A simple and rapid method for testing the quality of fermented beverages is demonstrated, based on the determination of total protein using Coomassie dye and comparison of the absorption spectra of the samples. The applicability of the approach for the analysis of red and white wine, beer, cider and kvass is shown. In addition to accurate instrumental characterization of samples, this approach can be adapted for qualitative testing in the field or at home.

Bacteria appear to be an inevitable element of soil geochemistry because they participate actively in chemical transformations of soil media components. One of the factors determining the composition of bacterial population in soil is resistance of bacteria to enzymes which hydrolyze cell walls. In the following research, resistance of bacteria (Priestia megaterium, Micrococcus luteus and Escherichia coli) to lysozyme in the pH range appropriate for soils is investigated. All the three species are proved to be most sensitive to lysozyme in slightly alkaline conditions (P. megaterium is least resistant at pH 8.0, M. luteus at pH 8.3, E. coli at pH 8.5), and resistance of all the three microorganisms in the range of pH values of 6.0—7.0 changes insignificantly. A possible factor defining the pH optimum for lysozyme activity in relation to these bacteria is the structure of negatively charged components of their cell walls and outer membranes.

This study describes the applicability of the fluorescence polarization assay (FPA) based on the use of FITC-labeled oligosaccharide tracers of defined structure for the measurement of active lysozyme in hen egg white. Depending on the oligosaccharide chain length of the tracer, this method detects both the formation of the enzyme-to-tracer complex (because of lectin-like, i.e., carbohydrate-binding action of lysozyme) and tracer splitting (because of chitinase activity of lysozyme). Evaluation of the fluorescence polarization dynamics enables simultaneous measurement of the chitinase and lectin activities of lysozyme, which is crucial for its detection in complex biological systems. Hen egg white lysozyme (HEWL), unlike human lysozyme (HL), formed a stable complex with the chitotriose tracer that underwent no further transformations. This fact allows for easy measurement of the carbohydrate-binding activity of the HEWL. The results of the lysozyme activity measurement for hen egg samples obtained through the FPA correlated with the results obtained using the traditional turbidimetry method. The FPA does not have the drawbacks of turbidimetry, which are associated with the need to use bacterial cells that cannot be precisely standardized. Additionally, FPA offers advantages such as rapid analysis, the use of compact equipment, and standardized reagents. Therefore, the new express technique for measuring the lysozyme activity is applicable for evaluating the complex biomaterial, including for the purposes of food product quality control.

It was found that glycine, glutamate, lysine, histidine, and arginine increase the rate of Escherichia coli cell lysis by chicken egg lysozyme. The highest cell lysis rates (lysis acceleration by 7.0-8.5 times) are provided by combinations of the following amino acids: 1) arginine, histidine, and lysine, 2) glutamate, histidine, and arginine, 3) glycine, lysine, and arginine (all charged amino acids are applied in concentrations of 5 mM, the concentration of glycine is 1.5 mM). These amino acids added into food products with lysozyme as a preservative can significantly increase antibacterial properties of the latter. This could help increase the shelf life of human food and also serve as a preventive measure against the spread of bacterial infections among farm animals.

In this study, an attempt is made to analyze the published data regarding the effectors of bacterial lysis in the presence of various bacteriolytic enzymes. Despite the differences between such enzymes, it is possible to identify certain general patterns of their action on a highly complex substrate—a living bacterial cell protected by a cell wall and additional complexes of biopolymers associated with it. Chicken and human lysozymes are the best known of these enzymes. They have some structural differences but are generally very similar in properties. Understanding the characteristics of the antibacterial action of bacteriolytic enzymes present both in medications and in the human immune system is extremely important for the development of new approaches to combat bacterial infections, including antibiotic-resistant ones. Moreover, certain logical and methodological approaches used to study bacteriolytic enzymes can be extremely useful for studying and describing other enzymes that affect complex polymer substrates in real biological situations.

New information about lysozyme. Activation of lysozyme by arginine, histidine, glutamate. Helps the immune system fight bacterial infection.

