1HNY

The structure of human pancreatic alpha-amylase at 1.8 angstroms resolution and comparisons with related enzymes


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Work: 0.174 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The structure of human pancreatic alpha-amylase at 1.8 A resolution and comparisons with related enzymes.

Brayer, G.D.Luo, Y.Withers, S.G.

(1995) Protein Sci. 4: 1730-1742

  • DOI: 10.1002/pro.5560040908

  • PubMed Abstract: 
  • The structure of human pancreatic alpha-amylase has been determined to 1.8 A resolution using X-ray diffraction techniques. This enzyme is found to be composed of three structural domains. The largest is Domain A (residues 1-99, 169-404), which forms ...

    The structure of human pancreatic alpha-amylase has been determined to 1.8 A resolution using X-ray diffraction techniques. This enzyme is found to be composed of three structural domains. The largest is Domain A (residues 1-99, 169-404), which forms a central eight-stranded parallel beta-barrel, to one end of which are located the active site residues Asp 197, Glu 233, and Asp 300. Also found in this vicinity is a bound chloride ion that forms ligand interactions to Arg 195, Asn 298, and Arg 337. Domain B is the smallest (residues 100-168) and serves to form a calcium binding site against the wall of the beta-barrel of Domain A. Protein groups making ligand interactions to this calcium include Asn 100, Arg 158, Asp 167, and His 201. Domain C (residues 405-496) is made up of anti-parallel beta-structure and is only loosely associated with Domains A and B. It is notable that the N-terminal glutamine residue of human pancreatic alpha-amylase undergoes a posttranslational modification to form a stable pyrrolidone derivative that may provide protection against other digestive enzymes. Structure-based comparisons of human pancreatic alpha-amylase with functionally related enzymes serve to emphasize three points. Firstly, despite this approach facilitating primary sequence alignments with respect to the numerous insertions and deletions present, overall there is only approximately 15% sequence homology between the mammalian and fungal alpha-amylases. Secondly, in contrast, these same studies indicate that significant structural homology is present and of the order of approximately 70%. Thirdly, the positioning of Domain C can vary considerably between alpha-amylases. In terms of the more closely related porcine enzyme, there are four regions of polypeptide chain (residues 237-250, 304-310, 346-354, and 458-461) with significantly different conformations from those in human pancreatic alpha-amylase. At least two of these could play a role in observed differential substrate and cleavage pattern specificities between these enzymes. Similarly, amino acid differences between human pancreatic and salivary alpha-amylases have been localized and a number of these occur in the vicinity of the active site.


    Related Citations: 
    • Isolation, Crystallization and Preliminary Diffraction Analyses of Human Pancreatic Alpha-Amylase
      Burk, D.,Wang, Y.,Dombroski, D.,Berghuis, A.M.,Evans, S.V.,Luo, Y.,Withers, S.G.,Brayer, G.D.
      (1993) J.Mol.Biol. 230: 1084


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HUMAN PANCREATIC ALPHA-AMYLASE
A
496Homo sapiensMutation(s): 0 
Gene Names: AMY2A
EC: 3.2.1.1
Find proteins for P04746 (Homo sapiens)
Go to Gene View: AMY2A
Go to UniProtKB:  P04746
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CL
Query on CL

Download SDF File 
Download CCD File 
A
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
PCA
Query on PCA
A
L-PEPTIDE LINKINGC5 H7 N O3GLU
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Work: 0.174 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 53.040α = 90.00
b = 74.800β = 90.00
c = 137.340γ = 90.00
Software Package:
Software NamePurpose
MSCdata collection
X-PLORphasing
MSCdata reduction
X-PLORrefinement
X-PLORmodel building
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 1995-06-28 
  • Released Date: 1996-03-08 
  • Deposition Author(s): Luo, Y., Brayer, G.D.

Revision History 

  • Version 1.0: 1996-03-08
    Type: Initial release
  • Version 1.1: 2008-03-03
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance