No abstract

No abstract

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 × 10 8 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 ( K m ) 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.

No abstract

Graphical abstract

No abstract

Affinity haemoadsorbents based on WY, WTY, WNY ligands and polysaccharide matrix were developed for the human immunoglobulin G binding. The characteristics of new sorbents such as the binding of total IgG and binding of IgG subclasses were compared. It was found that all new sorbents well extract the IgG from the blood plasma. It was evidenced that WNY-based sorbent is more effective for binding of IgG subclass 3. The determination of physic-chemical characteristics of IgG binding revealed that desorption constants for IgG are 10 ± 3, 28 ± 4 and 13 ± 3 µM for WY, WTY, WNY based sorbents respectively. Maximum sorption capacities for IgG are 43 ± 2, 45 ± 3 and 46 ± 3 mg IgG per ml of sorbent for WY, WTY, WNY based sorbents respectively. Also it was shown that the new sorbents are compatible with blood and are suitable for the medical purposes.

The bacteriolytic activity of interleukin-2 and chicken egg lysozyme in the presence of various substances has been studied. Glycine and lysine do not affect the activity of interleukin-2 but increase that of lysozyme, showing a bell-shape concentration dependence peaking at 1.5 mM glycine and 18 mM lysine. Arginine and glutamate activate both interleukin-2 and lysozyme with a concentration dependence of the saturation type. Aromatic amino acids have almost no effect on the activity of both interleukin-2 and lysozyme. Aromatic amines, tryptamine, and tyramine activate interleukin-2 but inhibit lysozyme. Peptide antibiotics affect interleukin and lysozyme similarly and exhibit maximum activity in the micromolar range of antibiotics. Taurine has no effect on the activity of interleukin-2 and lysozyme. Mildronate showed no influence on lysozyme, but it activated interleukin-2 with the activity maximum at 3 mM. EDTA activates both interleukin-2 and lysozyme at concentrations above 0.15 mM.