POLYSACCHARIDES 



115 



study of the pectic materials. Historically, interest in the pectic 

 enzymes was first stimulated by the discovery (13, 247) that crude 

 enzyme preparations from plant pathogenic fungi macerate plant 

 tissues by destruction of the middle lamella, the cementing material 

 between cells. First thought to be a cellulase, the tissue-macerating 

 enzyme has also been termed cytase. Other early studies are reviewed 

 by Brown (46). 



The insoluble pectic materials as the) are found in plants are now 

 called protopectin (116). Neither the structure nor the composition of 

 protopectin is known. The corresponding enzyme protopectinase 

 (pectosinase) is defined in principle as the enzyme converting proto- 

 pectin to water-soluble pectinic acids (255). Operationally, the 

 enzyme is defined by its ability to macerate blocks of living plant 

 tissue. It is found in pathogenic and non-pathogenic fungi belonging 

 to all of the major taxonomic groups (Table 3). 



Table 3. Occurrence of the Pectic Enzymes in the Fungi* 



Enzyme Occurrence 



"Protopectinase" Aspergillus spp. (61, 222), Botrytis spp. (46, 237), 



Byssochlamys julva (17, 105), Chaetomium globosum 

 (222), Daedalea flavida (32), Fomes jraxineus (152), 

 Fusarium spp. (51, 149, 211), Gloeosporium fructige- 

 num (Glomerella cingulata) (149), Lenzites sepiaria 

 (263), Macrophomina phaseoli (185), Metarrhizium 

 sp. (222), Moniliafructigena (237), Mucor racemosus 

 (93), Phytophthora erythroseptica (149), Polyporus 

 spp., Polystictus spp. (32), Pythium debaryanum (4, 

 97), Rhizoctonia sp. (258), Rhizopus spp. (94, 95), 

 Stereum purpureum (145), Trametes spp. (32). 

 Aspergillus spp. (81, 114), Botrytis cinerea (80), Fusa- 

 rium spp. (87, 241), Penicillium spp. (114, 176), 

 Sclerotinia cinerea (61), Sclerotiutn bataticola,\ Thiela- 

 viopsis basicola] (231). 

 Pectin-polygalacturonase Aspergillus spp. (6, 64, 81, 114, 208), Botrytis cinerea 



(81, 114, 257), Byssochlamys Julva (102, 192), Col- 

 letotrichum phomoides (185a), Fusarium spp. (47, 

 185a, 211, 241, 243), Mucor spp. (185a), Neuro- 

 spora spp. (64, 197), Penicillium spp. (64, 176, 185a, 

 243), Rhizopus nigricans (185a), Stachybolrys atra, 

 Syncephalastrum racemosum, Thamnidium elegans, Tri- 

 choderma spp. (64, 185a), Verticillium albo-atrum 

 (205). 

 * Including only the three major enzymes; for other enzyme activities, see 



text. 



f Assayed by hydrolysis of half-calcium salt of methyl-D-tartaric acid (157). 



Pectin-methylesterase 



