Glycosyl hydrolase family 32, such as the putative glycoside hydrolase Escherichia coli Aec43 (FosGH2). This glycosyl hydrolase family 32 (GH32) subgroup includes Escherichia coli strain BEN2908 putative glycoside hydrolase Aec43 (FosGH2). GH32 enzymes cleave sucrose into fructose and glucose via beta-fructofuranosidase activity, producing invert sugar that is a mixture of dextrorotatory D-glucose and levorotatory D-fructose, thus named invertase (EC 3.2.1.26). GH32 family also contains other fructofuranosidases such as inulinase (EC 3.2.1.7), exo-inulinase (EC 3.2.1.80), levanase (EC 3.2.1.65), and transfructosidases such sucrose:sucrose 1-fructosyltransferase (EC 2.4.1.99), fructan:fructan 1-fructosyltransferase (EC 2.4.1.100), sucrose:fructan 6-fructosyltransferase (EC 2.4.1.10), fructan:fructan 6G-fructosyltransferase (EC 2.4.1.243) and levan fructosyltransferases (EC 2.4.1.-). These retaining enzymes (i.e. they retain the configuration at anomeric carbon atom of the substrate) catalyze hydrolysis in two steps involving a covalent glycosyl enzyme intermediate: an aspartate located close to the N-terminus acts as the catalytic nucleophile and a glutamate acts as the general acid/base; a conserved aspartate residue in the Arg-Asp-Pro (RDP) motif stabilizes the transition state. These enzymes are predicted to display a 5-fold beta-propeller fold as found for GH43 and CH68. The breakdown of sucrose is widely used as a carbon or energy source by bacteria, fungi, and plants. Invertase is used commercially in the confectionery industry, since fructose has a sweeter taste than sucrose and a lower tendency to crystallize.
Glycoside hydrolase family 130. Members of the glycosyl hydrolase family 130, as classified by the carbohydrate-active enzymes database (CAZY), are phosphorylases and hydrolases for beta-mannosides, and include beta-1,4-mannosylglucose phosphorylase (EC 2.4.1.281), beta-1,4-mannooligosaccharide phosphorylase (EC 2.4.1.319), beta-1,4-mannosyl-N-acetyl-glucosamine phosphorylase (EC 2.4.1.320), beta-1,2-mannobiose phosphorylase (EC 2.4.1.-), beta-1,2-oligomannan phosphorylase (EC 2.4.1.-) and beta-1,2-mannosidase (EC 3.2.1.-). They possess 5-bladed beta-propeller domains similar to families 32, 43, 62, 68, 117 (GH32, GH43, GH62, GH68, GH117). GH130 enzymes are involved in the bacterial utilization of mannans or N-linked glycans. Beta-1,4-mannosylglucose phosphorylase is involved in degradation of beta-1,4-D-mannosyl-N-acetyl-D-glucosamine linkages in the core of N-glycans; it produces alpha-mannose 1-phosphate and glucose from 4-O-beta-D-mannosyl-D-glucose and inorganic phosphate, using a critical catalytic Asp as a proton donor.
