Enzyme Nomenclature

EC 3.2.1 (continued)

Hydrolysing O-Glycosyl Compounds

Continued from EC 3.2.1.1 to EC 3.2.1.50, EC 3.2.1.51 to EC 3.2.1.100 and EC 3.2.1.101 to EC 3.2.1.150

Contents

EC 3.2.1.151 xyloglucan-specific endo-β-1,4-glucanase
EC 3.2.1.152 mannosylglycoprotein endo-β-mannosidase
EC 3.2.1.153 fructan β-(2,1)-fructosidase
EC 3.2.1.154 fructan β-(2,6)-fructosidase
EC 3.2.1.155 xyloglucan-specific exo-β-1,4-glucanase
EC 3.2.1.156 oligosaccharide reducing-end xylanase
EC 3.2.1.157 ι-carrageenase
EC 3.2.1.158 α-agarase
EC 3.2.1.159 α-neoagaro-oligosaccharide hydrolase
EC 3.2.1.160 deleted, identical to EC 3.2.1.155
EC 3.2.1.161 β-apiosyl-β-glucosidase
EC 3.2.1.162 λ-carrageenase
EC 3.2.1.163 1,6-α-D-mannosidase
EC 3.2.1.164 galactan endo-1,6-β-galactosidase
EC 3.2.1.165 exo-1,4-β-D-glucosaminidase
EC 3.2.1.166 heparanase
EC 3.2.1.167 baicalin-β-D-glucuronidase
EC 3.2.1.168 hesperidin 6-O-α-L-rhamnosyl-β-D-glucosidase
EC 3.2.1.169 protein O-GlcNAcase
EC 3.2.1.170 mannosylglycerate hydrolase
EC 3.2.1.171 rhamnogalacturonan hydrolase
EC 3.2.1.172 unsaturated rhamnogalacturonyl hydrolase
EC 3.2.1.173 rhamnogalacturonan galacturonohydrolase
EC 3.2.1.174 rhamnogalacturonan rhamnohydrolase
EC 3.2.1.175 β-D-glucopyranosyl abscisate β-glucosidase
EC 3.2.1.176 cellulose 1,4-β-cellobiosidase (reducing end)
EC 3.2.1.177 α-D-xyloside xylohydrolase
EC 3.2.1.178 β-porphyranase
EC 3.2.1.179 gellan tetrasaccharide unsaturated glucuronyl hydrolase
EC 3.2.1.180 unsaturated chondroitin disaccharide hydrolase


Entries

EC 3.2.1.151

Accepted name: xyloglucan-specific endo-β-1,4-glucanase

Reaction: xyloglucan + H2O = xyloglucan oligosaccharides

Other name(s): XEG; xyloglucan endo-β-1,4-glucanase; xyloglucanase; xyloglucanendohydrolase; XH; 1,4-β-D-glucan glucanohydrolase

Systematic name: [(1→6)-α-D-xylo]-(1→4)-β-D-glucan glucanohydrolase

Comments: The enzyme for Aspergillus aculeatus is specific for xyloglucan and does not hydrolyse other cell-wall components. The reaction involves endohydrolysis of 1,4-β-D-glucosidic linkages in xyloglucan with retention of the β-configuration of the glycosyl residues.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 76901-10-5

References:

1. Pauly, M., Andersen, L.N., Kaupinnen, S., Kofod, L.V., York, W.S., Albersheim, P. and Darvill, A. A xyloglucan specific endo-β-1,4-glucanase from Aspergillus aculeatus: expression cloning in yeast, purification and characterization of the recombinant enzyme. Glycobiology 9 (1999) 93-100. [PMID: 9884411]

2. Grishutin, S.G., Gusakov, A.V., Markov, A.V., Ustinov, B.B., Semenova, M.V. and Sinitsyn, A.P. Specific xyloglucanases as a new class of polysaccharide-degrading enzymes. Biochim. Biophys. Acta 1674 (2004) 268-281. [PMID: 15541296]

[EC 3.2.1.151 created 2003]

EC 3.2.1.152

Accepted name: mannosylglycoprotein endo-β-mannosidase

Reaction: Hydrolysis of the α-D-mannosyl-(1arrow right6)-β-D-mannosyl-(1arrow right4)-β-D-N-acetylglucosaminyl-(1arrow right4)-β-D-N-acetylglucosaminyl sequence of glycoprotein to α-D-mannosyl-(1arrow right6)-D-mannose and β-D-N-acetylglucosaminyl-(1arrow right4)-β-D-N-acetylglucosaminyl sequences

Other name(s): endo-β-mannosidase

Comments: The substrate group is a substituent on N-4 of an asparagine residue in the glycoprotein. The mannose residue at the non-reducing end of the sequence may carry further α-D-mannosyl groups on O-3 or O-6, but such a substituent on O-3 of the β-D-mannosyl group prevents the action of the enzyme. The enzyme was obtained from the lily, Lilium longiflorum.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 141176-95-6

References:

1. Ishimizu, T., Sasaki, A., Okutani, S., Maeda, M., Yamagishi, M. and Hase, S. Endo-β-mannosidase, a plant enzyme acting on N-glycan. Purification, molecular cloning, and characterization. J. Biol. Chem. 279 (2004) 38555-38562. [PMID: 15247239]

2. Sasaki, A., Yamagishi, M., Mega, T., Norioka, S., Natsuka, S. and Hase, S. Partial purification and characterization of a novel endo-β-mannosidase acting on N-linked sugar chains from Lilium longiflorum thumb. J. Biochem. (Tokyo) 125 (1999) 363-367. [PMID: 9990135]

[EC 3.2.1.152 created 2005]

EC 3.2.1.153

Accepted name: fructan β-(2,1)-fructosidase

Reaction: Hydrolysis of terminal, non-reducing (2→1)-linked β-D-fructofuranose residues in fructans

For diagram click here.

Other name(s): β-(2-1)-D-fructan fructohydrolase; β-(2-1)fructan exohydrolase; inulinase; 1-FEH II; 1-fructan exohydrolase; 1-FEH w1; 1-FEH w2; β-(2-1)-linkage-specific fructan-β-fructosidase

Systematic name: β-(2,1)-D-fructan fructohydrolase

Comments: Possesses one of the activities of EC 3.2.1.80, fructan β-fructosidase. While the best substrates are the inulin-type fructans, such as 1-kestose (β-D-fructofuranosyl-(2arrow right1)-β-D-fructofuranosyl α-D-glucopyranoside) and 1,1-nystose (β-D-fructofuranosyl-(2arrow right1)-β-D-fructofuranosyl-(2arrow right1)-β-D-fructofuranosyl α-D-glucopyranoside), some (but not all) levan-type fructans can also be hydrolysed, but more slowly [see EC 3.2.1.154, fructan β-(2,6)-fructosidase]. Sucrose, while being a very poor substrate, can substantially inhibit enzyme activity in some cases.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 1000593-08-7

References:

1. De Roover, J., Van Laere, A., De Winter, M., Timmermans, J.W. and Van den Ende, W. Purification and properties of a second fructan exohydrolase from the roots of Cichorium intybus. Physiol. Plant. 106 (1999) 28-34.

