DB code: S00207

RLCP classification 1.30.36210.971 : Hydrolysis
CATH domain : TIM Barrel Catalytic domain
CSA 1ghs
M-CSA 1ghs

CATH domain Related DB codes (homologues) : TIM Barrel S00202 S00210 S00748 S00906 S00907 S00911 S00912 S00915 M00134 M00160 D00479 S00204 S00205 S00206 S00203 S00208 S00209 S00211 S00213 S00214 M00113 T00307 D00165 D00166 D00169 D00176 D00501 D00502 D00503 D00844 D00861 D00864 M00026 M00112 M00193 M00346 T00057 T00062 T00063 T00066 T00067

Uniprot Enzyme Name
UniprotKB Protein name Synonyms CAZy Pfam
P15737 Glucan endo-1,3-beta-glucosidase GII
EC ((1->3)-beta-glucan endohydrolase GII
1->3)-beta-glucan endohydrolase GII) ((1->3)-beta-glucanase isoenzyme GII
Beta-1,3-endoglucanase GII
GH17 (Glycoside Hydrolase Family 17)
PF00332 (Glyco_hydro_17)
[Graphical View]

KEGG enzyme name
glucan endo-1,3-beta-D-glucosidase
1,3-beta-D-glucan 3-glucanohydrolase
(1->3)-beta-glucan 3-glucanohydrolase
1,3-beta-D-glucan glucanohydrolase

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
P15737 E13B_HORVU Hydrolysis of (1->3)-beta-D-glucosidic linkages in (1->3)-beta-D-glucans.

KEGG Pathways
Map code Pathways E.C.
MAP00500 Starch and sucrose metabolism

Compound table
Substrates Products Intermediates
KEGG-id C00965 C00001 C00771 C00965
Compound 1,3-beta-D-Glucan H2O Laminarin 1,3-beta-D-Glucan
Type polysaccharide H2O polysaccharide polysaccharide
ChEBI 15377
PubChem 962
1ghsA Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound
1ghsB Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1ghsA Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain GLU 94;TYR 168;GLU 231
1ghsB Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain GLU 94;TYR 168;GLU 231

References for Catalytic Mechanism
References Sections No. of steps in catalysis
p.115, Scheme1 2
Fig.3 4

Comments crystallization, preliminary X-ray analysis (1.8 angstroms)
Medline ID
PubMed ID 8254681
Journal J Mol Biol
Year 1993
Volume 234
Pages 888-9
Authors Chen L, Garrett TJ, Varghese JN, Fincher GB, Hoj PB
Title Crystallization and preliminary X-ray analysis of (1,3)- and (1,3;1,4)-beta-D-glucanases from germinating barley.
Related PDB
Related UniProtKB
Comments catalytic amino acid residues
Medline ID
PubMed ID 8514770
Journal J Biol Chem
Year 1993
Volume 268
Pages 13318-26
Authors Chen L, Fincher GB, Hoj PB
Title Evolution of polysaccharide hydrolase substrate specificity. Catalytic amino acids are conserved in barley 1,3-1,4- and 1,3-beta-glucanases.
Related PDB
Related UniProtKB
Comments X-ray crystallography (2.3 angstroms).
Medline ID 94195828
PubMed ID 8146192
Journal Proc Natl Acad Sci USA
Year 1994
Volume 91
Pages 2785-9
Authors Varghese JN, Garrett TPJ, Colman PM, Chen L, Hoej PB, Fincher GB
Title Three-dimensional structures of two plant beta-glucan endohydrolases with distinct substrate specificities.
Related PDB 1ghs
Related UniProtKB P15737
Medline ID
PubMed ID 7729513
Journal FEBS Lett
Year 1995
Volume 362
Pages 281-5
Authors Jenkins J, Lo Leggio L, Harris G, Pickersgill R
Title Beta-glucosidase, beta-galactosidase, family A cellulases, family F xylanases and two barley glycanases form a superfamily of enzymes with 8-fold beta/alpha architecture and with two conserved glutamates near the carboxy-terminal ends of beta-strands four and seven.
Related PDB
Related UniProtKB
Medline ID
PubMed ID 7492591
Journal Biochim Biophys Acta
Year 1995
Volume 1253
Pages 112-6
Authors Chen L, Sadek M, Stone BA, Brownlee RT, Fincher GB, Hoj PB
Title Stereochemical course of glucan hydrolysis by barley (1-->3)- and (1-->3, 1-->4)-beta-glucanases.
Related PDB
Related UniProtKB
Comments structure-function relationships (review)
Medline ID
PubMed ID 11554481
Journal Plant Mol Biol
Year 2001
Volume 47
Pages 73-91
Authors Hrmova M, Fincher GB
Title Structure-function relationships of beta-D-glucan endo- and exohydrolases from higher plants.
Related PDB
Related UniProtKB
Medline ID
PubMed ID 12023973
Journal J Biol Chem
Year 2002
Volume 277
Pages 30102-11
Authors Hrmova M, Imai T, Rutten SJ, Fairweather JK, Pelosi L, Bulone V, Driguez H, Fincher GB
Title Mutated varley (1,3)-beta-D-glucan endohydrolases synthesize crystalline (1,3)-beta-D-glucans.
Related PDB
Related UniProtKB

This enzyme belongs to the family-17 of glycosidase enzymes, a member family of 4/7 superfamily, which has got the catalytic residues at the C-terminal ends of beta-4 and beta-7 on the (alpha/beta)8 barrel fold.
Glu231 has been reported to be the nucleophilic residue of this enzyme (see [2]). In contrast, whilst the paper [2] indicated experimentally that Glu288 might be a general acid that protonates the glycosidic oxygen during hydrolysis, another paper [4] suggested that Glu94, which is conserved among family-1, 2, 5, 10 and 17, might play a role as the general acid.
On the other hand, It is not clear which type of mechanisms is adopted by this enzyme, SN1 like mechanism or SN2-like reaction. The paper [5] suggested an SN2 mechanism, in which Glu231 serve as a nucleophile, attacking the anomeric carbon to generate a covalent-bonded intermediate.
Moreover, whether this enzyme adopts a retention mechanism, or an inversion one, is still unknown [6].
However, considering the other family-17 enzyme, Lichenase (E.C. (S00209 in EzCatDB), the mechanism must be similar to that. Furthermore, comparing the structural data with that of xylanase (E.C. (D00479 in EzCatDB), Tyr168 might stabilize the leaving nucleophile, Glu231 in deglycosylation. On the other hand, Tyr168 might modulate the activity of the nucleophile, according to the data of the other homologous enzyme, beta-glucosidase (E.C. (S00205 in EzCatDB).

Created Updated
2003-02-03 2009-02-26