Defense against chitin-containing fungal pathogens (PubMed:1551872). Hydrolyzes glycol chitin and tetra-N-acetylchitotetraose in vitro (PubMed:28328103). Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Inactivated by l-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) in the absence of exogenous nucleophiles (e.g. GlcNAc4, GlcNAc3 and GlcNAc2) (PubMed:1740436). Not inhibited by tetra-N-acetylchitopentaose or modified chitotetraose substrate TMG-chitotriomycin-pMP, containing a free, non-acetylated glucosaminyl residue or a N-trimethylamino glucosamine (TMG) residue at the non-reducing terminus, respectively (PubMed:24616181). kcat is 56.27 sec(-1) with tetra-N-acetylchitotetraose as substrate (at 37 degrees Celsius and pH 6). kcat is 55.67 sec(-1) with tetra-N-acetylchitotetraose as substrate (at 37 degrees Celsius and pH 4). kcat is 69.01 sec(-1) with tetra-N-acetylchitotetraose as substrate (at 50 degrees Celsius and pH 6). kcat is 53.1 sec(-1) with tetra-N-acetylchitotetraose as substrate (at 70 degrees Celsius and pH 6). Active between pH 6-3. Active between 50-70 degrees Celsius. The N-terminal domain is not required for catalytic activity, but it is involved in substrate binding. Causes an allergic reaction in human. Food allergenic protein which binds IgE from sera of patients allergic to maize. Maize chitinase B seems to be less active than chitinase A. Belongs to the glycosyl hydrolase 19 family. Chitinase class IV subfamily.