Putative glycoside hydrolase Family 18, chitinase_18. This DUF is likely to be a form of glycosyl hydrolase from CAZy family 18, possibly chitinase 18. This would have the EC number of EC:3.2.1.14.
Endo-beta-N-acetylglucosaminidases are bacterial chitinases that hydrolyze the chitin core of various asparagine (N)-linked glycans and glycoproteins. The endo-beta-N-acetylglucosaminidases have a glycosyl hydrolase family 18 (GH18) catalytic domain. Some members also have an additional C-terminal glycosyl hydrolase family 20 (GH20) domain while others have an N-terminal domain of unknown function (pfam08522). Members of this family include endo-beta-N-acetylglucosaminidase S (EndoS) from Streptococcus pyogenes, EndoF1, EndoF2, EndoF3, and EndoH from Flavobacterium meningosepticum, and EndoE from Enterococcus faecalis. EndoS is a secreted endoglycosidase from Streptococcus pyogenes that specifically hydrolyzes the glycan on human IgG between two core N-acetylglucosamine residues. EndoE is a secreted endoglycosidase, encoded by the ndoE gene in Enterococcus faecalis, that hydrolyzes the glycan on human RNase B.
Cortical fragment-lytic enzyme (CFLE) is a peptidoglycan hydrolase involved in bacterial endospore germination. CFLE is expressed as an inactive preprotein (called SleB) in the forespore compartment of sporulating cells. SleB translocates across the forespore inner membrane and is deposited as a mature enzyme in the cortex layer of the spore. As part of a sensory mechanism capable of initiating germination, CFLE degrades a spore-specific peptidoglycan constituent called muramic-acid delta-lactam that comprises the outer cortex. CFLE has a C-terminal glycosyl hydrolase family 18 (GH18) catalytic domain as well as two N-terminal LysM peptidoglycan-binding domains. In addition to SleB, this family includes YaaH, YdhD, and YvbX from Bacillus subtilis.