The polysaccharide content and reducing power of proteins and of their digest products.

THE carbohydrate contents of proteins are of value in differentiating individual serum proteins and in following the course of fractionation processes [Hewitt, 1934-1938]. Apart from these practical considerations, however, the presence of carbohydrate groups or polysaccharides in proteins is of theoretical interest also, from the point of view of the structure of the protein molecule. In order to separate the polysaccharide completely from protein material very drastic chemical treatment is necessary [Levene & Mori, 1929; Rimington, 1931; Bierry, 1934; Onoe, 1936]. Whilst this may be taken as evidence that the polysaccharide forms an integral part of the protein molecule, it also raises doubts whether the constitution of the polysaccharide present in the protein molecule is necessarily the same as that of the isolated material, particularly when the yield of purified polysaccharide is very low. Any data obtainable without previous isolation of the polysaccharide are therefore of interest, so it was decided to attempt to correlate the reducing powers of various proteins with their polysaccharide contents. Below are presented data on the carbohydrate contents, glucosamine contents and reducing powers of various proteins, and of the effect of various hydrolytic and enzymic digestion processes.