1CPU

SUBSITE MAPPING OF THE ACTIVE SITE OF HUMAN PANCREATIC ALPHA-AMYLASE USING SUBSTRATES, THE PHARMACOLOGICAL INHIBITOR ACARBOSE, AND AN ACTIVE SITE VARIANT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.170 
  • R-Value Observed: 0.170 

wwPDB Validation   3D Report Full Report


This is version 3.0 of the entry. See complete history


Literature

Subsite mapping of the human pancreatic alpha-amylase active site through structural, kinetic, and mutagenesis techniques.

Brayer, G.D.Sidhu, G.Maurus, R.Rydberg, E.H.Braun, C.Wang, Y.Nguyen, N.T.Overall, C.M.Withers, S.G.

(2000) Biochemistry 39: 4778-4791

  • DOI: 10.1021/bi9921182
  • Primary Citation of Related Structures:  
    1CPU, 2CPU, 3CPU

  • PubMed Abstract: 
  • We report a multifaceted study of the active site region of human pancreatic alpha-amylase. Through a series of novel kinetic analyses using malto-oligosaccharides and malto-oligosaccharyl fluorides, an overall cleavage action pattern for this enzyme has been developed ...

    We report a multifaceted study of the active site region of human pancreatic alpha-amylase. Through a series of novel kinetic analyses using malto-oligosaccharides and malto-oligosaccharyl fluorides, an overall cleavage action pattern for this enzyme has been developed. The preferred binding/cleavage mode occurs when a maltose residue serves as the leaving group (aglycone sites +1 and +2) and there are three sugars in the glycon (-1, -2, -3) sites. Overall it appears that five binding subsites span the active site, although an additional glycon subsite appears to be a significant factor in the binding of longer substrates. Kinetic parameters for the cleavage of substrates modified at the 2 and 4' ' positions also highlight the importance of these hydroxyl groups for catalysis and identify the rate-determining step. Further kinetic and structural studies pinpoint Asp197 as being the likely nucleophile in catalysis, with substitution of this residue leading to an approximately 10(6)-fold drop in catalytic activity. Structural studies show that the original pseudo-tetrasaccharide structure of acarbose is modified upon binding, presumably through a series of hydrolysis and transglycosylation reactions. The end result is a pseudo-pentasaccharide moiety that spans the active site region with its N-linked "glycosidic" bond positioned at the normal site of cleavage. Interestingly, the side chains of Glu233 and Asp300, along with a water molecule, are aligned about the inhibitor N-linked glycosidic bond in a manner suggesting that these might act individually or collectively in the role of acid/base catalyst in the reaction mechanism. Indeed, kinetic analyses show that substitution of the side chains of either Glu233 or Asp300 leads to as much as a approximately 10(3)-fold decrease in catalytic activity. Structural analyses of the Asp300Asn variant of human pancreatic alpha-amylase and its complex with acarbose clearly demonstrate the importance of Asp300 to the mode of inhibitor binding.


    Organizational Affiliation

    Department of Biochemistry, University of British Columbia, Vancouver V6T 1Z3, Canada. brayer@laue.biochem.ubc.ca



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PROTEIN (ALPHA-AMYLASE)A496Homo sapiensMutation(s): 0 
Gene Names: AMY2A
EC: 3.2.1.1
UniProt & NIH Common Fund Data Resources
Find proteins for P04746 (Homo sapiens)
Explore P04746 
Go to UniProtKB:  P04746
PHAROS:  P04746
Protein Feature View
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  • Reference Sequence
Oligosaccharides

Help

Entity ID: 2
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
4-amino-4,6-dideoxy-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranoseB2N/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G90989WB
GlyCosmos:  G90989WB
Entity ID: 3
MoleculeChainsChain Length2D DiagramGlycosylation3D Interactions
alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranoseC2N/A Oligosaccharides Interaction
Glycosylation Resources
GlyTouCan:  G07411ON
GlyCosmos:  G07411ON
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NAG (Subject of Investigation/LOI)
Query on NAG

Download Ideal Coordinates CCD File 
D [auth A]2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
HMC (Subject of Investigation/LOI)
Query on HMC

Download Ideal Coordinates CCD File 
G [auth A]5-HYDROXYMETHYL-CHONDURITOL
C7 H12 O5
PJPGMULJEYSZBS-VZFHVOOUSA-N
 Ligand Interaction
CA
Query on CA

Download Ideal Coordinates CCD File 
E [auth A]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
CL
Query on CL

Download Ideal Coordinates CCD File 
F [auth A]CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
PCA
Query on PCA
AL-PEPTIDE LINKINGC5 H7 N O3GLN
Biologically Interesting Molecules (External Reference) 1 Unique
Entity ID: 3
IDChainsNameType/Class2D Diagram3D Interactions
PRD_900001
Query on PRD_900001
Calpha-maltoseOligosaccharide /  Nutrient Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.170 
  • R-Value Observed: 0.170 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 52.91α = 90
b = 68.9β = 90
c = 131.77γ = 90
Software Package:
Software NamePurpose
X-PLORrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-06-14
    Type: Initial release
  • Version 1.1: 2008-04-26
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 2.0: 2019-12-25
    Changes: Data collection, Database references, Derived calculations, Polymer sequence
  • Version 3.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary