3TON

Crystral Structure of the C-terminal Subunit of Human Maltase-Glucoamylase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.953 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.232 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Structural insight into substrate specificity of human intestinal maltase-glucoamylase

Ren, L.M.Qin, X.H.Cao, X.F.Wang, L.L.Bai, F.Bai, G.Shen, Y.

(2011) Protein Cell 2: 827-836

  • DOI: 10.1007/s13238-011-1105-3
  • Primary Citation of Related Structures:  3TOP

  • PubMed Abstract: 
  • Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- ...

    Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alpha-glucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.


    Organizational Affiliation

    State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Maltase-glucoamylase, intestinal
A, B
908Homo sapiensGene Names: MGAM (MGA, MGAML)
EC: 3.2.1.3, 3.2.1.20
Find proteins for O43451 (Homo sapiens)
Go to Gene View: MGAM
Go to UniProtKB:  O43451
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.953 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.232 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 106.232α = 90.00
b = 106.232β = 90.00
c = 517.557γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
HKL-2000data collection
PHENIXrefinement
HKL-2000data scaling
PHASESphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-11-23
    Type: Initial release