Immunostimulating and protective effects of terrilytin preparations in staphylococcal infection

In mice infected with staphylococci there was observed less pronounced development of the immune response to sheep red blood cells (SRBC) than in intact animals subjected only to immunization. Administration of free terrilytin to the infected mice increased the immune response development induced by SRBC while the use of immobilized terrilytin normalized it. The supernatant liquid of the spleen cells (SLSC) from the mice treated with the free of immobilized terrilytins stimulated development of the immune response to SRBC in the infected animals and inhibited the function of the suppressor cells in the spleen. The immunomodulating and protective effects of the SLSC fractions isolated with column chromatography on Sephadex G-150 were investigated. Substances of the low molecular fraction of the SLSC proteins (molecular weight of 10-15 kD) from the mice treated with the terrilytins showed immunostimulating and protective properties. The factors inducing both the activity types included peptides and the ribonucleotide component playing a significant role in realization of the immunostimulating and protective effects of the free and immobilized proteases.     

Purification and properties of staphylococcal beta hemolysin. II. Purification of beta hemolysin

Staphylococcal beta hemolysin from the 681 strain of Staphylococcus aureus grown in a Heart Infusion dialysate semisolid medium under 10% carbon dioxide was obtained in an immunoelectrophoretically pure form by a combination of procedures of precipitation with 2 volumes of acetone followed by chromatography on diethylaminoethyl cellulose at pH 6.0. The acetone precipitation procedure did not show any deleterious effect on the hemolytic activity of the beta hemolysin unless the precipitate was left in contact with the acetone for at least 4 hr. The crude preparations contained two types of beta hemolysin. One of these represented the major portion of the total activity of beta hemolysin and behaved as a cation. The other represented a minor (1/5,000) portion of the total beta hemolysin activity and behaved as an anion. These active principles were designated as cationic and anionic beta hemolysins, respectively. An unexpected increase in the total beta hemolysin activity of the crude preparations was noted when these were concentrated by dialysis against polyethylene glycol (20 m). This effect was probably due to polyethylene glycol. A further unexpected increase in the titer of the acetone-precipitated preparations occurred when these were lyophilized. The reason for this incremental increase is not known. It may be due to fragmentation of the beta hemolysin.     

Acid induced unfolding of anthrax protective antigen

Acidic pH plays an important role in the membrane insertion of protective antigen (PA) of anthrax toxin leading to the translocation of the catalytic moieties. The structural transitions occurring in PA as a consequence of change in pH were investigated by fluorescence and circular dichroism measurements. Our studies revealed the presence of two intermediates on-pathway of acid induced unfolding; one at pH 2.0 and other at pH 4-5. Intrinsic fluorescence measurements of these intermediates showed a red shift in the wavelength of emission maximum with a concomitant decrease in fluorescence intensity, indicative of the exposure of tryptophan residues to the bulk solvent. Furthermore, no significant change was seen in the secondary structure of PA at a pH of 2.0, as indicated by far UV-CD spectra. The low pH intermediate of PA was characterized using the hydrophobic dye, 8-anilino-1-naphthalenesulfonate, and was found to have properties similar to those of a molten globule state.