- The subfamilies of glycosyl hydrolases family 3 are distinguished by the sequence pattern next to the conserved KH (F/Y) motif (black boxed letters) at N-terminal domain adjacent to β-strand 5 of the N-terminal (β/α)8 barrel domain. The residues involved in the catalytic mechanism are boxed in light grey: while in β-glucosidases, a glutamate at a C-terminal region is responsible for the acid/base catalytic mechanism, N-acetylglucosaminidases are characterized by the D (S/T)H motif containing the Asp-His catalytic dyad [40]. Q9XEI3 and Q42835 are β-D-glucan exohydrolases from Hordeum vulgare, P33363 is BglX from E. coli, Q8GAT9 glucocerebrosidase from Paenibacillus sp. T12, P27034 is cellobiase from Rhizobium radiobacter, P75949 is Nag Z from E. coli, P40406 is NagZ from B. subtilis str. 168, P48823 is Cht60 from Pseudoalteromonas piscicida, O82840 is NagA from Streptomyces thermoviolaceus, Q6M204 is putative β-N-acetylglucosaminidase NagA2 from C. glutamicum ATCC13032
