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.
Glycosyl hydrolase family 43 protein most having a F5/8 type C domain C-terminal to the GH43 domain. This glycosyl hydrolase family 43 (GH43) subgroup includes enzymes that have been annotated as having beta-xylosidase (EC 3.2.1.37), xylanase (EC 3.2.1.8), and beta-galactosidase (EC 3.2.1.145) activities, and some as F5/8 type C domain (also known as the discoidin (DS) domain)-containing proteins. Most contain a F5/8 type C domain C-terminal to the GH43 domain. 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 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. Characterized enzymes belonging to this subgroup include Lactobacillus brevis (LbAraf43) and Weissella sp (WAraf43) which show activity with similar catalytic efficiency on 1,5-alpha-L-arabinooligosaccharides with a degree of polymerization (DP) of 2-3; size is limited by an extended loop at the entrance to the active site. 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 hydrolases family 43. The glycosyl hydrolase family 43 contains members that are arabinanases. Arabinanases hydrolyze the alpha-1,5-linked L-arabinofuranoside backbone of plant cell wall arabinans. The structure of arabinanase Arb43A from Cellvibrio japonicus reveals a five-bladed beta-propeller fold. 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, includes arabinoxylan arabinofuranohydrolase, beta-xylosidase, endo-1,4-beta-xylanase, and alpha-L-arabinofuranosidase. This subgroup includes Bacillus subtilis arabinoxylan arabinofuranohydrolase (XynD;BsAXH-m23;BSU18160), Butyrivibrio proteoclasticus alpha-L-arabinofuranosidase (Xsa43E;bpr_I2319), Clostridium stercorarium alpha-L-arabinofuranosidase XylA, and metagenomic beta-xylosidase (EC 3.2.1.37) / alpha-L-arabinofuranosidase (EC 3.2.1.55) CoXyl43. It belongs to the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. The GH43_AXH-like subgroup includes enzymes that have been characterized with beta-xylosidase, alpha-L-arabinofuranosidase, endo-alpha-L-arabinanase as well as arabinoxylan arabinofuranohydrolase (AXH) 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. AXHs specifically hydrolyze the glycosidic bond between arabinofuranosyl substituents and xylopyranosyl backbone residues of arabinoxylan. Metagenomic beta-xylosidase/alpha-L-arabinofuranosidase CoXyl43 shows synergy with Trichoderma reesei cellulases and promotes plant biomass saccharification by degrading xylo-oligosaccharides, such as xylobiose and xylotriose, into the monosaccharide xylose. Studies show that the hydrolytic activity of CoXyl43 is stimulated in the presence of calcium. Several of these enzymes also contain carbohydrate binding modules (CBMs) that bind cellulose or xylan. 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 family 43 such as Fibrobacter succinogenes subsp. succinogenes S85 arabinoxylan alpha-L-arabinofuranosidase. This glycosyl hydrolase family 43 (GH43) includes mostly enzymes that have been annotated as having beta-1,4-xylosidase (beta-D-xylosidase; xylan 1,4-beta-xylosidase; EC 3.2.1.37) activity. They are part of an array of hemicellulases that are involved in the final breakdown of plant cell-wall whereby they degrade xylan. They hydrolyze beta-1,4 glycosidic bonds between two xylose units in short xylooligosaccharides. 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. This subfamily includes the characterized Clostridium stercorarium F-9 beta-xylosidase Xyl43B. It also includes Humicola insolens AXHd3 (HiAXHd3), a GH43 arabinofuranosidase (EC 3.2.1.55) that hydrolyzes O3-linked arabinose of doubly substituted xylans, a feature of the polysaccharide that is recalcitrant to degradation. It possesses an additional C-terminal beta-sandwich domain such that the interface between the domains comprises a xylan binding cleft that houses the active site pocket. The HiAXHd3 active site is tuned to hydrolyze arabinofuranosyl or xylosyl linkages, and the topology of the distal regions of the substrate binding surface confers specificity. It also includes Fibrobacter succinogenes subsp. succinogenes S85 arabinoxylan alpha-L-arabinofuranosidase (Axh1;Fisuc_1769;FSU_2269), Paenibacillus sp. E18 alpha-L-arabinofuranosidase (Abf43A), Bifidobacterium adolescentis ATCC 15703 double substituted xylan alpha-1,3-L-specific arabinofuranosidase d3 (AXHd3;AXH-d3;BaAXH-d3;BAD_0301;E-AFAM2), and Chrysosporium lucknowense C1 arabinoxylan hydrolase / double substituted xylan alpha-1,3-L-arabinofuranosidase (Abn7;AXHd). 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.