1NQ9

Crystal Structure of Antithrombin in the Pentasaccharide-Bound Intermediate State


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.209 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Crystal Structure of Antithrombin in a Heparin-Bound Intermediate State

Johnson, D.J.D.Huntington, J.A.

(2003) Biochemistry 42: 8712-8719

  • DOI: 10.1021/bi034524y

  • PubMed Abstract: 
  • Antithrombin is activated as an inhibitor of the coagulation proteases through its specific interaction with a heparin pentasaccharide. The binding of heparin induces a global conformational change in antithrombin which results in the freeing of its ...

    Antithrombin is activated as an inhibitor of the coagulation proteases through its specific interaction with a heparin pentasaccharide. The binding of heparin induces a global conformational change in antithrombin which results in the freeing of its reactive center loop for interaction with target proteases and a 1000-fold increase in heparin affinity. The allosteric mechanism by which the properties of antithrombin are altered by its interactions with the specific pentasaccharide sequence of heparin is of great interest to the medical and protein biochemistry communities. Heparin binding has previously been characterized as a two-step, three-state mechanism where, after an initial weak interaction, antithrombin undergoes a conformational change to its high-affinity state. Although the native and heparin-activated states have been determined through protein crystallography, the number and magnitude of conformational changes render problematic the task of determining which account for the improved heparin affinity and how the heparin binding region is linked to the expulsion of the reactive center loop. Here we present the structure of an intermediate pentasaccharide-bound conformation of antithrombin which has undergone all of the conformational changes associated with activation except loop expulsion and helix D elongation. We conclude that the basis of the high-affinity state is not improved interaction with the pentasaccharide but a lowering of the global free energy due to conformational changes elsewhere in antithrombin. We suggest a mechanism in which the role of helix D elongation is to lock antithrombin in the five-stranded fully activated conformation.


    Organizational Affiliation

    Department of Haematology, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Antithrombin-III
I, L
432Homo sapiensMutation(s): 0 
Gene Names: SERPINC1 (AT3)
Find proteins for P01008 (Homo sapiens)
Go to Gene View: SERPINC1
Go to UniProtKB:  P01008
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NTP
Query on NTP

Download SDF File 
Download CCD File 
I, L
HEPARIN PENTASACCHARIDE
C36 H60 O55 S9
MQLWHPBUPXUQHM-XAYBSJBFSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
I, L
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.6 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.209 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 69.679α = 90.00
b = 86.760β = 109.54
c = 96.921γ = 90.00
Software Package:
Software NamePurpose
Adxvdata processing
SCALAdata scaling
MOLREPphasing
CCP4data scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-09-30
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Non-polymer description, Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description