Chitosanase catalyzing the endo-type cleavage of chitosan, the deacylated form of chitin. Chitosanase may be crucial in the degradation of the deacetylated portion of chitin in the fungal cell wall. Chitoolisaccharides produced by the hydrolysis of partially N-acetylated chitosan are known to have many biological activities, including antibacterial activity, immune-enhancing effects, and elicitor activity. The chitosans with higher degrees of deacetylation were shown to be the better substrates. Chitodimer, chitotrimer, and chitotetramer are the major products but monoacetyl chitodimer, monoacetyl chitotrimer, and monoacetyl chitotetramer are also produced (By similarity). Endohydrolysis of beta-(1->4)-linkages between D-glucosamine residues in a partly acetylated chitosan. Causes an allergic reaction in human. Binds to IgE (By similarity). Belongs to the glycosyl hydrolase 75 family.