2. Van den Ende, W., Clerens, S., Vergauwen, R., Van Riet, L., Van Laere, A., Yoshida, M. and Kawakami, A. Fructan 1-exohydrolases. β-(2,1)-Trimmers during graminan biosynthesis in stems of wheat? Purification, characterization, mass mapping, and cloning of two fructan 1-exohydrolase isoforms. Plant Physiol. 131 (2003) 621-631. [PMID: 12586886]

[EC 3.2.1.153 created 2005]

EC 3.2.1.154

Accepted name: fructan β-(2,6)-fructosidase

Reaction: Hydrolysis of terminal, non-reducing (2→6)-linked β-D-fructofuranose residues in fructans

For diagram click here.

Other name(s): β-(2-6)-fructan exohydrolase; levanase; 6-FEH; β-(2,6)-D-fructan fructohydrolase

Systematic name: (2→6)-β-D-fructan fructohydrolase

Comments: Possesses one of the activities of EC 3.2.1.80, fructan β-fructosidase. While the best substrates are the levan-type fructans such as 6-kestotriose [β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl α-D-glucopyranoside] and 6,6-kestotetraose [β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl-(2→6)-β-D-fructofuranosyl α-D-glucopyranoside], some (but not all) inulin-type fructans can also be hydrolysed, but more slowly [cf. EC 3.2.1.153, fructan β-(2,1)-fructosidase). Sucrose, while being a very poor substrate, can substantially inhibit enzyme activity in some cases.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 1000597-62-5

References:

1. Marx, S.P., Nösberger, J. and Frehner, M. Hydrolysis of fructan in grasses: A β-(2-6)-linkage specific fructan-β-fructosidase from stubble of Lolium perenne. New Phytol. 135 (1997) 279-290.

2. Van den Ende, W., De Coninck, B., Clerens, S., Vergauwen, R. and Van Laere, A. Unexpected presence of fructan 6-exohydrolases (6-FEHs) in non-fructan plants: characterization, cloning, mass mapping and functional analysis of a novel 'cell-wall invertase-like' specific 6-FEH from sugar beet (Beta vulgaris L.). Plant J. 36 (2003) 697-710. [PMID: 14617070]

3. Henson, C.A. and Livingston, D.P., III. Purification and characterization of an oat fructan exohydrolase that preferentially hydrolyzes β-2,6-fructans. Plant Physiol. 110 (1996) 639-644.

[EC 3.2.1.154 created 2005]

EC 3.2.1.155

Accepted name: xyloglucan-specific exo-β-1,4-glucanase

Reaction: Hydrolysis of (1→4)-D-glucosidic linkages in xyloglucans so as to successively remove oligosaccharides from the chain end.

Other name(s): Cel74A

Systematic name: [(1→6)-α-D-xylo]-(1→4)-β-D-glucan exo-glucohydrolase

Comments: The enzyme removes XXXG heptasaccharides, XXLG/XLXG octasaccharides and XLLG nonasaccharides from the end of tamarind seed xyloglucan polymers in a processive manner. Hydrolysis occurs at the unsubstituted D-glucopyranose residue in the main backbone. It is not known whether the cleavage takes place at the reducing or non-reducing end of the polymer. Very low activity with β-D-glucans. The enzyme from Chrysosporium lucknowense shifts to an endoglucanase mode when acting on linear substrates without bulky substituents on the polymeric backbone such as barley β-glucan.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 1000598-79-7

References:

1. Grishutin, S.G., Gusakov, A.V., Markov, A.V., Ustinov, B.B., Semenova, M.V. and Sinitsyn, A.P. Specific xyloglucanases as a new class of polysaccharide-degrading enzymes. Biochim. Biophys. Acta 1674 (2004) 268-281. [PMID: 15541296]

[EC 3.2.1.155 created 2005, withdrawn at public-review stage, modified and reinstated 2006, modified 2011]

EC 3.2.1.156

Accepted name: oligosaccharide reducing-end xylanase

Reaction: Hydrolysis of (1→4)-β-D-xylose residues from the reducing end of oligosaccharides

Other name(s): Rex; reducing end xylose-releasing exo-oligoxylanase

Systematic name: β-D-xylopyranosyl-(1→4)-β-D-xylopyranose reducing-end xylanase

Comments: The enzyme acts rapidly on the β-anomer of β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose, leaving the new reducing end in the α configuration. It also acts on longer oligosaccharides that have this structure at their reducing ends. The penultimate residue must be xylose, but replacing either of the other two residues with glucose merely slows the rate greatly.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 879497-03-7

References:

1. Honda, Y. and Kitaoka, M. A family 8 glycoside hydrolase from Bacillus halodurans C-125 (BH2105) is a reducing end xylose-releasing exo-oligoxylanase. J. Biol. Chem. 279 (2004) 55097-55103. [PMID: 15491996]

2. Fushinobu, S., Hidaka, M., Honda, Y., Wakagi, T., Shoun, H. and Kitaoka, M. Structural basis for the specificity of the reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125. J. Biol. Chem. 2005 Feb 17 [Epub ahead of print] [PMID: 15718242]

[EC 3.2.1.156 created 2005]

EC 3.2.1.157

Accepted name: ι-carrageenase

Reaction: Endohydrolysis of (1→4)-β-D-linkages between D-galactose 4-sulfate and 3,6-anhydro-D-galactose-2-sulfate in ι-carrageenans

For diagram, click here

Glossary: In the field of oligosaccharides derived from agarose, carrageenans, etc., in which alternate residues are 3,6-anhydro sugars, the prefix 'neo' designates an oligosaccharide whose non-reducing end is the anhydro sugar, and the absence of this prefix means that it is not.
For example:
ι-neocarrabiose = 3,6-anhydro-2-O-sulfo-α-D-galactopyranosyl-(1→3)-4-O-sulfo-D-galactose
ι-carrabiose = 4-O-sulfo-β-D-galactopyranosyl-(1→4)-3,6-anhydro-2-O-sulfo-D-galactose

Systematic name: ι-carrageenan 4-β-D-glycanohydrolase (configuration-inverting)

Comments: The main products of hydrolysis are ι-neocarratetraose sulfate and ι-neocarrahexaose sulfate. ι-Neocarraoctaose is the shortest substrate oligomer that can be cleaved. Unlike EC 3.2.1.81, β-agarase and EC 3.2.1.83, κ-carrageenase, this enzyme proceeds with inversion of the anomeric configuration. ι-Carrageenan differs from κ-carrageenan by possessing a sulfo group on O-2 of the 3,6-anhydro-D-galactose residues, in addition to that present in the κ-compound on O-4 of the D-galactose residues.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 50936-37-3

References:

1. Barbeyron, T., Michel, G., Potin, P., Henrissat, B. and Kloareg, B. ι-Carrageenases constitute a novel family of glycoside hydrolases, unrelated to that of κ-carrageenases. J. Biol. Chem. 275 (2000) 35499-35505. [PMID: 10934194]

