1SMA

CRYSTAL STRUCTURE OF A MALTOGENIC AMYLASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.209 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structure of a maltogenic amylase provides insights into a catalytic versatility.

Kim, J.S.Cha, S.S.Kim, H.J.Kim, T.J.Ha, N.C.Oh, S.T.Cho, H.S.Cho, M.J.Kim, M.J.Lee, H.S.Kim, J.W.Choi, K.Y.Park, K.H.Oh, B.H.

(1999) J.Biol.Chem. 274: 26279-26286


  • PubMed Abstract: 
  • Amylases catalyze the hydrolysis of starch material and play central roles in carbohydrate metabolism. Compared with many different amylases that are able to hydrolyze only alpha-D-(1,4)-glycosidic bonds, maltogenic amylases exhibit catalytic versati ...

    Amylases catalyze the hydrolysis of starch material and play central roles in carbohydrate metabolism. Compared with many different amylases that are able to hydrolyze only alpha-D-(1,4)-glycosidic bonds, maltogenic amylases exhibit catalytic versatility: hydrolysis of alpha-D-(1,4)- and alpha-D-(1,6)-glycosidic bonds and transglycosylation of oligosaccharides to C3-, C4-, or C6-hydroxyl groups of various acceptor mono- or disaccharides. It has been speculated that the catalytic property of the enzymes is linked to the additional approximately 130 residues at the N terminus that are absent in other typical alpha-amylases. The crystal structure of a maltogenic amylase from a Thermus strain was determined at 2.8 A. The structure, an analytical centrifugation, and a size exclusion column chromatography proved that the enzyme is a dimer in solution. The N-terminal segment of the enzyme folds into a distinct domain and comprises the enzyme active site together with the central (alpha/beta)(8) barrel of the adjacent subunit. The active site is a narrow and deep cleft suitable for binding cyclodextrins, which are the preferred substrates to other starch materials. At the bottom of the active site cleft, an extra space, absent in the other typical alpha-amylases, is present whose size is comparable with that of a disaccharide. The space is most likely to host an acceptor molecule for the transglycosylation and to allow binding of a branched oligosaccharide for hydrolysis of alpha-D-(1,4)-glycosidic or alpha-D-(1,6)-glycosidic bond. The (alpha/beta)(8) barrel of the enzyme is the preserved scaffold in all the known amylases. The structure represents a novel example of how an enzyme acquires a different substrate profile and a catalytic versatility from a common active site and represents a framework for explaining the catalytic activities of transglycosylation and hydrolysis of alpha-D-(1,6)-glycosidic bond.


    Organizational Affiliation

    Department of Life Science, and School of Environmental Engineering, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, South Korea.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MALTOGENIC AMYLASE
A, B
588Thermus sp. IM6501Mutation(s): 0 
Find proteins for O69007 (Thermus sp. IM6501)
Go to UniProtKB:  O69007
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.267 
  • R-Value Work: 0.209 
  • Space Group: P 61
Unit Cell:
Length (Å)Angle (°)
a = 118.370α = 90.00
b = 118.370β = 90.00
c = 266.700γ = 120.00
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORphasing
X-PLORrefinement
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-04-26
    Type: Initial release
  • Version 1.1: 2008-04-26
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance