2QHN | pdb_00002qhn

Crystal Structure of Chek1 in Complex with Inhibitor 1a

• PDB DOI: https://doi.org/10.2210/pdb2QHN/pdb

• Classification: TRANSFERASE
• Organism(s): Homo sapiens
• Expression System: Spodoptera frugiperda
• Mutation(s): No 


• Deposited: 2007-07-02 Released: 2008-03-18 
• Deposition Author(s): Yan, Y., Munshi, S.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.70 Å
• R-Value Free: 
  0.230 (Depositor) 
• R-Value Work: 
  0.202 (Depositor) 
• R-Value Observed: 
  0.203 (Depositor) 

Starting Model: experimental

Literature

Optimization of a pyrazoloquinolinone class of Chk1 kinase inhibitors.

Brnardic, E.J., Garbaccio, R.M., Fraley, M.E., Tasber, E.S., Steen, J.T., Arrington, K.L., Dudkin, V.Y., Hartman, G.D., Stirdivant, S.M., Drakas, B.A., Rickert, K., Walsh, E.S., Hamilton, K., Buser, C.A., Hardwick, J., Tao, W., Beck, S.C., Mao, X., Lobell, R.B., Sepp-Lorenzino, L., Yan, Y., Ikuta, M., Munshi, S.K., Kuo, L.C., Kreatsoulas, C.

(2007) Bioorg Med Chem Lett 17: 5989-5994

• PubMed: 17804227 
• DOI: https://doi.org/10.1016/j.bmcl.2007.07.051
• Primary Citation Related Structures: 
  2QHM, 2QHN


• PubMed Abstract: 
  

  The development of 2,5-dihydro-4H-pyrazolo[4,3-c]quinolin-4-ones as inhibitors of Chk1 kinase is described. Introduction of a fused ring at the C7/C8 positions of the pyrazoloquinolinone provided an increase in potency while guidance from overlapping inhibitor bound Chk1 X-ray crystal structures contributed to the discovery of a potent and solubilizing propyl amine moiety in compound 52 (Chk1 IC(50)=3.1 nM).

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Organizational Affiliation: 
• Department of Medicinal Chemistry, Merck Research Laboratories, West Point, PA 19486, USA. [e-mail]

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content 

• Total Structure Weight: 37.15 kDa 
• Atom Count: 2,425 
• Modeled Residue Count: 268 
• Deposited Residue Count: 323 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Serine/threonine-protein kinase Chk1	A	323	Homo sapiens	Mutation(s): 0  EC: 2.7.11.1
UniProt & NIH Common Fund Data Resources
Find proteins for O14757 (Homo sapiens) Explore O14757  Go to UniProtKB:  O14757
PHAROS:  O14757 GTEx:  ENSG00000149554

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
582	B [auth A]	5-ETHYL-3-METHYL-1,5-DIHYDRO-4H-PYRAZOLO[4,3-C]QUINOLIN-4-ONE C13 H13 N3 O ASEHARDUZDZEKS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.70 Å
• R-Value Free:  0.230 (Depositor) 
• R-Value Work:  0.202 (Depositor) 
• R-Value Observed: 0.203 (Depositor) 

Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 45.14	α = 90
b = 65.68	β = 94.55
c = 58.23	γ = 90

Software Package:

Software Name	Purpose
BUSTER-TNT	refinement
CrystalClear	data collection
d*TREK	data reduction
d*TREK	data scaling
CNS	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 2008-03-18 
Deposition Author(s): Yan, Y., Munshi, S.

Revision History  

• Version 1.0: 2008-03-18
  Type: Initial release
  
• Version 1.1: 2011-07-13
  Changes: Version format compliance
• Version 1.2: 2023-08-30
  Changes: Data collection, Database references, Derived calculations, Refinement description