2. Michel, G., Chantalat, L., Fanchon, E., Henrissat, B., Kloareg, B. and Dideberg, O. The ι-carrageenase of Alteromonas fortis. A β-helix fold-containing enzyme for the degradation of a highly polyanionic polysaccharide. J. Biol. Chem. 276 (2001) 40202-40209. [PMID: 11493601]

3. Michel, G., Helbert, W., Kahn, R., Dideberg, O. and Kloareg, B. The structural bases of the processive degradation of ι-carrageenan, a main cell wall polysaccharide of red algae. J. Mol. Biol. 334 (2003) 421-433. [PMID: 14623184]

[EC 3.2.1.157 created 2006]

EC 3.2.1.158

Accepted name: α-agarase

Reaction: Endohydrolysis of 1,3-α-L-galactosidic linkages in agarose, yielding agarotetraose as the major product

Glossary: agarose = a polysaccharide
In the field of oligosaccharides derived from agarose, carrageenans, etc., in which alternate residues are 3,6-anhydro sugars, the prefix 'neo' designates an oligosaccharide whose non-reducing end is the anhydro sugar, and the absence of this prefix means that it is not.
For example:
neoagarobiose = 3,6-anhydro-α-L-galactopyranosyl-(1→3)-D-galactose
agarobiose = β-D-galactopyranosyl-(1→4)-3,6-anhydro-L-galactose

Other name(s): agarase (ambiguous); agaraseA33

Systematic name: agarose 3-glycanohydrolase

Comments: Requires Ca2+. The enzyme from Thalassomonas sp. can use agarose, agarohexaose and neoagarohexaose as substrate. The products of agarohexaose hydrolysis are dimers and tetramers, with agarotetraose being the predominant product, whereas hydrolysis of neoagarohexaose gives rise to two types of trimer. While the enzyme can also hydrolyse the highly sulfated agarose porphyran very efficiently, it cannot hydrolyse the related compounds κ-carrageenan (see EC 3.2.1.83) and ι-carrageenan (see EC 3.2.1.157) [2]. See also EC 3.2.1.81, β-agarase.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 63952-00-1

References:

1. Potin, P., Richard, C., Rochas, C. and Kloareg, B. Purification and characterization of the α-agarase from Alteromonas agarlyticus (Cataldi) comb. nov., strain GJ1B. Eur. J. Biochem. 214 (1993) 599-607. [PMID: 8513809]

2. Ohta, Y., Hatada, Y., Miyazaki, M., Nogi, Y., Ito, S. and Horikoshi, K. Purification and characterization of a novel α-agarase from a Thalassomonas sp. Curr. Microbiol. 50 (2005) 212-216. [PMID: 15902469]

[EC 3.2.1.158 created 2006]

EC 3.2.1.159

Accepted name: α-neoagaro-oligosaccharide hydrolase

Reaction: Hydrolysis of the 1,3-α-L-galactosidic linkages of neoagaro-oligosaccharides that are smaller than a hexamer, yielding 3,6-anhydro-L-galactose and D-galactose

Glossary: In the field of oligosaccharides derived from agarose, carrageenans, etc., in which alternate residues are 3,6-anhydro sugars, the prefix 'neo' designates an oligosaccharide whose non-reducing end is the anhydro sugar, and the absence of this prefix means that it is not.
For example:
neoagarobiose = 3,6-anhydro-α-L-galactopyranosyl-(1→3)-D-galactose
agarobiose = β-D-galactopyranosyl-(1→4)-3,6-anhydro-L-galactose

Other name(s): α-neoagarooligosaccharide hydrolase; α-NAOS hydrolase

Systematic name: α-neoagaro-oligosaccharide 3-glycohydrolase

Comments: When neoagarohexaose is used as a substrate, the oligosaccharide is cleaved at the non-reducing end to produce 3,6-anhydro-L-galactose and agaropentaose, which is further hydrolysed to agarobiose and agarotriose. With neoagarotetraose as substrate, the products are predominantly agarotriose and 3,6-anhydro-L-galactose. In Vibrio sp. the actions of EC 3.2.1.81, β-agarase and EC 3.2.1.159 can be used to degrade agarose to 3,6-anhydro-L-galactose and D-galactose.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 60063-77-6

References:

1. Sugano, Y., Kodama, H., Terada, I., Yamazaki, Y. and Noma, M. Purification and characterization of a novel enzyme, α-neoagarooligosaccharide hydrolase (α-NAOS hydrolase), from a marine bacterium, Vibrio sp. strain JT0107. J. Bacteriol. 176 (1994) 6812-6818. [PMID: 7961439]

[EC 3.2.1.159 created 2006]

[EC 3.2.1.160 Deleted entry: xyloglucan-specific exo-β-1,4-glucanase. The enzyme was shown to be identical to EC 3.2.1.155, xyloglucan-specific exo-β-1,4-glucanase, during the public-review process so was withdrawn before being made official. (EC 3.2.1.160 created 2006, deleted 2006)]

EC 3.2.1.161

Accepted name: β-apiosyl-β-glucosidase

Reaction: 7-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyloxy]isoflavonoid + H2O = a 7-hydroxyisoflavonoid + β-D-apiofuranosyl-(1→6)-D-glucose

Other name(s): isoflavonoid-7-O-β[D-apiosyl-(1→6)-β-D-glucoside] disaccharidase; isoflavonoid 7-O-β-apiosyl-glucoside β-glucosidase; furcatin hydrolase

Systematic name: 7-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranosyloxy]isoflavonoid β-D-apiofuranosyl-(1→6)-D-glucohydrolase

Comments: The enzyme from the tropical tree Dalbergia nigrescens Kurz belongs in glycosyl hydrolase family 1. The enzyme removes disaccharides from the natural substrates dalpatein 7-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside and 7-hydroxy-2',4',5',6-tetramethoxy-7-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (dalnigrein 7-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside) although it can also remove a single glucose residue from isoflavonoid 7-O-glucosides [2]. Daidzin and genistin are also substrates.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number: 1000593-83-3

References:

1. Hosel, W. and Barz, W. β-Glucosidases from Cicer arietinum L. Purification and Properties of isoflavone-7-O-glucoside-specific β-glucosidases. Eur. J. Biochem. 57 (1975) 607-616. [PMID: 240725]

2. Chuankhayan, P., Hua, Y., Svasti, J., Sakdarat, S., Sullivan, P.A. and Ketudat Cairns, J.R. Purification of an isoflavonoid 7-O-β-apiosyl-glucoside β-glycosidase and its substrates from Dalbergia nigrescens Kurz. Phytochemistry 66 (2005) 1880-1889. [PMID: 16098548]

3. Ahn, Y.O., Mizutani, M., Saino, H. and Sakata, K. Furcatin hydrolase from Viburnum furcatum Blume is a novel disaccharide-specific acuminosidase in glycosyl hydrolase family 1. J. Biol. Chem. 279 (2004) 23405-23414. [PMID: 14976214]

[EC 3.2.1.161 created 2006]

EC 3.2.1.162

Accepted name: λ-carrageenase

Reaction: Endohydrolysis of (1→4)-β-linkages in the backbone of λ-carrageenan, resulting in the tetrasaccharide α-D-Galp2,6S2-(1→3)-β-D-Galp2S-(1→4)-α-D-Galp2,6S2-(1→3)-D-Galp2S

For diagram click here.

