1ESW

X-RAY STRUCTURE OF ACARBOSE BOUND TO AMYLOMALTASE FROM THERMUS AQUATICUS. IMPLICATIONS FOR THE SYNTHESIS OF LARGE CYCLIC GLUCANS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.192 

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This is version 2.0 of the entry. See complete history


Literature

X-ray structure of acarbose bound to amylomaltase from Thermus aquaticus. Implications for the synthesis of large cyclic glucans.

Przylas, I.Terada, Y.Fujii, K.Takaha, T.Saenger, W.Strater, N.

(2000) Eur J Biochem 267: 6903-6913

  • DOI: 10.1046/j.1432-1033.2000.01790.x
  • Primary Citation of Related Structures:  
    1ESW

  • PubMed Abstract: 
  • As a member of the alpha-amylase superfamily of enzymes, amylomaltase catalyzes either the transglycosylation from one alpha-1,4 glucan to another or an intramolecular cyclization. The latter reaction is typical for cyclodextrin glucanotransferases. In contrast to these enzymes, amylomaltase catalyzes the formation of cyclic glucans with a degree of polymerization larger than 22 ...

    As a member of the alpha-amylase superfamily of enzymes, amylomaltase catalyzes either the transglycosylation from one alpha-1,4 glucan to another or an intramolecular cyclization. The latter reaction is typical for cyclodextrin glucanotransferases. In contrast to these enzymes, amylomaltase catalyzes the formation of cyclic glucans with a degree of polymerization larger than 22. To characterize the factors that determine the size of the synthesized cycloamyloses, we have analyzed the X-ray structure of amylomaltase from Thermus aquaticus in complex with the inhibitor acarbose, a maltotetraose derivative, at 1.9 A resolution. Two acarbose molecules are bound to the enzyme, one in the active site groove at subsite -3 to +1 and a second one approximately 14 A away from the nonreducing end of the acarbose bound to the catalytic site. The inhibitor bound to the catalytic site occupies subsites -3 to +1. Unlike the situation in other enzymes of the alpha-amylase family, the inhibitor is not processed and the inhibitory cyclitol ring of acarbose, which mimicks the half chair conformation of the transition state, does not bind to catalytic subsite -1. The minimum ring size of cycloamyloses produced by this enzyme is proposed to be determined by the distance of the specific substrate binding sites at the active site and near Tyr54 and by the size of the 460s loop. The 250s loop might be involved in binding of the substrate at the reducing end of the scissile bond.


    Organizational Affiliation

    Institut für Chemie-Kristallographie, Freie Universität Berlin, Germany.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
AMYLOMALTASEA500Thermus aquaticusMutation(s): 0 
EC: 2.4.1.25
UniProt
Find proteins for O87172 (Thermus thermophilus)
Explore O87172 
Go to UniProtKB:  O87172
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO87172
Protein Feature View
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  • Reference Sequence
Oligosaccharides

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Entity ID: 2
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
4,6-dideoxy-4-{[(1S,4R,5S,6S)-4,5,6-trihydroxy-3-(hydroxymethyl)cyclohex-2-en-1-yl]amino}-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranoseB, C 3N/AN/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G66431MI
GlyCosmos:  G66431MI
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
EDO
Query on EDO

Download Ideal Coordinates CCD File 
D [auth A],
E [auth A]
1,2-ETHANEDIOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
Biologically Interesting Molecules (External Reference) 1 Unique
Entity ID: 2
IDChainsNameType/Class2D Diagram3D Interactions
PRD_900007
Query on PRD_900007
B, Calpha-acarboseOligosaccharide / Inhibitor Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.192 
  • Space Group: P 64
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 154α = 90
b = 154β = 90
c = 64.2γ = 120
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-04-11
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary