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 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.

Glycosyl hydrolase family 43. 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 protein such as Aspergillus niger endo-alpha-L-arabinanase (AbnA). This glycosyl hydrolase family 43 (GH43) subgroup includes characterized enzymes with endo-alpha-L-arabinanase (ABN; EC 3.2.1.99) activities such as Aspergillus niger AbnA, Aspergillus niveus AbnA, and Chrysosporium lucknowense Abn1. It belongs to the GH43_Arb43a subgroup of the glycosyl hydrolase clan F (according to carbohydrate-active enzymes database (CAZY)) which includes family 43 (GH43) and 62 (GH62) families. GH43_Arb43a subgroup includes mostly enzymes with alpha-L-arabinofuranosidase (ABF; EC 3.2.1.55) and endo-alpha-L-arabinanase 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. The GH43_Arb43a subgroup includes many enzymes such as Bacillus subtilis arabinanase Abn2, that hydrolyzes sugar beet arabinan (branched), linear alpha-1,5-L-arabinan and pectin, and 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 the thermostable arabinanase [Geobacillus thermodenitrificans]

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

Crystalstructure of endo-arabinanase ABN-TS D147N mutant in complex with arabinohexaose [Geobacillus thermodenitrificans],6A8I_B Crystal structure of endo-arabinanase ABN-TS D147N mutant in complex with arabinohexaose [Geobacillus thermodenitrificans]

Crystalstructure of endo-arabinanase ABN-TS D27A mutant in complex with arabinotriose [Geobacillus thermodenitrificans]

GH43Endo-Arabinanase from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580],6B7K_B GH43 Endo-Arabinanase from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580],6B7K_C GH43 Endo-Arabinanase from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580],6B7K_D GH43 Endo-Arabinanase from Bacillus licheniformis [Bacillus licheniformis DSM 13 = ATCC 14580]

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 thermodenitrificans OX=33940 GN=abn-ts PE=1 SV=1

Probable arabinan endo-1,5-alpha-L-arabinosidase B OS=Neosartorya fischeri (strain ATCC 1020 / DSM 3700 / CBS 544.65 / FGSC A1164 / JCM 1740 / NRRL 181 / WB 181) OX=331117 GN=abnB PE=3 SV=2

Probable arabinan endo-1,5-alpha-L-arabinosidase B OS=Neosartorya fumigata (strain CEA10 / CBS 144.89 / FGSC A1163) OX=451804 GN=abnB PE=3 SV=2

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