Glossary: carrageenan

Other name(s): endo-β-1,4-carrageenose 2,6,2'-trisulfate-hydrolase

Systematic name: endo-(1→4)-β-carrageenose 2,6,2'-trisulfate-hydrolase

Comments: The enzyme from Pseudoalteromonas sp. is specific for λ-carrageenan. ι-Carrageenan (see EC 3.2.1.157, ι-carrageenase), κ-carrageenan (see EC 3.2.1.83, κ-carrageenase), agarose and porphyran are not substrates.

Links to other databases: BRENDA, EXPASY, KEGG, PDB, CAS registry number:

References:

1. Ohta, Y. and Hatada, Y. A novel enzyme, λ-carrageenase, isolated from a deep-sea bacterium. J. Biochem. (Tokyo) 140 (2006) 475-481. [PMID: 16926183]

[EC 3.2.1.162 created 2007]

EC 3.2.1.163

Accepted name: 1,6-α-D-mannosidase

Reaction: Hydrolysis of the 1,6-linked α-D-mannose residues in α-D-Manp-(1→6)-D-Manp

Systematic name: 1,6-α-mannosyl α-D-mannohydrolase

Comments: The enzyme is specific for (1→6)-linked mannobiose and has no activity towards any other linkages, or towards p-nitrophenyl-α-D-mannopyranoside or baker's yeast mannan. It is strongly inhibited by Mn2+ but does not require Ca2+ or any other metal cofactor for activity.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Athanasopoulos, V.I., Niranjan, K. and Rastall, R.A. The production, purification and characterisation of two novel α-D-mannosidases from Aspergillus phoenicis. Carbohydr. Res. 340 (2005) 609-617. [PMID: 15721331]

[EC 3.2.1.163 created 2007]

EC 3.2.1.164

Accepted name: galactan endo-1,6-β-galactosidase

Reaction: Endohydrolysis of (1→6)-β-D-galactosidic linkages in arabinogalactan proteins and (1→3):(1→6)-β-galactans to yield galactose and (1→6)-β-galactobiose as the final products

Other name(s): endo-1,6-β-galactanase; endo-β-(1→6)-galactanase

Comments: The enzyme specifically hydrolyses 1,6-β-D-galactooligosaccharides with a degree of polymerization (DP) higher than 3, and their acidic derivatives with 4-O-methylglucosyluronate or glucosyluronate groups at the non-reducing terminals [2]. 1,3-β-D- and 1,4-β-D-galactosyl residues cannot act as substrates. The enzyme can also hydrolyse α-L-arabinofuranosidase-treated arabinogalactan protein (AGP) extracted from radish roots [2,3]. AGPs are thought to be involved in many physiological events, such as cell division, cell expansion and cell death [3].

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Brillouet, J.-M., Williams, P. and Moutounet, M. Purification and some properties of a novel endo-β-(1→6)-D-galactanase from Aspergillus niger. Agric. Biol. Chem. 55 (1991) 1565-1571.

2. Okemoto, K., Uekita, T., Tsumuraya, Y., Hashimoto, Y. and Kasama, T. Purification and characterization of an endo-β-(1→6)-galactanase from Trichoderma viride. Carbohydr. Res. 338 (2003) 219-230. [PMID: 12543554]

3. Kotake, T., Kaneko, S., Kubomoto, A., Haque, M.A., Kobayashi, H. and Tsumuraya, Y. Molecular cloning and expression in Escherichia coli of a Trichoderma viride endo-β-(1→6)-galactanase gene. Biochem. J. 377 (2004) 749-755. [PMID: 14565843]

[EC 3.2.1.164 created 2007]

EC 3.2.1.165

Accepted name: exo-1,4-β-D-glucosaminidase

Reaction: Hydrolysis of chitosan or chitosan oligosaccharides to remove successive D-glucosamine residues from the non-reducing termini

Glossary: GlcN = D-glucosamine = 2-amino-2-deoxy-D-glucopyranose
GlcNAc = N-acetyl-D-glucosamine

Other name(s): CsxA; GlcNase; exochitosanase; GlmA; exo-β-D-glucosaminidase

Systematic name: chitosan exo-(1→4)-β-D-glucosaminidase

Comments: Chitosan is a partially or totally N-deacetylated chitin derivative that is found in the cell walls of some phytopathogenic fungi and comprises D-glucosamine residues with a variable content of GlcNAc residues [4]. Acts specifically on chitooligosaccharides and chitosan, having maximal activity on chitotetraose, chitopentaose and their corresponding alcohols [1]. The enzyme can degrade GlcN-GlcNAc but not GlcNAc-GlcNAc [3]. A member of the glycoside hydrolase family 2 (GH-2) [4].

References:

1. Nanjo, F., Katsumi, R. and Sakai, K. Purification and characterization of an exo-β-D-glucosaminidase, a novel type of enzyme, from Nocardia orientalis. J. Biol. Chem. 265 (1990) 10088-10094. [PMID: 2351651]

2. Nogawa, M., Takahashi, H., Kashiwagi, A., Ohshima, K., Okada, H. and Morikawa, Y. Purification and characterization of exo-β-D-glucosaminidase from a cellulolytic fungus, Trichoderma reesei PC-3-7. Appl. Environ. Microbiol. 64 (1998) 890-895. [PMID: 16349528]

3. Fukamizo, T., Fleury, A., Côté, N., Mitsutomi, M. and Brzezinski, R. Exo-β-D-glucosaminidase from Amycolatopsis orientalis: catalytic residues, sugar recognition specificity, kinetics, and synergism. Glycobiology 16 (2006) 1064-1072. [PMID: 16877749]

4. Côté, N., Fleury, A., Dumont-Blanchette, E., Fukamizo, T., Mitsutomi, M. and Brzezinski, R. Two exo-β-D-glucosaminidases/exochitosanases from actinomycetes define a new subfamily within family 2 of glycoside hydrolases. Biochem. J. 394:675 (2006). [PMID: 16316314]

5. Ike, M., Isami, K., Tanabe, Y., Nogawa, M., Ogasawara, W., Okada, H. and Morikawa, Y. Cloning and heterologous expression of the exo-β-D-glucosaminidase-encoding gene (gls93) from a filamentous fungus, Trichoderma reesei PC-3-7. Appl. Microbiol. Biotechnol. 72 (2006) 687-695. [PMID: 16636831]

[EC 3.2.1.165 created 2008]

EC 3.2.1.166

Accepted name: heparanase

Reaction: endohydrolysis of (1→4)-β-D-glycosidic bonds of heparan sulfate chains in heparan sulfate proteoglycan

Other name(s): Hpa1 heparanase; Hpa1; heparanase 1; heparanase-1; C1A heparanase; HPSE

Systematic name: heparan sulfate N-sulfo-D-glucosamine endoglucanase

Comments: Heparanase cleaves the linkage between a glucuronic acid unit and an N-sulfo glucosamine unit carrying either a 3-O-sulfo or a 6-O-sulfo group [2]. Heparanase-1 cuts macromolecular heparin into fragments of 5000-20000 Da [5]. The enzyme cleaves the heparan sulfate glycosaminoglycans from proteoglycan core proteins and degrades them to small oligosaccharides. Inside cells, the enzyme is important for the normal catabolism of heparan sulfate proteoglycans, generating glycosaminoglycan fragments that are then transported to lysosomes and completely degraded. When secreted, heparanase degrades basement membrane heparan sulfate glycosaminoglycans at sites of injury or inflammation, allowing extravasion of immune cells into nonvascular spaces and releasing factors that regulate cell proliferation and angiogenesis [1].

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Bame, K.J. Heparanases: endoglycosidases that degrade heparan sulfate proteoglycans. Glycobiology 11 (2001) 91R-98R. [PMID: 11445547]

2. Peterson, S.B. and Liu, J. Unraveling the specificity of heparanase utilizing synthetic substrates. J. Biol. Chem. 285 (2010) 14504-14513. [PMID: 20181948]

3. Pikas, D.S., Li, J.P., Vlodavsky, I. and Lindahl, U. Substrate specificity of heparanases from human hepatoma and platelets. J. Biol. Chem. 273 (1998) 18770-18777. [PMID: 9668050]

4. Okada, Y., Yamada, S., Toyoshima, M., Dong, J., Nakajima, M. and Sugahara, K. Structural recognition by recombinant human heparanase that plays critical roles in tumor metastasis. Hierarchical sulfate groups with different effects and the essential target disulfated trisaccharide sequence. J. Biol. Chem. 277 (2002) 42488-42495. [PMID: 12213822]

5. Vreys, V. and David, G. Mammalian heparanase: what is the message. J Cell Mol Med 11 (2007) 427-452. [PMID: 17635638]

6. Gong, F., Jemth, P., Escobar Galvis, M.L., Vlodavsky, I., Horner, A., Lindahl, U. and Li, J.P. Processing of macromolecular heparin by heparanase. J. Biol. Chem. 278 (2003) 35152-35158. [PMID: 12837765]

7. Toyoshima, M. and Nakajima, M. Human heparanase. Purification, characterization, cloning, and expression. J. Biol. Chem. 274 (1999) 24153-24160. [PMID: 10446189]

8. Miao, H.Q., Navarro, E., Patel, S., Sargent, D., Koo, H., Wan, H., Plata, A., Zhou, Q., Ludwig, D., Bohlen, P. and Kussie, P. Cloning, expression, and purification of mouse heparanase. Protein Expr. Purif. 26 (2002) 425-431. [PMID: 12460766]

9. Hammond, E., Li, C.P. and Ferro, V. Development of a colorimetric assay for heparanase activity suitable for kinetic analysis and inhibitor screening. Anal. Biochem. 396 (2010) 112-116. [PMID: 19748475]

[EC 3.2.1.166 created 2010]

EC 3.2.1.167

Accepted name: baicalin-β-D-glucuronidase

Reaction: baicalin + H2O = baicalein + D-glucuronate

Glossary: baicalin = 5,6,7-trihydroxyflavone-7-O-β-D-glucuronate = 5,6-dihydroxy-4-oxo-2-phenyl-4H-chromen-7-yl β-D-glucupyranosiduronic acid
baicalein = 5,6,7-trihydroxyflavone = 5,6,7-trihydroxy-2-phenyl-4H-chromen-4-one
wogonin = 5,7-dihydroxy-8-methoxyflavone = 5,7-dihydroxy-8-methoxy-2-phenyl-4H-chromen-4-one
oroxylin = 5,7-dihydroxy-6-methoxyflavone = 5,7-dihydroxy-6-methoxy-2-phenyl-4H-1-benzopyran-4-one

Other name(s): baicalinase

Systematic name: 5,6,7-trihydroxyflavone-7-O-β-D-glucupyranosiduronate glucuronosylhydrolase

Comments: The enzyme also hydrolyses wogonin 7-O-β-D-glucuronide and oroxylin 7-O-β-D-glucuronide with lower efficiency [4]. Neglegible activity with p-nitrophenyl-β-D-glucuronide [2].

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Ikegami, F., Matsunae, K., Hisamitsu, M., Kurihara, T., Yamamoto, T. and Murakoshi, I. Purification and properties of a plant β-D-glucuronidase form Scutellaria root. Biol. Pharm. Bull. 18 (1995) 1531-1534. [PMID: 8593473]

2. Zhang, C., Zhang, Y., Chen, J. and Liang, X. Purification and characterization of baicalin-β-D-glucuronidase hydrolyzing baicalin to baicalein from fresh roots of Scutellaria viscidula Bge. Proc. Biochem. 40 (2005) 1911-1915.

3. Sasaki, K., Taura, F., Shoyama, Y. and Morimoto, S. Molecular characterization of a novel β-glucuronidase from Scutellaria baicalensis Georgi. J. Biol. Chem. 275 (2000) 27466-27472. [PMID: 10858442]

4. Morimoto, S., Harioka, T. and Shoyama, Y. Purification and characterization of flavone-specific β-glucuronidase from callus cultures of Scutellaria baicalensis Georgi. Planta 195 (1995) 535-540.

[EC 3.2.1.167 created 2011]

EC 3.2.1.168

Accepted name: hesperidin 6-O-α-L-rhamnosyl-β-D-glucosidase

Reaction: hesperidin + H2O = hesperitin + rutinose

Glossary: hesperitin = 5,7,3'-trihydroxy-4'-methoxyflavanone
hesperidin = hesperitin 7-(6-O-α-L-rhamnopyranosyl)-β-D-glucopyranoside
rutinose = 6-O-α-L-rhamnopyranosyl-D-glucose

Systematic name: hesperetin 7-(6-O-α-L-rhamnopyranosyl-β-D-glucopyranoside) 6-O-α-rhamnopyranosyl-β-glucohydrolase

Comments: The enzyme exhibits high specificity towards 7-O-linked flavonoid β-rutinosides.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Mazzaferro, L., Piñuel, L., Minig, M. and Breccia, J.D. Extracellular monoenzyme deglycosylation system of 7-O-linked flavonoid β-rutinosides and its disaccharide transglycosylation activity from Stilbella fimetaria. Arch. Microbiol. 192 (2010) 383-393; 193 (2011) 461. [PMID: 20358178]

[EC 3.2.1.168 created 2011]

EC 3.2.1.169

Accepted name: protein O-GlcNAcase

Reaction: (1) [protein]-3-O-(N-acetyl-β-D-glucosaminyl)-L-serine + H2O = [protein]-L-serine + N-acetyl-D-glucosamine
(2) [protein]-3-O-(N-acetyl-β-D-glucosaminyl)-L-theronine + H2O = [protein]-L-threonine + N-acetyl-D-glucosamine

Other name(s): OGA; glycoside hydrolase O-GlcNAcase; O-GlcNAcase; BtGH84; O-GlcNAc hydrolase

Systematic name: [protein]-3-O-(N-acetyl-β-D-glucosaminyl)-L-serine/threonine N-acetylglucosaminyl hydrolase

Comments: Within higher eukaryotes post-translational modification of protein serines/threonines with N-acetylglucosamine (O-GlcNAc) is dynamic, inducible and abundant, regulating many cellular processes by interfering with protein phosphorylation. EC 2.4.1.255 (protein O-GlcNAc transferase) transfers GlcNAc onto substrate proteins and EC 3.2.1.169 (protein O-GlcNAcase) cleaves GlcNAc from the modified proteins.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Gao, Y., Wells, L., Comer, F.I., Parker, G.J. and Hart, G.W. Dynamic O-glycosylation of nuclear and cytosolic proteins: cloning and characterization of a neutral, cytosolic β-N-acetylglucosaminidase from human brain. J. Biol. Chem. 276 (2001) 9838-9845. [PMID: 11148210]

2. Wells, L., Gao, Y., Mahoney, J.A., Vosseller, K., Chen, C., Rosen, A. and Hart, G.W. Dynamic O-glycosylation of nuclear and cytosolic proteins: further characterization of the nucleocytoplasmic β-N-acetylglucosaminidase, O-GlcNAcase. J. Biol. Chem. 277 (2002) 1755-1761. [PMID: 11788610]

3. Cetinbas, N., Macauley, M.S., Stubbs, K.A., Drapala, R. and Vocadlo, D.J. Identification of Asp174 and Asp175 as the key catalytic residues of human O-GlcNAcase by functional analysis of site-directed mutants. Biochemistry 45 (2006) 3835-3844. [PMID: 16533067]

4. Dennis, R.J., Taylor, E.J., Macauley, M.S., Stubbs, K.A., Turkenburg, J.P., Hart, S.J., Black, G.N., Vocadlo, D.J. and Davies, G.J. Structure and mechanism of a bacterial β-glucosaminidase having O-GlcNAcase activity. Nat Struct Mol Biol 13 (2006) 365-371. [PMID: 16565725]

5. Kim, E.J., Kang, D.O., Love, D.C. and Hanover, J.A. Enzymatic characterization of O-GlcNAcase isoforms using a fluorogenic GlcNAc substrate. Carbohydr. Res. 341 (2006) 971-982. [PMID: 16584714]

6. Dong, D.L. and Hart, G.W. Purification and characterization of an O-GlcNAc selective N-acetyl-β-D-glucosaminidase from rat spleen cytosol. J. Biol. Chem. 269 (1994) 19321-19330. [PMID: 8034696]

[EC 3.2.1.169 created 2011]

EC 3.2.1.170

Accepted name: mannosylglycerate hydrolase

Reaction: 2-O-(6-phospho-α-D-mannosyl)-D-glycerate + H2O = D-mannose 6-phosphate + D-glycerate

Other name(s): 2-O-(6-phospho-mannosyl)-D-glycerate hydrolase; α-mannosidase (ambiguous); mngB (gene name)

Systematic name: 2-O-(6-phospho-α-D-mannosyl)-D-glycerate acylhydrolase

Comments: The enzyme participates in the mannosylglycerate degradation pathway of some bacteria. Mannosylglycerate is phosphorylated during transport into the cell, and the phosphorylated form is hydrolysed by this enzyme.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Sampaio, M.M., Chevance, F., Dippel, R., Eppler, T., Schlegel, A., Boos, W., Lu, Y.J. and Rock, C.O. Phosphotransferase-mediated transport of the osmolyte 2-O-α-mannosyl-D-glycerate in Escherichia coli occurs by the product of the mngA (hrsA) gene and is regulated by the mngR (farR) gene product acting as repressor. J. Biol. Chem. 279 (2004) 5537-5548. [PMID: 14645248]

[EC 3.2.1.170 created 2011]

EC 3.2.1.171

Accepted name: rhamnogalacturonan hydrolase

Reaction: Endohydrolysis of α-D-GalA-(1→2)-α-L-Rha glycosidic bond in the rhamnogalacturonan I backbone with initial inversion of anomeric configuration releasing oligosaccharides with β-D-GalA at the reducing end.

For diagram of reaction click here.

Other name(s): rhamnogalacturonase A; RGase A; RG-hydrolase

Systematic name: rhamnogalacturonan α-D-GalA-(1→2)-α-L-Rha hydrolase

Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Aspergillus aculeatus.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Petersen, T.N., Kauppinen, S. and Larsen, S. The crystal structure of rhamnogalacturonase A from Aspergillus aculeatus: a right-handed parallel β helix. Structure 5 (1997) 533-544. [PMID: 9115442]

2. Kofod, L.V., Kauppinen, S., Christgau, S., Andersen, L.N., Heldt-Hansen, H.P., Dorreich, K. and Dalboge, H. Cloning and characterization of two structurally and functionally divergent rhamnogalacturonases from Aspergillus aculeatus. J. Biol. Chem. 269 (1994) 29182-29189. [PMID: 7961884]

3. Azadi, P., O'Neill, M.A., Bergmann, C., Darvill, A.G. and Albersheim, P. The backbone of the pectic polysaccharide rhamnogalacturonan I is cleaved by an endohydrolase and an endolyase. Glycobiology 5 (1995) 783-789. [PMID: 8720076]

4. Petersen, T.N., Christgau, S., Kofod, L.V., Kauppinen, S., Johnson, A.H. and Larsen, S. Crystallization and preliminary X-ray studies of rhamnogalacturonase A from Aspergillus aculeatus. Acta Crystallogr. D Biol. Crystallogr. 53 (1997) 105-107. [PMID: 15299976]

5. Pitson, S.M., Mutter, M., van den Broek, L.A., Voragen, A.G. and Beldman, G. Stereochemical course of hydrolysis catalysed by α-L-rhamnosyl and α-D-galacturonosyl hydrolases from Aspergillus aculeatus. Biochem. Biophys. Res. Commun. 242 (1998) 552-559. [PMID: 9464254]

[EC 3.2.1.171 created 2011]

EC 3.2.1.172

Accepted name: unsaturated rhamnogalacturonyl hydrolase

Reaction: 2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose + H2O = 5-dehydro-4-deoxy-D-glucuronate + L-rhamnopyranose

For diagram of reaction click here.

Glossary: 6-deoxy-2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-mannopyranose = 2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose
5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate

Other name(s): YteR; YesR

Systematic name: 2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose hydrolase

Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Bacillus subtilis strain 168.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Itoh, T., Ochiai, A., Mikami, B., Hashimoto, W. and Murata, K. A novel glycoside hydrolase family 105: the structure of family 105 unsaturated rhamnogalacturonyl hydrolase complexed with a disaccharide in comparison with family 88 enzyme complexed with the disaccharide. J. Mol. Biol. 360 (2006) 573-585. [PMID: 16781735]

2. Zhang, R., Minh, T., Lezondra, L., Korolev, S., Moy, S.F., Collart, F. and Joachimiak, A. 1.6 Å crystal structure of YteR protein from Bacillus subtilis, a predicted lyase. Proteins 60 (2005) 561-565. [PMID: 15906318]

3. Itoh, T., Ochiai, A., Mikami, B., Hashimoto, W. and Murata, K. Structure of unsaturated rhamnogalacturonyl hydrolase complexed with substrate. Biochem. Biophys. Res. Commun. 347 (2006) 1021-1029. [PMID: 16870154]

[EC 3.2.1.172 created 2011, modified 2012]

EC 3.2.1.173

Accepted name: rhamnogalacturonan galacturonohydrolase

Reaction: Exohydrolysis of the α-D-GalA-(1→2)-α-L-Rha bond in rhamnogalacturonan oligosaccharides with initial inversion of configuration releasing D-galacturonic acid from the non-reducing end of rhamnogalacturonan oligosaccharides.

For diagram of reaction click here.

Other name(s): RG-galacturonohydrolase

Systematic name: rhamnogalacturonan oligosaccharide α-D-GalA-(1→2)-α-L-Rha galacturonohydrolase

Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Aspergillus aculeatus.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Mutter, M., Beldman, G., Pitson, S.M., Schols, H.A. and Voragen, A.G. Rhamnogalacturonan α-D-galactopyranosyluronohydrolase. An enzyme that specifically removes the terminal nonreducing galacturonosyl residue in rhamnogalacturonan regions of pecti. Plant Physiol. 117 (1998) 153-163. [PMID: 9576784]

[EC 3.2.1.173 created 2011]

EC 3.2.1.174

Accepted name: rhamnogalacturonan rhamnohydrolase

Reaction: Exohydrolysis of the α-L-Rha-(1→4)-α-D-GalA bond in rhamnogalacturonan oligosaccharides with initial inversion of configuration releasing β-L-rhamnose from the non-reducing end of rhamnogalacturonan oligosaccharides.

For diagram of reaction click here.

Other name(s): RG-rhamnohydrolase; RG α-L-rhamnopyranohydrolase

Systematic name: rhamnogalacturonan oligosaccharide α-L-Rha-(1→4)-α-D-GalA rhamnohydrolase

Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Aspergillus aculeatus.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Pitson, S.M., Mutter, M., van den Broek, L.A., Voragen, A.G. and Beldman, G. Stereochemical course of hydrolysis catalysed by α-L-rhamnosyl and α-D-galacturonosyl hydrolases from Aspergillus aculeatus. Biochem. Biophys. Res. Commun. 242 (1998) 552-559. [PMID: 9464254]

2. Mutter, M., Beldman, G., Schols, H.A. and Voragen, A.G. Rhamnogalacturonan α-L-rhamnopyranohydrolase. A novel enzyme specific for the terminal nonreducing rhamnosyl unit in rhamnogalacturonan regions of pectin. Plant Physiol. 106 (1994) 241-250. [PMID: 7972516]

[EC 3.2.1.174 created 2011]

EC 3.2.1.175

Accepted name: β-D-glucopyranosyl abscisate β-glucosidase

Reaction: β-D-glucopyranosyl abscisate + H2O = β-D-glucose + abscisate

For diagram of reaction click here.

Other name(s): AtBG1; ABA-β-D-glucosidase; ABA-specific β-glucosidase; ABA-GE hydrolase; β-D-glucopyranosyl abscisate hydrolase

Systematic name: β-D-glucopyranosyl abscisate glucohydrolase

Comments: The enzyme hydrolzes the biologically inactive β-D-glucopyranosyl ester of abscisic acid to produce active abscisate. Abscisate is a phytohormone critical for plant growth, development and adaption to various stress conditions. The enzyme does not hydrolyse β-D-glucopyranosyl zeatin [1].

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Lee, K.H., Piao, H.L., Kim, H.Y., Choi, S.M., Jiang, F., Hartung, W., Hwang, I., Kwak, J.M., Lee, I.J. and Hwang, I. Activation of glucosidase via stress-induced polymerization rapidly increases active pools of abscisic acid. Cell 126 (2006) 1109-1120. [PMID: 16990135]

2. Kato-Noguchi, H. and Tanaka, Y. Effect of ABA-β-D-glucopyranosyl ester and activity of ABA-β-D-glucosidase in Arabidopsis thaliana. J. Plant Physiol. 165 (2008) 788-790. [PMID: 17923167]

3. Dietz, K.J., Sauter, A., Wichert, K., Messdaghi, D. and Hartung, W. Extracellular β-glucosidase activity in barley involved in the hydrolysis of ABA glucose conjugate in leaves. J. Exp. Bot. 51 (2000) 937-944. [PMID: 10948220]

[EC 3.2.1.175 created 2011]

EC 3.2.1.176

Accepted name: cellulose 1,4-β-cellobiosidase (reducing end)

Reaction: Hydrolysis of (1→4)-β-D-glucosidic linkages in cellulose and similar substrates, releasing cellobiose from the reducing ends of the chains.

Other name(s): CelS; CelSS; endoglucanase SS; cellulase SS; cellobiohydrolase CelS; Cel48A

Systematic name: 4-β-D-glucan cellobiohydrolase (reducing end)

Comments: Some exocellulases, most of which belong to the glycoside hydrolase family 48 (GH48, formerly known as cellulase family L), act at the reducing ends of cellulose and similar substrates. The CelS enzyme from Clostridium thermocellum is the most abundant subunit of the cellulosome formed by the organism. It liberates cellobiose units from the reducing end by hydrolysis of the glycosidic bond, employing an inverting reaction mechanism [2]. Different from EC 3.2.1.91, which attacks cellulose from the non-reducing end.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Barr, B.K., Hsieh, Y.L., Ganem, B. and Wilson, D.B. Identification of two functionally different classes of exocellulases. Biochemistry 35 (1996) 586-592. [PMID: 8555231]

2. Saharay, M., Guo, H. and Smith, J.C. Catalytic mechanism of cellulose degradation by a cellobiohydrolase, CelS. PLoS One 5 (2010) e1294. [PMID: 20967294]

[EC 3.2.1.176 created 2011]

EC 3.2.1.177

Accepted name: α-D-xyloside xylohydrolase

Reaction: Hydrolysis of terminal, non-reducing α-D-xylose residues with release of α-D-xylose.

