis catalyzed by new peptidase from Bacillus thuringiensis var. israelensis IMB B-7465 using several methods of enzyme activity assessment and Michaelis-Menten equation linearization. The satisfactory agreement between kinetic constants values obtained by the methods of Lineweaver-Burk, Hanes, Eadie-Hofstee, Cornish-Bowden-Eisenthal was established. The Lineweaver-Burk method was shown to be optimal for determining Km and Vmax of casein hydrolysis. Estimation of caseinolytic activity with the use of ortho-phthalic dialdehyde allowed more accurate Vmax determination compared to the use of Anson and Kunitz methods

The influence of coordinative tartrate and malatogermanate compounds on the activity of α-L-rhamnosidase preparations from Penicillium tardum, Eupenicillium erubescens and Cryptococcus albidus

Recently enzyme preparations of microbial origin become increasingly important in different industries. Preparations of α-L-rhamnosidase are used in the pharmaceutical industry as well as in scientific work as a tool for analytical research. We have obtained purified α-L-rhamnosidase preparations from Penicillium tardum, Eupenicillium erubescens and Cryptococcus albidus microorganism strains which are effective enzyme producers. The aim of the study was to estimate the ability of germanium coordination compounds to enhance enzyme catalytic activity. The effects of 11 heterometal mixed ligand tartrate (malate-)germanate compounds at 0.01 and 0.1% concentration on the activity of α-L-rhamnosidase preparations from Penicillium tardum IMV F-100074, Eupenicillium erubescens and Cryptococcus albidus 1001 were studied at 0.5 and 24 h exposition. The inhibitory effect of [Ni(bipy)3]4[{Ge2(OH)2(Tart)2}3Cl2]·15H2 on P. tardum α-L-rhamnosidase was revealed. All studied compounds except [CuCl(phen)2][Ge(OH)(HMal)2] were shown to increase activity of P. tardum α-L-rhamnosidase at a longer term of exposition. Activity of E. erubescens α-L-rhamnosidase was shown to be stimulated by d-metal cation-free compounds. C. albidus α-L-rhamnosidase occurred to be insensitive to all compounds studied

Novel monoclonal antibody to fibrin(ogen) αC-region for detection of the earliest forms of soluble fibrin

Obtaining new monoclonal antibodies (mAbs) towards fibrin(ogen) and its fragments is an important task for studying mechanisms of blood clot formation, searching for novel antithrombotic agents and developing immunodiagnostics. The aim of the present work was to create and characterize a new mAb towards the fibrin(ogen) αС-region. We surmise that having a specific mAb towards this flexible part of the molecule will allow us to study the role of the αС-region in fibrin polymerization and also to develop an approach for detecting the earliest forms of soluble fibrin by sandwich ELISA. Using hybridoma technology we оbtained mAb 1-5A to the αC-region of fibrinogen.. It was characterized using several variations of ELISA and Western blot. Application of specific proteases together with MALDI-TOF analysis allowed us to localize its epitope that is located in fragment 537-595 of the Aα-chain of fibrin(ogen). МAb 1-5A can be used as a detecting tag-antibody in sandwich ELISA for the quantification of the earliest forms of soluble fibrin which are uncleaved by plasmin and preserved C-terminal portions of αC-regions. These earliest forms of soluble fibrin are direct evidence of blood coagulation system activation, thrombin generation and the danger of intravascular thrombus formation. Their determination will provide additional, more accurate information about the state of the blood coagulation system and the risk of blood clotting, which is very important for the timely and correct selection of adequate antithrombotic therapy. MAb 1-5A effectively binds the αC-containing molecules of fibrinogen and fibrin in blood plasma. It also can be used for studying protein-protein and protein-cellular interactions of the αC-regions of fibrin(ogen)

Ceramic Water Filter for Point-Of-Use Water Treatment in Developing Countries: Principles, Challenges and Opportunities

Drinking water source contamination poses a great threat to human health in developing countries. Point-of-use (POU) water treatment techniques, which improve drinking water quality at the household level, offer an affordable and convenient way to obtain safe drinking water and thus can reduce the outbreaks of waterborne diseases. Ceramic water filters (CWFs), fabricated from locally sourced materials and manufactured by local labor, are one of the most socially acceptable POU water treatment technologies because of their effectiveness, low-cost and ease of use. This review concisely summarizes the critical factors that influence the performance of CWFs, including (1) CWF manufacturing process (raw material selection, firing process, silver impregnation), and (2) source water quality. Then, an in-depth discussion is presented with emphasis on key research efforts to address two major challenges of conventional CWFs, including (1) simultaneous increase of filter flow rate and bacterial removal efficiency, and (2) removal of various concerning pollutants, such as viruses and metal(loid)s. To promote the application of CWFs, future research directions can focus on: (1) investigation of pore size distribution and pore structure to achieve higher flow rates and effective pathogen removal by elucidating pathogen transport in porous ceramic and adjusting manufacture parameters; and (2) exploration of new surface modification approaches with enhanced interaction between a variety of contaminants and ceramic surfaces

