Lysozyme is an enzyme found in leukocytes, egg white, skin, mucous membranes, and certain body fluids (saliva, tears). Lysozyme breaks down the mucopolysaccharides that make up the structural basis of the bacterial cell wall, thereby causing lysis of the bacteria. Lysozyme protects the mucous membranes of the eye, mouth, intestines and nasopharynx from infection.
Lysozyme (muramidase) is an enzyme that has a specific ability to cause the dissolution of certain microorganisms. Fleming (A. Fleming) united bacteriolytic proteinaceous substances of different origin in the group of "lysozymes".
In humans, lysozyme is found in tears, sputum, saliva, blood serum and plasma, in human milk, in the nasal mucosa, spleen, liver, bone marrow, cartilage, omentum, leukocytes, heart, and intestinal extracts and pancreas. Lysozyme is found in plants (horseradish, radish, turnip, cabbage, primrose), some bacteria and viruses (bacteriophages). Macrophage lysozyme is involved in the intracellular digestion of microbes. The content of lysozyme in animal and plant objects varies widely. Its highest concentration is found in the egg white, horseradish and tears. Enzyme isolation is based on its ability to adsorb to bentonite clay, followed by elution with acidified pyridine (pH = 5.0).
Lysozyme from various sources obtained in crystalline form. Its physicochemical properties and lytic activity vary widely. Mol the mass of animal lysozyme is 14,800, from plants - 24,000, from bacteriophage - 13,900. Lysozyme is one polypeptide chain, consisting of 130-150 amino acid residues; does not contain sulfhydryl groups; resistant to heat up to 100 ° in an acidic environment.
Lysozyme activity is determined by the degree of lysis of a highly sensitive micrococcus (Micrococcus lysodeikticus). Gram-positive microbes are sensitive to lysozyme, gram-negative ones are resistant. The mechanism of action of lysozyme is reduced to the enzymatic cleavage of the rigid murein layer of the bacterial cell wall, which is accompanied by the release of muramine, diaminopimelic, glutamic and aspartic acids, glucosamine, alanine, serine and lysine. As a result, the cell takes the form of a sphere (protoplast) and preserves it in a hypertonic medium, and is torn apart in isotropic or hypotonic (see Bacteriolysis). Thus, with the help of lysozyme, important information was obtained about the anatomy of a bacterial cell. Lysozyme is used in the food industry for canning (for example, caviar). See also Enzymes.