A SPECTROPHOTOMETRIC STUDY OF BLOOD GROUP A-SPECIFIC SUBSTANCE ISOLATED FROM HOG GASTRIC MUCOSA BY GEORGE HOLZMAN * AND CARL NIEMANN

The isolation from hog gastric mucosa of homogeneous preparations of the polysaccharide-amino acid complex possessing the ability to inhibit the isoagglutination of human blood group A cells (1) has been hindered not only by dilliculties of manipulation and the presence in gastric mucosa of substances having properties similar to those of blood group A-specific sub-stance, but also by the fact that direct tests for determining the homo-geneity of the product are often insensitive and unreliable. In the past the efficacy of procedures used for the isolation and purification of group A substance have been evaluated by serological tests and in a few instances by ultracentrifugal analysis (2), electrophoretic analysis (3), total nitrogen content (3), apparent N-acetyl-D-glucosamine content (4), optical rotation (3)) and viscosity (3). Since we had at hand a large number of preparations of group A substance obtained from hog gastric mucosa by a variety of methods (5), it was thought advisable to determine to what extent ultra-violet spectrophotometry could be used for the evaluation of these prepara