Glycosyl hydrolase family 43 protein such as endo-alpha-L-arabinanase. This glycosyl hydrolase family 43 (GH43) subgroup includes mostly enzymes with alpha-L-arabinofuranosidase (ABF; EC 3.2.1.55) and endo-alpha-L-arabinanase (ABN; EC 3.2.1.99) 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. The GH43 ABN enzymes hydrolyze alpha-1,5-L-arabinofuranoside linkages while the ABF enzymes cleave arabinose side chains so that the combined actions of these two enzymes reduce arabinan to L-arabinose and/or arabinooligosaccharides. These arabinan-degrading enzymes are important in the food industry for efficient production of L-arabinose from agricultural waste; L-arabinose is often used as a bioactive sweetener. 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 such as arabinan endo-1 5-alpha-L-arabinosidase. This glycosyl hydrolase family 43 (GH43) subgroup includes mostly enzymes with endo-alpha-L-arabinanase (ABN; EC 3.2.1.99) activity. 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. The GH43 ABN enzymes hydrolyze alpha-1,5-L-arabinofuranoside linkages. These arabinan-degrading enzymes are important in the food industry for efficient production of L-arabinose from agricultural waste; L-arabinose is often used as a bioactive sweetener. 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 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, beta-D-xylosidases and arabinofuranosidases. This glycosyl hydrolase family 43 (GH43) subgroup 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, including Selenomonas ruminantium beta-D-xylosidase SXA. These 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. It also includes various GH43 family GH43 arabinofuranosidases (EC 3.2.1.55) including Humicola insolens alpha-L-arabinofuranosidase AXHd3, Bacteroides ovatus alpha-L-arabinofuranosidase (BoGH43, XynB), and the bifunctional Phanerochaete chrysosporium xylosidase/arabinofuranosidase (Xyl;PcXyl). 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.

Crystalstructure of a thermostable family-43 glycoside hydrolase [Halothermothrix orenii H 168],4QQS_B Crystal structure of a thermostable family-43 glycoside hydrolase [Halothermothrix orenii H 168]

Bacteroidesovatus Xyloglucan PUL GH43B [Bacteroides ovatus],5JOZ_B Bacteroides ovatus Xyloglucan PUL GH43B [Bacteroides ovatus]

ChainA, xylan beta-1,4-xylosidase [Halalkalibacterium halodurans C-125],1YRZ_B Chain B, xylan beta-1,4-xylosidase [Halalkalibacterium halodurans C-125]

Bacteroidesovatus Xyloglucan PUL GH43A [Bacteroides ovatus ATCC 8483],5JOW_B Bacteroides ovatus Xyloglucan PUL GH43A [Bacteroides ovatus ATCC 8483],5JOX_A Bacteroides ovatus Xyloglucan PUL GH43A in complex with AraDNJ [Bacteroides ovatus],5JOX_B Bacteroides ovatus Xyloglucan PUL GH43A in complex with AraDNJ [Bacteroides ovatus],5JOY_A Bacteroides ovatus Xyloglucan PUL GH43A in complex with AraLOG [Bacteroides ovatus],5JOY_B Bacteroides ovatus Xyloglucan PUL GH43A in complex with AraLOG [Bacteroides ovatus]

Crystalstructure of the GH43 protein BlXynB mutant (K247S) from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580],6MS3_B Crystal structure of the GH43 protein BlXynB mutant (K247S) from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580]

Non-reducing end alpha-L-arabinofuranosidase BoGH43B OS=Bacteroides ovatus (strain ATCC 8483 / DSM 1896 / JCM 5824 / BCRC 10623 / CCUG 4943 / NCTC 11153) OX=411476 GN=BACOVA_02656 PE=1 SV=2

Non-reducing end alpha-L-arabinofuranosidase BoGH43A OS=Bacteroides ovatus (strain ATCC 8483 / DSM 1896 / JCM 5824 / BCRC 10623 / CCUG 4943 / NCTC 11153) OX=411476 GN=BACOVA_02654 PE=1 SV=1

Beta-xylosidase OS=Bacillus subtilis (strain 168) OX=224308 GN=xynB PE=1 SV=2

Beta-xylosidase OS=Bacillus pumilus OX=1408 GN=xynB PE=1 SV=2

Xylan 1,3-beta-xylosidase OS=Vibrio sp. OX=678 GN=xloA PE=1 SV=1