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.

Domain of unknown function (DUF4965). This family consists of uncharacterized proteins around 840 residues in length and is mainly found in various Bacteroides species. Several proteins in this family are annotated as Glutaminases, but the function of this protein is unknown.

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.

Domain of unknown function (DUF1793). This presumed domain is found at the C-terminus of a glutaminase protein from fungi. This domain is also found as a single domain protein in Bacteroides thetaiotaomicron.

Glycosyl hydrolase family 43 protein such as Bacillus subtilis subsp. subtilis str. 168 endo-alpha-1,5-L-arabinanase Arb43A. This glycosyl hydrolase family 43 (GH43) subgroup 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. 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. Many of these enzymes such as the Bacillus subtilis arabinanase Abn2, that hydrolyzes sugar beet arabinan (branched), linear alpha-1,5-L-arabinan and pectin, are different from other arabinases; they are organized into two different domains with a divalent metal cluster close to the catalytic residues to guarantee the correct protonation state of the catalytic residues and consequently the enzyme activity. 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.

Structureof Cellvibrio cellulosa alpha-L-arabinanase [Cellvibrio japonicus]

Structureof Cellvibrio cellulosa alpha-L-arabinanase complexed with Arabinohexaose [Cellvibrio japonicus]

Highresolution crystal structure of 1,5-alpha-L-arabinanase from Geobacillus Stearothermophilus [Geobacillus stearothermophilus]

Structureof D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus],1GYH_B Structure of D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus],1GYH_C Structure of D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus],1GYH_D Structure of D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus],1GYH_E Structure of D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus],1GYH_F Structure of D158A Cellvibrio cellulosa alpha-L-arabinanase mutant [Cellvibrio japonicus]

Structureof the thermostable arabinanase [Geobacillus thermodenitrificans]

Glutaminase A OS=Aspergillus oryzae (strain ATCC 42149 / RIB 40) OX=510516 GN=gtaA PE=1 SV=2

Probable glutaminase ARB_05535/05536 OS=Arthroderma benhamiae (strain ATCC MYA-4681 / CBS 112371) OX=663331 GN=ARB_05535/05536 PE=1 SV=2

Extracellular exo-alpha-(1->5)-L-arabinofuranosidase ArbA OS=Cellvibrio japonicus (strain Ueda107) OX=498211 GN=arbA PE=1 SV=1

Intracellular endo-alpha-(1->5)-L-arabinanase OS=Geobacillus stearothermophilus OX=1422 GN=abnB PE=1 SV=1

Intracellular endo-alpha-(1->5)-L-arabinanase OS=Geobacillus thermodenitrificans OX=33940 GN=abn-ts PE=1 SV=1