Lysis of gram-negative bacteria by lysozyme

Lactoferrin, an Iron-Binbing Protein Ni Neutrophilic Leukocytes

“…It has been reported that the lytic activity of lysozyme is raised and extended to several kinds of otherwise insensitive bacteria in the presence of chelating agents (27). Since lactoferrin is a powerful chelator of iron (2, 6, 7) as well as of copper (8), it is tempting to speculate that this protein may be a valuable adjunct of lysozyme in the defense against bacterial invasion.…”

The Lysis of Micro-organisms by Lysozyme and Related Enzymes

“…Thus BrzcceEZa abortus is lysed by lysozyme and appreciable quantities of the substrate can be extracted from the cells (Epstein & Chain, 1940). Unlike the Gram-positive bacteria, the lysozyme sensitivity of intact cells of many Gram-negative organisms can often be established only after the application of special techniques such as the following: (1) the addition of sodium hydroxide solutions after exposure to lysozyme under the conditions described by Nakamura (1923) ; (2) incubation with lysozyme a t low pH values (c. 3.5) at 45" followed by the addition of alkali c. pH 10 (Peterson & Hartsell, 1955; Grula & Hartsell, 1957a, b ) ; (3) prior treatment of bacteria with acetone or heat (Warren, Gray & Bartell, 1955); (4) treatment with lysozyme in the presence of 'Versene' (ethylenediamine tetra-acetic acid-EDTA) as reported by Repaske (1956). Thus with many Gram-negative bacteria, the lysis due to lysozyme is often negligible, but the contribution due to lysozyme when the treatment is combined with any of the above procedures, is frequently quite large.…”

The Bacterial Cytoplasmic Membrane

“…The isolated fragments (so-called 'ghosts ') appear in metal-shadowed specimens to be approximately 500 m p in cross section, about 100 A. thick, and to be free from adhering cell wall and cytoplasm; they nevertheless may contain up to 20% of their dry weight as carbohydrate, the rest being mainly lipoprotein. Fractions rich in lipoprotein but containing various amounts of cell wall may also be prepared by similar methods from spheroplasts prepared by lysozyme treatment in the presence of versene (Repaske, 1956). The action of autocatalytic enzymes (Mitchell & Moyle, 19-56), unbalanced growth produced by the action of penicillin or other antibiotics (Lederberg & St Clair, 1958;McQuillen, 1958) or the omission of an essential cell-wall constituent such as lysine or diaminopimelic acid (McQuillen, 1958) have also been used to prepare spheroplasts from which membrane-enriched fractions may be isolated.…”