Other name(s): α-xylosidase

Systematic name: α-D-xyloside xylohydrolase

Comments: The enzyme catalyses hydrolysis of a terminal, unsubstituted xyloside at the extreme reducing end of a xylogluco-oligosaccharide. Representative α-xylosidases from glycoside hydrolase family 31 utilize a two-step (double-displacement) mechanism involving a covalent glycosyl-enzyme intermediate, and retain the anomeric configuration of the product.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Moracci, M., Cobucci Ponzano, B., Trincone, A., Fusco, S., De Rosa, M., van Der Oost, J., Sensen, C.W., Charlebois, R.L. and Rossi, M. Identification and molecular characterization of the first α -xylosidase from an archaeon. J. Biol. Chem. 275 (2000) 22082-22089. [PMID: 10801892]

2. Sampedro, J., Sieiro, C., Revilla, G., Gonzalez-Villa, T. and Zarra, I. Cloning and expression pattern of a gene encoding an α-xylosidase active against xyloglucan oligosaccharides from Arabidopsis. Plant Physiol. 126 (2001) 910-920. [PMID: 11402218]

3. Crombie, H.J., Chengappa, S., Jarman, C., Sidebottom, C. and Reid, J.S. Molecular characterisation of a xyloglucan oligosaccharide-acting α-D-xylosidase from nasturtium (Tropaeolum majus L.) cotyledons that resembles plant 'apoplastic' α-D-glucosidases. Planta 214 (2002) 406-413. [PMID: 11859845]

4. Lovering, A.L., Lee, S.S., Kim, Y.W., Withers, S.G. and Strynadka, N.C. Mechanistic and structural analysis of a family 31 α-glycosidase and its glycosyl-enzyme intermediate. J. Biol. Chem. 280 (2005) 2105-2115. [PMID: 15501829]

5. Iglesias, N., Abelenda, J.A., Rodino, M., Sampedro, J., Revilla, G. and Zarra, I. Apoplastic glycosidases active against xyloglucan oligosaccharides of Arabidopsis thaliana. Plant Cell Physiol. 47 (2006) 55-63. [PMID: 16267099]

6. Okuyama, M., Kaneko, A., Mori, H., Chiba, S. and Kimura, A. Structural elements to convert Escherichia coli α-xylosidase (YicI) into α-glucosidase. FEBS Lett. 580 (2006) 2707-2711. [PMID: 16631751]

7. Larsbrink, J., Izumi, A., Ibatullin, F., Nakhai, A., Gilbert, H.J., Davies, G.J. and Brumer, H. Structural and enzymatic characterisation of a glycoside hydrolase family 31 α-xylosidase from Cellvibrio japonicus involved in xyloglucan saccharification. Biochem. J. 436 (2011) 567-580. [PMID: 21426303]

[EC 3.2.1.177 created 2011]

EC 3.2.1.178

Accepted name: β-porphyranase

Reaction: Hydrolysis of β-D-galactopyranose-(1→4)-α-L-galactopyranose-6-sulfate linkages in porphyran

Other name(s): porphyranase; PorA; PorB; endo-β-porphyranase

Systematic name: porphyran β-D-galactopyranose-(1→4)-α-L-galactopyranose-6-sulfate 4-glycanohydrolase

Comments: The backbone of porphyran consists largely (~70%) of (1→3)-linked β-D-galactopyranose followed by (1→4)-linked α-L-galactopyranose-6-sulfate [the other 30% are mostly agarobiose repeating units of (1→3)-linked β-D-galactopyranose followed by (1→4)-linked 3,6-anhydro-α-L-galactopyranose] [2]. This enzyme cleaves the (1→4) linkages between β-D-galactopyranose and α-L-galactopyranose-6-sulfate, forming mostly the disaccharide α-L-galactopyranose-6-sulfate-(1→3)-β-D-galactose, although some longer oligosaccharides of even number of residues are also observed. Since the enzyme is inactive on the non-sulfated agarose portion of the porphyran backbone, some agarose fragments are also included in the products [1]. Methylation of the D-galactose prevents its binding at position-1 [2].

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Hehemann, J.H., Correc, G., Barbeyron, T., Helbert, W., Czjzek, M. and Michel, G. Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota. Nature 464 (2010) 908-912. [PMID: 20376150]

2. Correc, G., Hehemann, J.H., Czjzek, M. and Helbert, W. Structural analysis of the degradation products of porphyran digested by Zobellia galactanivorans β-porphyranase A. Carbohydrate Polymers 83 (2011) 277-283.

[EC 3.2.1.178 created 2011]

EC 3.2.1.179

Accepted name: gellan tetrasaccharide unsaturated glucuronyl hydrolase

Reaction: β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp + H2O = 4-deoxy-L-threo-5-hexosulose-uronate + β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp

Other name(s): UGL (ambiguous); unsaturated glucuronyl hydrolase (ambiguous)

Systematic name: β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp β-D-4-deoxy-Δ4-GlcAp hydrolase

Comments: The enzyme releases 4-deoxy-4(5)-unsaturated D-glucuronic acid from oligosaccharides produced by polysaccharide lyases, e.g. the tetrasaccharide β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp produced by EC 4.2.2.25, gellan lyase. The enzyme can also hydrolyse unsaturated chondroitin and hyaluronate disaccharides (β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc, β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc6S, β-D-4-deoxy-Δ4-GlcAp2S-(1→3)-β-D-GalNAc, β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GlcNAc), preferring the unsulfated disaccharides to the sulfated disaccharides.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Itoh, T., Akao, S., Hashimoto, W., Mikami, B. and Murata, K. Crystal structure of unsaturated glucuronyl hydrolase, responsible for the degradation of glycosaminoglycan, from Bacillus sp. GL1 at 1.8 Å resolution. J. Biol. Chem. 279 (2004) 31804-31812. [PMID: 15148314]

2. Hashimoto, W., Kobayashi, E., Nankai, H., Sato, N., Miya, T., Kawai, S. and Murata, K. Unsaturated glucuronyl hydrolase of Bacillus sp. GL1: novel enzyme prerequisite for metabolism of unsaturated oligosaccharides produced by polysaccharide lyases. Arch. Biochem. Biophys. 368 (1999) 367-374. [PMID: 10441389]

3. Itoh, T., Hashimoto, W., Mikami, B. and Murata, K. Substrate recognition by unsaturated glucuronyl hydrolase from Bacillus sp. GL1. Biochem. Biophys. Res. Commun. 344 (2006) 253-262. [PMID: 16630576]

[EC 3.2.1.179 created 2011]

EC 3.2.1.180

Accepted name: unsaturated chondroitin disaccharide hydrolase

Reaction: β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc6S + H2O = 4-deoxy-L-threo-5-hexosulose-uronate + β-D-N-acetylgalactosamine-6-O-sulfate

Other name(s): UGL (ambiguous); unsaturated glucuronyl hydrolase (ambiguous)

Systematic name: β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc6S hydrolase

Comments: The enzyme releases 4-deoxy-4,5-didehydro D-glucuronic acid or 4-deoxy-4,5-didehydro L-iduronic acid from chondroitin disaccharides, hyaluronan disaccharides and heparin disaccharides and cleaves both glycosidic (1→3) and (1→4) bonds. It prefers the sulfated disaccharides to the unsulfated disaccharides.

Links to other databases: BRENDA, EXPASY, KEGG, CAS registry number:

References:

1. Maruyama, Y., Nakamichi, Y., Itoh, T., Mikami, B., Hashimoto, W. and Murata, K. Substrate specificity of streptococcal unsaturated glucuronyl hydrolases for sulfated glycosaminoglycan. J. Biol. Chem. 284 (2009) 18059-18069. [PMID: 19416976]

2. Nakamichi, Y., Maruyama, Y., Mikami, B., Hashimoto, W. and Murata, K. Structural determinants in streptococcal unsaturated glucuronyl hydrolase for recognition of glycosaminoglycan sulfate groups. J. Biol. Chem. 286 (2011) 6262-6271. [PMID: 21147778]

[EC 3.2.1.180 created 2011]


Continued with EC 3.2.2 and EC 3.2.3
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