Glycosyl hydrolase family 43. This glycosyl hydrolase family 43 (GH43)-like subfamily includes uncharacterized enzymes similar to those with beta-1,4-xylosidase (xylan 1,4-beta-xylosidase; EC 3.2.1.37), beta-1,3-xylosidase (EC 3.2.1.-), alpha-L-arabinofuranosidase (EC 3.2.1.55), arabinanase (EC 3.2.1.99), xylanase (EC 3.2.1.8), endo-alpha-L-arabinanase and galactan 1,3-beta-galactosidase (EC 3.2.1.145) activities. These are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Many of the enzymes in this family display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. A common structural feature of GH43 enzymes is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.

Glycosyl hydrolase families 43 and 62 form CAZY clan GH-F. This glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) includes family 43 (GH43) and 62 (GH62). GH43 includes enzymes with beta-xylosidase (EC 3.2.1.37), beta-1,3-xylosidase (EC 3.2.1.-), alpha-L-arabinofuranosidase (EC 3.2.1.55), arabinanase (EC 3.2.1.99), xylanase (EC 3.2.1.8), endo-alpha-L-arabinanases (beta-xylanases) and galactan 1,3-beta-galactosidase (EC 3.2.1.145) activities. GH62 includes enzymes characterized as arabinofuranosidases (alpha-L-arabinofuranosidases; EC 3.2.1.55) that specifically cleave either alpha-1,2 or alpha-1,3-L-arabinofuranose side chains from xylans. GH43 are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Many of the enzymes in this family display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. GH62 are also predicted to be inverting enzymes. A common structural feature of both, GH43 and GH62 enzymes, is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.

Glycosyl hydrolase family 43 protein such as Bacteroides thetaiotaomicron VPI-5482 arabinofuranosidase Bt3655. This glycosyl hydrolase family 43 (GH43)-like family includes the characterized arabinofuranosidases (EC 3.2.1.55): Bacteroides thetaiotaomicron VPI-5482 (Bt3655;BT_3655) and Penicillium chrysogenum 31B Abf43B, as well as Bifidobacterium adolescentis ATCC 15703 beta-xylosidase (EC 3.2.1.37) BAD_1527. It belongs to the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. GH43 includes enzymes with beta-xylosidase (EC 3.2.1.37), beta-1,3-xylosidase (EC 3.2.1.-), alpha-L-arabinofuranosidase (EC 3.2.1.55), arabinanase (EC 3.2.1.99), xylanase (EC 3.2.1.8), endo-alpha-L-arabinanases (beta-xylanases) and galactan 1,3-beta-galactosidase (EC 3.2.1.145) activities. GH43 are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Many GH43 enzymes display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. A common structural feature of GH43 enzymes is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.

glycoside hydrolase family 32 sucrose 6 phosphate hydrolase (sucrase). Glycosyl hydrolase family GH32 subgroup contains sucrose-6-phosphate hydrolase (sucrase, EC:3.2.1.26) among others. The enzyme cleaves sucrose into fructose and glucose via beta-fructofuranosidase activity, producing invert sugar that is a mixture of dextrorotatory D-glucose and levorotatory D-fructose. 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. 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. A common structural feature of all these enzymes is a 5-bladed beta-propeller domain, similar to GH43, that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.

Glycosyl hydrolase family 43 protein such as Halothermothrix orenii H 168 alpha-L-arabinofuranosidase (HoAraf43;Hore_20580). This glycosyl hydrolase family 43 (GH43) subgroup includes Halothermothrix orenii H 168 alpha-L-arabinofuranosidase (EC 3.2.1.55) (HoAraf43;Hore_20580). It belongs to the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. This GH43_ HoAraf43-like subgroup includes enzymes that have been annotated as having xylan-digesting beta-xylosidase (EC 3.2.1.37) and xylanase (endo-alpha-L-arabinanase, EC 3.2.1.8) activities. GH43 are inverting enzymes (i.e. they invert the stereochemistry of the anomeric carbon atom of the substrate) that have an aspartate as the catalytic general base, a glutamate as the catalytic general acid and another aspartate that is responsible for pKa modulation and orienting the catalytic acid. Many GH43 enzymes display both alpha-L-arabinofuranosidase and beta-D-xylosidase activity using aryl-glycosides as substrates. A common structural feature of GH43 enzymes is a 5-bladed beta-propeller domain that contains the catalytic acid and catalytic base. A long V-shaped groove, partially enclosed at one end, forms a single extended substrate-binding surface across the face of the propeller.