Stability of native and modified α-galactosidase of Cladosporium cladosporioides

By modifying carbohydrate component of glycoproteins it is possible to elucidate its role in manifestation of structural and functional properties of the enzyme. The comparison of activity and stability of the native and modified by oxidation with sodium periodate α-galactosidase of Cladosporium cladosporioides was carried out. To determine α-galactosidase activity the authors used n-nitrophenyl synthetic substrate, as well as melibiose, raffinose and stachyose. Modification of the carbohydrate component had a significant effect on catalytic properties of the enzyme. Both the reduction of Vmax and enzyme affinity for natural and synthetic substrates were observed. The native enzyme retained more than 50% of the maximum activity in the range of 20-60 °C, while for the modified enzyme under the same conditions that temperature range was 30-50 °C. The modified α-galactosidase demonstrated a higher thermal stability under neutral pH conditions. The residual activity of the modified α-galactosidase was about 30% when treated with 70% (v/v) methanol, ethanol and propanol. About 50% of initial activity was observed when 40% ethanol and propanol, and 50% methanol were used. It was shown that the modification of C. cladosporioides α-galactosidase by sodium periodate is accompanied by a significant decrease in enzyme activity and stability, probably caused by topological changes in the tertiary and quaternary structure of the protein molecule

α-Galactosidase of Aspergillus niger: purification and properties

Highly purified α-galactosidase (specific activiys 25 U/mg protein) has been isolated from the cultural liquid of Aspergillus niger. The enzyme is thermo- and pH-stable, with pH-optimum 4.1, and temperature optimum 60 °C. Km and Vmax for nitrophenyl substrate was shown to be 1.19 mM and 25 µmol/min/mg protein, respectively. α-Galactosidase was inhibited by the product of reaction D-galactose (Ki – 6.2 × 10-2M). The enzyme displayed narrow specificity towards glycon. It proved to be metal-independent. The active center of the enzyme contains the carboxylic group of the C-terminal aminoacid and imidazole group of histidine

Influence of chemical reagents and UV irradiation on the activity of Penicillium canescens α-galactosidase

Investigations of the influence of chemical and physical factors on the conformational and functional properties of enzymes make a significant contribution to the study of the mechanism of action of industrially important proteins. The aim of the work was to evaluate the effect of chemical reagents and UV irradiation on the catalytic properties of Penicillium canescens α-galactosidase. Enzyme activity was assessed with p-nitrophenyl-α-D-galactopyranoside. Studies of the functionally active glycosidase groups were carried out on the basis of inhibitory and kinetic analysis using Dixon and Luinuiver-Burke methods with help of specific chemical reagents. A significant decrease in the activity of α-galactosidase in the presence of carbodiimi­des, diethylpyrocarbonate, the reagents on sulfhydryl groups was shown. A UV-induced decrease in enzyme activi­ty in the dose range of 900-7200 J/m2 was noted. Based on the data obtained, the imidazole group of histidine, carboxyl groups of C-terminal amino acids and the SH-groups of cysteine are assumed to play an important role in the manifestation of the activity of P. canescens α-galactosidase

KERATINOLYTIC ENZYMES: PRODUCERS, PHYSICAL AND CHEMICAL PROPERTIES. APPLICATION FOR BIOTECHNOLOGY

The aim of the review was to analyze the current ideas on keratinases, a group of proteolytic enzymes that catalyse the cleavage of keratins, which are highly stable fibrous proteins. Representatives of various taxonomic groups of microorganisms, including fungi, actinomycetes and bacteria, are keratinase producers. Modern classification of keratinases according to the MEROPS database is given. The studies of physical and chemical properties of keratinases indicate that the enzymes are active in a wide range of temperature and pH values, with the optimal action at neutral and alkaline pH and t = 40–70 oC. It was shown that microbial keratinases were predominantly the metallo-, serine- or metallo-serine proteases. They are usually extracellular, and their synthesis is induced by keratin substrates. The review discusses the practical use of keratinases. These enzymes have been successfully applied in bioconversion of keratin wastes to animal feed and nitrogenous fertilizer, as well as in leather, textile, detergent, cosmetic, pharmaceutical industries. Keratinases are also applicable as pesticides and in the production of nanoparticles, biofuel, biodegradable films, glues and foils. In addition, keratinases are used in the degradation of prion proteins which are able to cause a number of human and animal neurodegenerative diseases of spongiform encephalopathy

ANTIVIRAL ACTIVITY OF LIPOPOLYSACCHARIDES OF Pseudomonas chlororaphis subsp. aureofaciens

The aim of the study was to investigate the ability of lipopolysaccharides of two strains of Pseudomonas chlororaphis subsp. aureofaciens to inhibit in vitro the reproduction of human viruses: influenza A/FM/1/47 (H1N1), herpes simplex type 2 and bovine diarrhea, which is used as a model of hepatitis C virus, as well as to suppress hepatitis C virus production in model system of cells transfected with cDNA of this virus. It has been established that for both lipopolysaccharides in three types of cultures (MDCK, Vero and MDBK) the toxicity is not manifested even in a concentration of 100.0 μg/ml, and decreasing in infectious virus titer more than by 2.0 lg TCD50 (ED99) was already achieved at concentrations of 1.55 mg/ml. Selectivity indexes determination of lipopolysaccharides preparations against the influenza A/FM/1/47 (H1N1) virus, herpes simplex virus type 2 and bovine diarrhea virus shows that lipopolysaccharides of P. chlororaphis subsp. aureofaciens UCM B-306 and UCM B-111 are effective inhibitors of investigated viruses reproduction: selectivity index is at least 64. In the model of Jurkat cells transfected with human hepatitis C virus cDNA, viral RNA loading was determined in cells treated with lipopolysaccharides of P. chlororaphis subsp. aureofaciens. The results of the studies indicate that when lipopolysaccharides of both strains are administered, the production of the hepatitis C virus is completely inhibited