Chitobiase (also known as di-N-acetylchitobiase) is a lysosomal glycosidase that hydrolyzes the reducing-end N-acetylglucosamine from the chitobiose core of oligosaccharides during the ordered degradation of asparagine-linked glycoproteins in eukaryotes. Chitobiase can only do so if the asparagine that joins the oligosaccharide to protein is previously removed by a glycosylasparaginase. Chitobiase is therefore the final step in the lysosomal degradation of the protein/carbohydrate linkage component of asparagine-linked glycoproteins. The catalytic domain of chitobiase is an eight-stranded alpha/beta barrel fold similar to that of other family 18 glycosyl hydrolases such as hevamine and chitotriosidase.