REVERSIBLE INACTIVATION OF AN ENDOTOXIN BY INTRACELLULAR PROTEIN

ENHANCEMENTS OF ANTIBIOTIC ACTIVITY OF COLICINE K AND ALTERATION OF SEROLOGICAL PROPERTIES OF COLICINE K AND ENDOTOXINS

Hemoglobin, its chains, and myoglobin enhance the antibiotic activity of colicine K. These proteins also interact with colicine K and other O antigens to alter their serological activity. The hemoglobin proteins did not alter the serological activities of three Pneumococcus polysaccharides or T4 bacteriophage DNA antigens but did alter the antigenic activity of fetuin. Interaction of hemoglobin and colicine K resulted in a retardation of colicine K antibiotic moiety as measured by gel filtration but did not affect the gel filtration properties of the lipopolysaccharide moiety.

Characteristics of Endotoxin-Altering Fractions Derived from Normal Serum III. Isolation and Properties of Horse Serum α 2 -Macroglobulin

The endotoxin-altering activity of fractions isolated from normal horse serum was examined by incubation of Salmonella typhosa strain 0-901 endotoxin (Boivin) in a solution of the fraction, and subsequent quantitation of any diminution in the capacity of endotoxin to be precipitated by specific anti-endotoxin antiserum. The horse serum fraction isolated by precipitation with ammonium sulfate at a concentration between 1.6 and 2.7 m was incubated with Pronase PA and then with trypsin. When this partly digested fraction was passed twice through a Sephadex G-200 column and eluted with 0.2 m tris(hydroxymethyl)aminomethane buffer, most of the endotoxinaltering activity was found in the first protein peak designated F-1a. F-1a was found to be homogeneous and corresponded to an α 2 -macroglobulin by the techniques of electrophoresis, immunodiffusion, and ultracentrifugation. Approximately 100-fold more F-1a than endotoxin was needed to reduce the antigenicity of the endotoxin by one-half. Alteration was increased when F-1a was incubated with the endotoxin at acid p H or at 45 C rather than at 37 C and was lost after heating F-1a at 56 C for 30 min. N -ethylmaleimide increased the endotoxin-altering activity of horse serum, F-1a, and human plasma fraction III 0 , whereas p -chloromercuribenzoate did not. On the other hand, diazonium-1-H-tetrazole, iodoacetic acid, and benzylchloride suppressed the activity of F-1a. When the interaction of endotoxin and F-1a was examined by immunodiffusion techniques, depolymerization of the endotoxin molecule was indicated. The endotoxin-altering factor of horse serum is discussed in relation to the mechanisms of other known reagents, such as deoxycholate and sodium lauryl sulfate.

Alteration and restoration of endotoxin activity after complexing with plasma proteins

Rudbach, Jon A. (The University of Michigan, Ann Arbor), and Arthur G. Johnson. Alteration of endotoxin activity after complexing with plasma proteins. J. Bacteriol. 92:892-898. 1966.-A substantial decrease in the ability of endotoxin to be precipitated by homologous antiserum and to cause fever occurred after incubation with human plasma or human plasma, Cohn fraction IV-1. The endotoxin, thus altered, also displayed decreased lethality for rabbits. These alterations in endotoxin activity could be restored when the endotoxin-plasma protein mixture was treated with a proteolytic enzyme, and the endotoxin was precipitated with ethyl alcohol. Inactivation of the antigenic and toxigenic properties of the endotoxin molecule by plasma is discussed as resulting from complexing with plasma proteins rather than from enzymatic degradation.

Turbidimetric Changes Accompanying the Interaction of Endotoxin and the α Chains of Human Hemoglobin

Setlow, Peter (Brandeis University, Waltham, Mass.), Lawrence Levine, and Helen Van Vunakis . Turbidimetric changes accompanying the interaction of endotoxin and the α chains of human hemoglobin. J. Bacteriol. 89: 1237–1243. 1965.—With the use of a turbidimetric assay, the effects of p H, ionic strength, anions and cations, and varying concentrations of reactants on the interaction of Escherichia coli endotoxin (prepared by the Boivin procedure) with the α chain of hemoglobin were studied. The reaction was found to be partially reversible by addition of NaCl or by addition of an excess of either reactant. The characteristics of the reaction indicated that complex formation between two multivalent molecules had taken place. The formation of the complex was inhibited by endotoxin (prepared by the Westphal procedure) and by the products which resulted from partial tryptic digestion of α chain.