5IKV

The Structure of Flufenamic Acid Bound to Human Cyclooxygenase-2


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.187 

wwPDB Validation   3D Report Full Report


This is version 2.0 of the entry. See complete history


Literature

Substrate-selective Inhibition of Cyclooxygeanse-2 by Fenamic Acid Derivatives Is Dependent on Peroxide Tone.

Orlando, B.J.Malkowski, M.G.

(2016) J Biol Chem 291: 15069-15081

  • DOI: 10.1074/jbc.M116.725713
  • Primary Citation of Related Structures:  
    5IKR, 5IKQ, 5IKT, 5IKV

  • PubMed Abstract: 
  • Cyclooxygenase-2 (COX-2) catalyzes the oxygenation of arachidonic acid (AA) and endocannabinoid substrates, placing the enzyme at a unique junction between the eicosanoid and endocannabinoid signaling pathways. COX-2 is a sequence homodimer, but the enzyme displays half-of-site reactivity, such that only one monomer of the dimer is active at a given time ...

    Cyclooxygenase-2 (COX-2) catalyzes the oxygenation of arachidonic acid (AA) and endocannabinoid substrates, placing the enzyme at a unique junction between the eicosanoid and endocannabinoid signaling pathways. COX-2 is a sequence homodimer, but the enzyme displays half-of-site reactivity, such that only one monomer of the dimer is active at a given time. Certain rapid reversible, competitive nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to inhibit COX-2 in a substrate-selective manner, with the binding of inhibitor to a single monomer sufficient to inhibit the oxygenation of endocannabinoids but not arachidonic acid. The underlying mechanism responsible for substrate-selective inhibition has remained elusive. We utilized structural and biophysical methods to evaluate flufenamic acid, meclofenamic acid, mefenamic acid, and tolfenamic acid for their ability to act as substrate-selective inhibitors. Crystal structures of each drug in complex with human COX-2 revealed that the inhibitor binds within the cyclooxygenase channel in an inverted orientation, with the carboxylate group interacting with Tyr-385 and Ser-530 at the top of the channel. Tryptophan fluorescence quenching, continuous-wave electron spin resonance, and UV-visible spectroscopy demonstrate that flufenamic acid, mefenamic acid, and tolfenamic acid are substrate-selective inhibitors that bind rapidly to COX-2, quench tyrosyl radicals, and reduce higher oxidation states of the heme moiety. Substrate-selective inhibition was attenuated by the addition of the lipid peroxide 15-hydroperoxyeicosatertaenoic acid. Collectively, these studies implicate peroxide tone as an important mechanistic component of substrate-selective inhibition by flufenamic acid, mefenamic acid, and tolfenamic acid.


    Organizational Affiliation

    From the Department of Structural Biology, The State University of New York at Buffalo and the Hauptman-Woodward Medical Research Institute, Buffalo, New York 14203 mgm22@buffalo.edu.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Prostaglandin G/H synthase 2A, B551Homo sapiensMutation(s): 0 
Gene Names: PTGS2COX2
EC: 1.14.99.1
Find proteins for P35354 (Homo sapiens)
Explore P35354 
Go to UniProtKB:  P35354
NIH Common Fund Data Resources
PHAROS:  P35354
Protein Feature View
Expand
  • Reference Sequence
Oligosaccharides

Help

Entity ID: 2
MoleculeChainsChain Length2D Diagram Glycosylation3D Interactions
alpha-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranoseC, D3 N-Glycosylation Oligosaccharides Interaction
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
COH
Query on COH

Download Ideal Coordinates CCD File 
F [auth A], O [auth B]PROTOPORPHYRIN IX CONTAINING CO
C34 H32 Co N4 O4
AQTFKGDWFRRIHR-CTESUSPADG
 Ligand Interaction
BOG
Query on BOG

Download Ideal Coordinates CCD File 
M [auth A]octyl beta-D-glucopyranoside
C14 H28 O6
HEGSGKPQLMEBJL-RKQHYHRCSA-N
 Ligand Interaction
FLF
Query on FLF

Download Ideal Coordinates CCD File 
E [auth A], N [auth B]2-[[3-(TRIFLUOROMETHYL)PHENYL]AMINO] BENZOIC ACID
C14 H10 F3 N O2
LPEPZBJOKDYZAD-UHFFFAOYSA-N
 Ligand Interaction
NAG
Query on NAG

Download Ideal Coordinates CCD File 
G [auth A], P [auth B]2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
NH4
Query on NH4

Download Ideal Coordinates CCD File 
H [auth A] , I [auth A] , J [auth A] , K [auth A] , L [auth A] , Q [auth B] , R [auth B] , S [auth B] , 
H [auth A],  I [auth A],  J [auth A],  K [auth A],  L [auth A],  Q [auth B],  R [auth B],  S [auth B],  T [auth B]
AMMONIUM ION
H4 N
QGZKDVFQNNGYKY-UHFFFAOYSA-O
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.51 Å
  • R-Value Free: 0.224 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.187 
  • Space Group: I 2 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 126.918α = 90
b = 149.334β = 90
c = 184.766γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

View Full Validation Report



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United StatesGM115386

Revision History  (Full details and data files)

  • Version 1.0: 2016-05-25
    Type: Initial release
  • Version 1.1: 2016-06-08
    Changes: Data collection, Database references
  • Version 1.2: 2016-07-27
    Changes: Database references
  • Version 1.3: 2017-09-27
    Changes: Advisory, Author supporting evidence, Database references, Derived calculations
  • Version 1.4: 2019-12-25
    Changes: Author supporting evidence
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary