KARL MEYER 



been clone, is that concerned with depolyTnerization and hydrolysis 

 of the neutral mucopolysaccharide fractions of gastric mucin. One 

 of these substances isolated from pig gastric mucosa is composed of 

 equimolar parts of acetylglucosamine and galactose (21). In these 

 mucopolysaccharide fractions some of the blood group substances 

 occur, substances responsible for the blood group specificities of man 

 and animal. Although the exact chemical composition of the blood 

 group substances is unknown at present, there seems little doubt that 

 the blood group A substance is closely related chemically to the 

 acetylglucosamine-galactose complexes of pig gastric mucosa. 



Enzymes which destroy the blood group A activity have been 

 found in human tissues, feces, and a few species of bacteria, among 

 them Clostridium welchii (39). From one of these strains SchifT ob- 

 tained a filtrate which inactivated the A but not the B substance. In 

 the writer's laboratory extracts of one strain of C. welchii were prepared 

 which hydrolyzed the polysaccharide of gastric mucosa with the 

 liberation of reducing sugar, while from other strains no such enzymes 

 were obtained (29). The blood group A activity was unaffected by 

 extracts from the nonhydrolyzing strain, while the hydrolysis by the 

 active extracts paralleled the A-inactivating potency (unpublished 

 work of Schiff and Meyer). The wide occurrence of glucosamine- 

 galactose complexes in many bacterial polysaccharides would make a 

 study of these enzymes quite interesting. 



Hyaliironidase 



Hyaluronidase is the most extensively studied of all mucolytic 

 enzymes. Its main substrate, hyaluronic acid, has been isolated from 

 vitreous humor, umbilical cord (30), synovial fluid (32), skin (26), and 

 some tumors of mesodermal origin, such as fowl leucosis (15,36) and a 

 human mesothelioma (25). One of the most significant findings in 

 this field was its isolation from group A and G hemolytic streptococci 

 by Kendall, Heidelberger, and Dawson (17). Hyaluronidase, an 

 enzyme which depolymerizes and hydrolyzes hyaluronic acid, was 

 first obtained from a type II pneumococcus (28). Although it was at 

 first thought that the enzyme was identical with the autolytic enzyme 

 of pneumococci, this proved not to be the case. Hyaluronidase was 

 found, shortly afterwards, in a group A hemolytic streptococcus, in a 



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