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PubMed1955

Sedimentation and viscosity studies on the capsular and somatic polysaccharides of pneumococcus Type III.

Sedimentation constants at infinite dilution have been found to be 1.89 and 4.06 for the somatic and capsular polysaccharides, respectively, from pneumococcus Type III. Intrinsic viscosities have been determined for the somatic and capsular polysaccharides of pneumococcus Type III using the Ostwald viscometer. Molecular weights and dimensions have been calculated for the somatic and capsular polysaccharides of pneumococcus Type III assuming the molecules to be prolate ellipsoids of revolution. Values for the somatic polysaccharide are: molecular weight, 26,400; diameter, 0.97 mmicro; and length, 36.18 mmicro. Values for the capsular polysaccharide are: molecular weight, 171,800; diameter, 1.04 mmicro; and length, 177.87 mmicro. The molecular weights were calculated for the somatic and capsular polysaccharides of pneumococcus Type III assuming the molecules to be flexible chains. The value of the molecular weight of the somatic polysaccharide is 31,500 and the value for the molecular weight of the capsular polysaccharide is 267,500. The molecules of both the somatic and capsular polysaccharides exhibit high degrees of asymmetry.

Polysaccharides↗
PubMed1956

The immunological specificity of type II Pneumococcus and its separation into partial specificities.

The specificity of Type II pneumococcus determined by its capsular polysaccharide (S II) may be separated into three partial specificities, each characteristic of one of the three component sugars of S II, namely, glucuronic acid, glucose, and rhamnose. By far the largest portion of antibodies in Type II antipneumococcus horse sera which cross-react with carbohydrates containing one or more of these sugars are reactive with those characterized by multiple groupings of glucuronic acid. This confirms, extends, and explains earlier observations. In confirmation of predictions based upon existing information tamarind seed polysaccharide (jellose), in which much of the glucose exists as 1,4,6-branch points, was found to react in Type II antisera. Several instances are given of cross-reactions in these antisera apparently due to the L-rhamnose component of the reacting polysaccharides. The antisera contain far more antibody capable of precipitating with substances with multiple units of glucuronic acid than with those so far tested containing multiple 1,4,6-branch points of glucose or multiple groupings of rhamnose. The long known increase of titer of gum arabic on partial hydrolysis is now fully explained and discussed, and a chemical picture is given of the change in "avidity." The sum of the partial specificities measured does not equal the whole. Quantitative data illustrating these points are given.

Cross Reactions↗
PubMed1956

Effect of silicate on Gram staining and viability of pneumococci and other bacteria.

Application of silicate solutions to living or heat-killed pneumococci and to certain "viridans" streptococci causes their conversion from a Gram-positive to a Gram-negative state. The original staining properties can be restored by suspending the silicate-treated bacteria in alkaline solutions of various salts but not by simple washing in water. Living pneumococci and the strains of streptococci whose staining properties are similarly affected are killed when suspended in silicate solutions. In other Gram-positive species silicate causes conversion to Gram negativity but restoration to positivity occurs upon washing in water. In a third group of Gram-positive organisms silicate has no effect on the Gram reaction. The viability of organisms in these two groups is unaffected by silicate under the conditions employed. No effect on staining or viability of Gram-negative bacteria has been observed. The effects of silicate on staining and viability are inhibited by nutrient broth or whole serum but not by purified serum albumin. Lecithin, choline, and other substituted ammonium compounds also inhibit the effects of silicate on pneumococci.

Bacteria↗