POLYSACCHARIDES 



119 



enzymes, as in that of so many other enzymes, is to determine the 

 action of single enzymes on substrates of definite and known com- 

 position. Once such information is available, there will be some hope 

 of successfully analyzing the more complex situation in nature. 



The Breakdown of Other Polysaccharides. It is generally con- 

 sidered that a special enzyme, inulase, catalyzes the breakdown of the 

 plant fructosan inulin. The enzyme was discovered in Aspergillus 

 niger by Bourquelot (37) and has since been found in many other 

 fungi (25, 59, 79). It has often been reported that cultivation on 

 inulin as carbon source increases the amount of enzyme (25, 184, 261), 

 but some inulase is always formed whatever the carbon source. No 

 systematic study of the enzyme or its occurrence has been made; some 

 properties of fungal inulase have been determined by Pigman (179), 

 and it is possible that two different enzymes are responsible for the 

 activity (153). On the other hand, there is some evidence that inulase 

 ;..', is a transfructosidase active also on sucrose (155a). 



A bacterial dextran, composed of anhydroglucose units linked by 

 1,6-crglucosidic bonds, is hydrolyzed by a dextranase present in the 

 mycelium and culture fluid of several fungi, e.g., Penicillium funicu- 

 losum, Verticillium coccorum, and Spicaria violacea (106, 234). The 

 enzyme is formed only if dextran is present in the medium. 



Limit dextrin, the polysaccharide fraction remaining after starch 

 hydrolysis by «-amylase, is hydrolyzed by a limit dextrinase from 

 Aspergillus oryzae; the enzyme has been crystallized (235). 



A commercial enzyme preparation, probably made from an Aspergil- 

 lus sp., hydrolyzes a galactogen of snail eggs, yielding d- and L-galactose 

 (248). 



Lichenin, the polysaccharide of Irish moss (Chondrus crispus) 

 resembles cellulose except for its high proportion of 1,3-glycosidic 

 bonds. It is hydrolyzed by an enzyme found in animal and plant 

 material (180) and in Aspergillus oryzae (200) and Merulius lacrymans 

 (181). Lichenase is probably distinct from cellulase and xylanase (78, 

 90). 



The mucopolysaccharides are complex polysaccharides yielding 

 amino sugars on hydrolysis (76); examples include hyaluronic acid, 

 chitin, agar, and unidentified cell wall materials. Among the enzymes 

 attacking these materials the bacterial hyaluronidase and lysozyme are 

 fairly well known, but the mucopolysaccharases of fungi are not. 

 Chitinases are known among actinomycetes and both higher and lower 

 fungi (49a, 233); the enzyme or enzymes responsible for chitin hydroly- 

 sis in Streptomyces sp. are adaptive (194). The lytic enzymes of 



