Crystal structure of spleen tyrosine kinase complexed with 6-((1R,2S)-2-Amino-cyclohexylamino)-4-(6-ethyl-pyridin-2-ylamino)-pyridazine-3-carboxylic acid amide

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.200 
  • R-Value Observed: 0.202 

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Ligand Structure Quality Assessment 

This is version 1.2 of the entry. See complete history


Using ovality to predict nonmutagenic, orally efficacious pyridazine amides as cell specific spleen tyrosine kinase inhibitors.

Lucas, M.C.Bhagirath, N.Chiao, E.Goldstein, D.M.Hermann, J.C.Hsu, P.Y.Kirchner, S.Kennedy-Smith, J.J.Kuglstatter, A.Lukacs, C.Menke, J.Niu, L.Padilla, F.Peng, Y.Polonchuk, L.Railkar, A.Slade, M.Soth, M.Xu, D.Yadava, P.Yee, C.Zhou, M.Liao, C.

(2014) J Med Chem 57: 2683-2691

  • DOI: https://doi.org/10.1021/jm401982j
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Inhibition of spleen tyrosine kinase has attracted much attention as a mechanism for the treatment of cancers and autoimmune diseases such as asthma, rheumatoid arthritis, and systemic lupus erythematous. We report the structure-guided optimization of pyridazine amide spleen tyrosine kinase inhibitors. Early representatives of this scaffold were highly potent and selective but mutagenic in an Ames assay. An approach that led to the successful identification of nonmutagenic examples, as well as further optimization to compounds with reduced cardiovascular liabilities is described. Select pharmacokinetic and in vivo efficacy data are presented.

  • Organizational Affiliation

    Hoffmann-La Roche Inc., pRED, Pharma Research & Early Development, Small Molecule Research, 340 Kingsland Street, Nutley, New Jersey 07110, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Tyrosine-protein kinase SYK291Homo sapiensMutation(s): 0 
Gene Names: SYK
UniProt & NIH Common Fund Data Resources
Find proteins for P43405 (Homo sapiens)
Explore P43405 
Go to UniProtKB:  P43405
PHAROS:  P43405
GTEx:  ENSG00000165025 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP43405
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on 0VH

Download Ideal Coordinates CCD File 
B [auth A]6-{[(1R,2S)-2-aminocyclohexyl]amino}-4-[(6-ethylpyridin-2-yl)amino]pyridazine-3-carboxamide
C18 H25 N7 O
Binding Affinity Annotations 
IDSourceBinding Affinity
0VH BindingDB:  4FZ7 IC50: min: 3.2, max: 79 (nM) from 2 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.200 
  • R-Value Observed: 0.202 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 39.63α = 90
b = 84.977β = 90
c = 88.607γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-07-10
    Type: Initial release
  • Version 1.1: 2019-07-17
    Changes: Data collection, Database references, Refinement description
  • Version 1.2: 2023-09-13
    Changes: Data collection, Database references, Derived calculations, Refinement description