Crystal structure of alpha-glucosidase

Experimental Data Snapshot

  • Resolution: 2.15 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.182 
  • R-Value Observed: 0.184 

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This is version 1.3 of the entry. See complete history


Structural analysis of the alpha-glucosidase HaG provides new insights into substrate specificity and catalytic mechanism

Shen, X.Saburi, W.Gai, Z.Kato, K.Ojima-Kato, T.Yu, J.Komoda, K.Kido, Y.Matsui, H.Mori, H.Yao, M.

(2015) Acta Crystallogr D Biol Crystallogr 71: 1382-1391

  • DOI: https://doi.org/10.1107/S139900471500721X
  • Primary Citation of Related Structures:  
    3WY1, 3WY2, 3WY3, 3WY4

  • PubMed Abstract: 

    α-Glucosidases, which catalyze the hydrolysis of the α-glucosidic linkage at the nonreducing end of the substrate, are important for the metabolism of α-glucosides. Halomonas sp. H11 α-glucosidase (HaG), belonging to glycoside hydrolase family 13 (GH13), only has high hydrolytic activity towards the α-(1 → 4)-linked disaccharide maltose among naturally occurring substrates. Although several three-dimensional structures of GH13 members have been solved, the disaccharide specificity and α-(1 → 4) recognition mechanism of α-glucosidase are unclear owing to a lack of corresponding substrate-bound structures. In this study, four crystal structures of HaG were solved: the apo form, the glucosyl-enzyme intermediate complex, the E271Q mutant in complex with its natural substrate maltose and a complex of the D202N mutant with D-glucose and glycerol. These structures explicitly provide insights into the substrate specificity and catalytic mechanism of HaG. A peculiar long β → α loop 4 which exists in α-glucosidase is responsible for the strict recognition of disaccharides owing to steric hindrance. Two residues, Thr203 and Phe297, assisted with Gly228, were found to determine the glycosidic linkage specificity of the substrate at subsite +1. Furthermore, an explanation of the α-glucosidase reaction mechanism is proposed based on the glucosyl-enzyme intermediate structure.

  • Organizational Affiliation

    School of Light Industry and Food Science, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou, Guangdong 510640, People's Republic of China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
538Halomonas sp. H11Mutation(s): 0 
Gene Names: aglA
Find proteins for H3K096 (Halomonas sp. H11)
Explore H3K096 
Go to UniProtKB:  H3K096
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupH3K096
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.15 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.182 
  • R-Value Observed: 0.184 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.54α = 90
b = 119.59β = 90
c = 177.97γ = 90
Software Package:
Software NamePurpose
SERGUIdata collection
XDSdata reduction
XDSdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2015-06-10
    Type: Initial release
  • Version 1.1: 2017-11-22
    Changes: Refinement description
  • Version 1.2: 2018-03-21
    Changes: Database references
  • Version 1.3: 2023-11-08
    Changes: Data collection, Database references, Derived calculations, Refinement description