From Pig Gastric Mucin and Human Ovarian Cyst Fluids by an Enzyme Preparation Obtained from Clostridium Welchii (type

Schiff (1935, 1939) reported that bacteria-free filtrates from cultures of certain strains of C108tridium welchii destroyed the serological character of the blood-group A substance in commercial pepsin and human saliva. This finding has been confirmed bymany workers. Meyer (1945) observed that an enzyme obtained from Cl. welchii liberated free reducing sugars from a neutral mucopolysaccharide which had been isolated from pig gastric mucin (Meyer, Smyth & Palmer, 1937) and which possessed high blood-group A activity. This carbohydrate was later shown to contain two neutral mucopolysaccharides, each of which had similar physical and chemical properties but showed a different serological specificity (Bendich, Kabat & Bezer, 1946; Aminoff, Morgan & Watkins, 1946; Chadwick, Smith, Annison & Morgan, 1949). The digestion of those pig-stomach linings which were free from blood-group A activity gave a neutral mucopolysaccharide which was closely similar in its physical, chemical and serological properties to a mucopolysaccharide found in the water-soluble secretions of the majority of persons belonging to blood group 0 (Landsteiner & Harte, 1941; Witebsky & Klendshoj, 1941; Morgan & Waddell, 1945). The serological specificity of this material has been designated by the symbol H (Morgan & Watkins, 1948, 1955). The H substance obtained from pig gastric mucosa is of special interest owing to its close similarity to the humanH substance and because it can be more easily obtained in a high state of purity and in amounts sufficient for detailed structural studies. An enzyme which brings about the rapid inactivation ofH substances ofhuman and animal origin was obtained from Cl. welchii (type B) culture filtrates by Stack & Morgan (1949), who devised a procedure for its purification, described a simple semi-quantitative method for the measurement of enzymic activity and recorded some properties of