The current study focussed on the regulation of the bacteriolytic activity of lysozyme with regard to the bacterial cells of Escherichia coli and the influence on it by the presence of various combinations of charged amino acids and glycine. The effects of combinations of the aforementioned amino acids on the activity of lysozyme had not been previously investigated. The effect of enhancing enzyme antibacterial activity in the presence of effectors was compared in the lysozymes of humans (HL) and those of chickens (CL), taking into account the influence of ionic strength and pH. It was discovered that the use of double and triple combinations of amino acids could lead to significantly greater activation of lysozyme than was previously possible using single effectors. A particularly significant increase in bacteriolytic activity was observed when using a buffer solution with low ionic strength (5-10 mM). An increase in lysozyme activity of approximately 10 times was attained under the simultaneous presence of glutamate, histidine, and arginine for the human enzyme and with the simultaneous presence of lysine, histidine, and arginine for that found in chickens (5 mM of each amino acid).

E. coli strains are created as producers of recombinant β1-adrenoreceptor epitopes as part of chimeric proteins. The corresponding epitope sequences are located in the C-terminal region of the human heart fatty acid binding protein (hH-FABP) and separated from it by the linker sequence (Gly4Ser)3. A solid-phase enzyme-linked immunosorbent assay (ELISA) to detect autoantibodies against the β1-adrenergic receptor in human blood serum based on a recombinant epitope is developed. Blood sera of patients (N = 76) with various diagnoses of cardiopathologies and other diseases are analyzed. A significantly high level of autoantibodies to the β1-adrenergic receptor is detected in some patients with a confirmed diagnosis of cardiovascular diseases, in most cases those with a diagnosis of acute myocardial infarction.

For human and chicken lysozyme, the relationship between changes in the parameters of enzyme adsorption on living Escherichia coli bacterial cells and the value of its effective bacteriolytic activity in the presence of glycine and charged amino acids is studied. It is shown for both human and chicken lysozyme that free amino acids added to a concentration of 1.5 mM for glycine or 5.0 mM for glutamate, aspartate, histidine, arginine, and lysine reduce the desorption constant of the enzyme on bacterial cells by factors of 1.4 to 2.0. At the same time, an increase in the bacteriolytic activity of lysozyme by factors of 1.5 to 1.9 is also observed. Thus, the enhancement of antibacterial activity in the presence of glycine and charged amino acids can be explained by the improvement in the productive sorption of the enzyme on the substrate of the bacterial cells.

A deviation of the dependence of the lysis rate of Micrococcus luteus cells from the Michaelis-Menten kinetics after lysozyme incubation with pluronic P123 for 2 days was observed by the study of the interaction of pluronic P123 and hen egg-white lysozyme (HEWL). The observed deviation is presumably induced by the formation of two complexes differed in catalytic properties in the system, depending on the cell concentration. The ratio of the formed complexes is determined by the substrate concentration. The interaction with the pluronic changes the catalytic properties of HEWL. An increase in the cell concentration results probably in the simultaneous binding of HEWL with the substrate and pluronic, inducing structural changes in the active site of the enzyme and changes in the bacteriolytic activity.

The general characteristics of the effect of surfactants on the activity of lysozyme were demonstrated. The kinetics of bacterial cell lysis is consistent with the Michaelis-Menten equation and the presence of surfactants does not shift the pH-optimum of activity. Surfactants do not change the Km value but instead, affect the Vmax value. The experimental dependencies are well described by theoretical equations, which assume three surfactant binding sites on the lysozyme molecule. The dependencies of the activity of lysozyme on the surfactant concentration are either a step type (i.e., a higher plateau becomes a lower plateau), or a dependency with a maximum and continuation of the curve in the form of a plateau but with an increase in the surfactant concentration. It can be assumed that there is a mechanism for the regulation of lysozyme activity by an unknown natural factor that has a suitable hydrophobic radical capable of binding to the surface of lysozyme.

