Human transthyretin (TTR) complexed with Diflunisal analogues- TTR.2',4'-DICHLORO-4-HYDROXY-1,1'-BIPHENYL-3-CARBOXYLIC ACID

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.210 

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This is version 1.4 of the entry. See complete history


Diflunisal analogues stabilize the native state of transthyretin. Potent inhibition of amyloidogenesis.

Adamski-Werner, S.L.Palaninathan, S.K.Sacchettini, J.C.Kelly, J.W.

(2004) J Med Chem 47: 355-374

  • DOI: https://doi.org/10.1021/jm030347n
  • Primary Citation of Related Structures:  
    2B77, 2B9A, 2F7I, 3D2T

  • PubMed Abstract: 

    Analogues of diflunisal, an FDA-approved nonsteroidal antiinflammatory drug (NSAID), were synthesized and evaluated as inhibitors of transthyretin (TTR) aggregation, including amyloid fibril formation. High inhibitory activity was observed for 26 of the compounds. Of those, eight exhibited excellent binding selectivity for TTR in human plasma (binding stoichiometry >0.50, with a theoretical maximum of 2.0 inhibitors bound per TTR tetramer). Biophysical studies reveal that these eight inhibitors dramatically slow tetramer dissociation (the rate-determining step of amyloidogenesis) over a duration of 168 h. This appears to be achieved through ground-state stabilization, which raises the kinetic barrier for tetramer dissociation. Kinetic stabilization of WT TTR by these eight inhibitors is further substantiated by the decreasing rate of amyloid fibril formation as a function of increasing inhibitor concentration (pH 4.4). X-ray cocrystal structures of the TTR.18(2) and TTR.20(2) complexes reveal that 18 and 20 bind in opposite orientations in the TTR binding site. Moving the fluorines from the meta positions in 18 to the ortho positions in 20 reverses the binding orientation, allowing the hydrophilic aromatic ring of 20 to orient in the outer binding pocket where the carboxylate engages in favorable electrostatic interactions with the epsilon-ammonium groups of Lys 15 and 15'. The hydrophilic aryl ring of 18 occupies the inner binding pocket, with the carboxylate positioned to hydrogen bond to the serine 117 and 117' residues. Diflunisal itself appears to occupy both orientations based on the electron density in the TTR.1(2) structure. Structure-activity relationships reveal that para-carboxylate substitution on the hydrophilic ring and dihalogen substitution on the hydrophobic ring afford the most active TTR amyloid inhibitors.

  • Organizational Affiliation

    The Department of Chemistry and the Skaggs Institute of Chemical Biology, The Scripps Research Institiute, 10550 N. Torrey Pines Rd., La Jolla, California 92037, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
127Homo sapiensMutation(s): 0 
UniProt & NIH Common Fund Data Resources
Find proteins for P02766 (Homo sapiens)
Explore P02766 
Go to UniProtKB:  P02766
PHAROS:  P02766
GTEx:  ENSG00000118271 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02766
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on 3CA

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
C13 H8 Cl2 O3
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.210 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 43.215α = 90
b = 85.082β = 90
c = 64.401γ = 90
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-10-11
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Refinement description
  • Version 1.4: 2023-08-23
    Changes: Data collection, Database references, Derived calculations, Refinement description