The Soluble Specific Substance of Pneumococcus. v. on the Chemical Nature of the Aldobionic Acid from the Specific Polysaccharide of Type Iii Pneumococcus

The so called soluble specific substances of the three fixed types of Pneumococcus appear identical with three chemically distinct, serologically type specific polysaccharides produced by these organisms during growth in culture media (1). The immunological significance and the chemical nature of these bacterial carbohydrates have been discussed in detail in earlier publications from this laboratory. The present communication deals with the chemical nature of an aldobionic acid, the fundamental building stone of the polysaccharide derived from Type III pneumococcus. This aldobionic acid, the product of hydrolysis of the Type III specific carbohydrate, has been shown (2) to have the formula CIIHrsOloCOOH and to be built up from a hexose (glucose) and a hexose-uranic acid of unknown nature, in such a manner that the carboxyl group and one aldehydic group remain free. It is of interest to extend the investigation of this substance, for it not only appears unique in the field of sugar chemistry, but important in that it or its isomers are found among the hydrolytic products of specific carbohydrates from other microorganisms. The present report aims to identify the hexose-uranic acid which forms half of the molecule of the aldobionic acid, and to explain the nature of the glucosidic linkage which binds the sugar to the acid.