Elevated levels of apoB-100 containing lipoproteins and markers of systemic inflammation are often observed in patients with cardiovascular diseases. The concentrations can be reduced by pharmacotherapy or extracorporeal treatment. The sorbent, which removes CRP and atherogenic lipoproteins, simultaneously reduces the bloodstream concentration of these components. The efficacy and selectivity of the designed sorbent were studied, desorption constants of CRP (Kd = 4.2 × 10-8 M) and LDL (Kd = 7.7 × 10-7 M) were distribution coefficients of CRP (Kc = 101) and Lp(a) (Kc = 38) were calculated, and the ability to bind large amounts of atherogenic lipoproteins (up to 32 mg of TC per mL of the sorbent gel) was demonstrated. Our sorbent can be recommended for performing complex removal of CRP and atherogenic lipoproteins from the blood plasma in patients with refractory hyperlipidemia and CVD that are accompanied by elevated levels of CRP.

The influence of nonionic surfactants on the bacteriolytic activity of lysozyme is studied on the model cells of Micrococcus luteus using Pluronics P123, L121, and F127, as well as Brij-35. These compounds form complexes with lysozyme through hydrogen-bonding interactions between the ethylene oxide fragments of surfactant and the amino acids residues of lysozyme surface. The bacteriolytic activity of lysozyme decreases in the order of F127 < P123 < L121 ≈ Brij-35, probably because of the steric hindrances of the protein’s interaction with the cells’ substrate.

— Different methods of covalent lysozyme immobilization have been compared to choose an optimal approach to the development of a material suitable for medical applications in extracorporeal therapy. A novel method for lysozyme immobilization on a polymeric agarose matrix has been proposed, which provides the effective action of lysozyme on bacterial cells and eliminates the leakage of the enzyme from the material. The resultant immobilized lysozyme exhibits bacteriolytic activity toward Gram-positive bacteria Micrococcus luteus and Gram-negative bacteria Escherichia coli . During the immobilization of the enzyme, a broadening of the pH optimum of its activity occurs. The compatibility of immobilized lysozyme with human whole blood has been shown.

•Chemical modification with benzaldehyde and anisaldehyde affects only 1–2 amino groups of lysozyme molecule.•Chemical modification does not prevent further covalent immobilization of the protein using the remaining free amino groups.•Composite material based on modified covalently immobilized lysozyme shows excellent endotoxin adsorption.•The adsorption of IgG on immobilized lysozyme did not increase after chemical modification.•The ability to specifically bind to IgG may be associated with the opsonin function of lysozyme.

The emergence of new antibiotic‐resistant bacterial strains means it is increasingly important to find alternatives to traditional antibiotics, such as bacteriolytic enzymes. The bacteriolytic enzyme lysozyme is widely used in medicine as an antimicrobial agent, and covalent immobilization of lysozyme can expand its range of possible applications. However, information on the effect of such immobilized preparations on whole bacterial cells is quite limited. Here, we demonstrate the differential effects of glycine and charged (basic and acidic) amino acids on the enzymatic lysis of Gram‐positive and Gram‐negative bacteria by soluble and immobilized lysozyme. Glycine and basic amino acids (histidine, lysine, and arginine) significantly increase the rate of lysis of Gram‐negative Escherichia coli cells in the presence of soluble lysozyme, but they do not substantially affect the rate of enzymatic lysis of Gram‐positive Micrococcus luteus. Glutamate and aspartate significantly enhance enzymatic lysis of both E. coli and M. luteus. When using immobilized lysozyme, the effects of amino acids on the rate of cell lysis are significantly reduced. For immobilized lysozyme, the presence of an external diffusion mode on cell lysis kinetics at bacterial concentrations below 4 × 108 colony‐forming units·mL−1 was shown. The broadening of the pH optimum of lysozyme activity after immobilization has been demonstrated for both Gram‐positive and Gram‐negative bacteria. The Michaelis constant (Km) values of immobilized lysozyme were increased by 1.5‐fold for E. coli cell lysis and 4.6‐fold for M. luteus cell lysis compared to soluble enzyme. A greater understanding of the effect of amino acids on the activity of native and immobilized lysozyme is important for both the development of new materials for medical purposes and elucidating the interaction of lysozyme with bacterial cells. Of particular interest is our finding that lysozyme activity against Gram‐negative bacteria is enhanced in the presence of glycine and charged amino acids over a wide range of concentrations.