DB code: S00208

RLCP classification 1.30.35885.972 : Hydrolysis
CATH domain : TIM Barrel Catalytic domain
CSA 1cz1
M-CSA 1cz1

CATH domain Related DB codes (homologues) : TIM Barrel S00202 S00210 S00748 S00906 S00907 S00911 S00912 S00915 M00134 M00160 D00479 S00204 S00205 S00206 S00207 S00203 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 RefSeq CAZy Pfam
P29717 Glucan 1,3-beta-glucosidase
XP_721488.1 (Protein)
XM_716395.1 (DNA/RNA sequence)
GH5 (Glycoside Hydrolase Family 5)
PF00150 (Cellulase)
[Graphical View]

KEGG enzyme name
glucan 1,3-beta-glucosidase
beta-1,3-glucan exo-hydrolase
exo (1->3)-glucanohydrolase
1,3-beta-glucan glucohydrolase

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
P29717 EXG_CANAL Successive hydrolysis of beta-D-glucose units from the non-reducing ends of (1->3)-beta-D-glucans, releasing alpha-glucose. Monomer. Secreted.

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

Compound table
Substrates Products Intermediates
KEGG-id C00965 C00001 C02048 C00965 C00267 I00119
Compound 1,3-beta-D-Glucan H2O Laminaribiose 1,3-beta-D-Glucan alpha-D-Glucose Peptidyl-Glu-1,3-beta-D-glucan Transition state in deglycosylation
Type polysaccharide H2O polysaccharide polysaccharide carbohydrate
ChEBI 15377
PubChem 22247451
1cz1A Unbound Unbound Unbound Unbound Unbound Unbound
1eqcA Unbound Unbound Unbound Unbound Unbound Transition-state-analogue:CTS
1eqpA Unbound Unbound Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.
Swiss-prot;P29717 (see [Comments])

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1cz1A ARG 92;ASN 191;GLU 192;HIS 253;TYR 255;GLU 292
1eqcA ARG 92;ASN 191;GLU 192;HIS 253;TYR 255;GLU 292
1eqpA ARG 92;ASN 191;GLU 192;HIS 253;TYR 255;GLU 292

References for Catalytic Mechanism
References Sections No. of steps in catalysis
Scheme 1 4
Fig.2, p.648-649 4
Fig.1, p.779-780

Comments crystallization, diffraction (1.9 angstroms)
Medline ID
PubMed ID 1583691
Journal J Mol Biol
Year 1992
Volume 225
Pages 217-8
Authors Cutfield S, Brooke G, Sullivan P, Cutfield J
Title Crystallization of the exo(1,3)-beta-glucanase from Candida albicans.
Related PDB
Related UniProtKB
Comments Active site glu-330.
Medline ID 97166150
PubMed ID 9013549
Journal J Biol Chem
Year 1997
Volume 272
Pages 3161-7
Authors MacKenzie LF, Brooke GS, Cutfield JF, Sullivan PA, Withers SG
Title Identification of Glu-330 as the catalytic nucleophile of Candida albicans exo-beta-(1,3)-glucanase.
Related PDB
Related UniProtKB P29717
Comments Review
Medline ID
PubMed ID 9345622
Journal Curr Opin Struct Biol
Year 1997
Volume 7
Pages 645-51
Authors White A, Rose DR
Title Mechanism of catalysis by retaining beta-glycosyl hydrolases.
Related PDB
Related UniProtKB
Comments X-ray crystallography (1.85 angstroms) of 45-438.
Medline ID 20079533
PubMed ID 10610795
Journal J Mol Biol
Year 1999
Volume 294
Pages 771-83
Authors Cutfield SM, Davies GJ, Murshudov G, Anderson BF, Moody PC, Sullivan PA, Cutfield JF
Title The structure of the exo-beta-(1,3)-glucanase from Candida albicans in native and bound forms: relationship between a pocket and groove in family 5 glycosyl hydrolases.
Related PDB 1cz1 1eqc
Related UniProtKB P29717
Comments crystal structure
Medline ID
PubMed ID 11112513
Journal Protein Eng
Year 2000
Volume 13
Pages 735-8
Authors Cutfield JF, Sullivan PA, Cutfield SM
Title Minor Structural Consequences of the Alternative Cug Codon Usage (Ser for Leu) in Candida Albicans Exoglucanase.
Related PDB 1eqp
Related UniProtKB

This enzyme belongs to the glycosidase family-5.
The paper [3] described general aspects of the catalytic mechanism of retaining beta-glycosyl hydrolases. Accoriding to the paper, the mechanism can be described as follows:
(1) Saccharide binds in a "twisted-boat" conformation.
(2) The beta-1,4 linkage is broken, leading to the formation of a transition state with a slight positive charge at the anomeric carbon, in a "half-chair" conformation, which develops a oxocarbenium-ion-like character.
(3) An approach of the ionic species to the catalytic nucleophile leads to the formation of a covalent intermediate of inverted alpha-configuration in a so-called chair conformation. The aglycon is released and a water molecule diffuses into the vicinity of the acidic residue as a general base.
(4) The covalent intermediate reactivates through an oxocarbenium-ion-like transition state. The general base abstracts a proton from the incoming water, which in turn carries out a nucleophilic attack on the C1 atom of the residual saccharide.
Moreover, comparing the structural data with that of xylanase (E.C. (D00479 in EzCatDB) and the other family-5 enzyme, cellulase (E.C. (S00203 in EzCatDB), Tyr255 might stabilize the leaving nucleophile, Glu292 in deglycosylation, whilst His253 might modulate the activity of Glu192. On the other hand, Tyr255 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 2012-02-14