Xylanases occurrence

The culture filtrates of T. reesei contained a large number of both cellulolytic and hemicellulolytic enzymes, which could be partially separated by chromatofocussing (Fig. 1). Of the cellulolytic enzymes, several endoglu-canases and two cellobiohydrolases have already been isolated and characterized (30). Some of the endoglucanases isolated are nonspecific and have xylanase activity (31). The two major xylanase (Xyl) peaks in Figure 1 corresponded to pi-values of above 7.5 and 5.5. When the former enzyme was further purified (24), its isoelectric point was found to be about pi 9 (Table I). Previously, the presence of at least three electrophoretically different xylanases in T. reesei culture filtrates was reported, with the most acidic one shown to have broad substrate specificity (10). This is in agreement with the reported occurrence of three xylanases (pi > 7, pi 5.1, pi... 

The data presented in this work regarding xylanase production by B. circulans D1 point out the presence of a constitutive xylanase, produced in media with different carbon sources, besides xylan. In many of the reports regarding xylanase production, there is the occurrence of constitutive enzymes [23-26],... 

A review of the occurrence, purification, properties, and modes of action of hemicellulases has dealt with L-arabinanases, D-galactanases, D-mannanase, and D-xylanases, while a comprehensive review of pectolytic enzymes has discussed their classification and the assay and properties of pectinesterases and poly-D-galacturonate hydrolases and lyases. ... 

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