Endo-beta-N-acetylglucosaminidase (ENGase) hydrolyzes the N-N'-diacetylchitobiosyl core of N-glycosylproteins. The beta-1,4-glycosyl bond located between two N-acetylglucosamine residues is hydrolyzed such that N-acetylglucosamine 1 remains with the protein and N-acetylglucosamine 2 forms the reducing end of the released glycan. ENGase is a key enzyme in the processing of free oligosaccharides in the cytosol of eukaryotes. Oligosaccharides formed in the lumen of the endoplasmic reticulum are transported into the cytosol where they are catabolized by cytosolic ENGases and other enzymes, possibly to maximize the reutilization of the component sugars. ENGases have an eight-stranded alpha/beta barrel topology and are classified as a family 85 glycosyl hydrolase (GH85) domain. The GH85 ENGases are sequence-similar to the family 18 glycosyl hydrolases, also known as GH18 chitinases. An ENGase-like protein is also found in bacteria and is included in this alignment model.