Somatic antigens of Shigella: Structure of the O-specific polysaccharide chain of the Shigella dysenteriae type 7 lipopolysaccharide

4-( N-Acetylglycyl)amino-4,6-dideoxy- d-glucose has been identified as a component of the Shigella dysenteriae type 7 O-specific polysaccharide, in addition to the previously reported 2-acetamido-2-deoxy- d-glucose and 2-acetamido-2-deoxy- d-galacturonic acid. On the basis of selective cleavage with anhydrous hydrogen fluoride and analysis by 1H- and 13C-n.m.r. spectroscopy and f.a.b.-mass spectrometry, it was concluded that the tetrasaccharide repeating-unit of the polysaccharide has the following structure: ▪ where d-GalNAcAN is 2-acetamido-2-deoxy- d-galacturonamide and d-Qui4N is 4-amino-4,6-dideoxy- d-glucose.