2NNG

Structure of inhibitor binding to Carbonic Anhydrase II

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.20 Å
  • R-Value Free: 0.165 
  • R-Value Observed: 0.132 

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This is version 1.4 of the entry. See complete history. 


Literature

Structural Analysis of Charge Discrimination in the Binding of Inhibitors to Human Carbonic Anhydrases I and II.

Srivastava, D.K., Jude, K.M., Banerjee, A.L., Haldar, M., Manokaran, S., Kooren, J., Mallik, S., Christianson, D.W.

(2007) J Am Chem Soc 129: 5528-5537

  • DOI: 10.1021/ja068359w
  • Primary Citation of Related Structures:  
    2NMX, 2NN1, 2NN7, 2NNG, 2NNO, 2NNS, 2NNV

  • PubMed Abstract: 

    • Despite the similarity in the active site pockets of carbonic anhydrase (CA) isozymes I and II, the binding affinities of benzenesulfonamide inhibitors are invariably higher with CA II as compared to CA I. To explore the structural basis of this molecular recognition phenomenon, we have designed and synthesized simple benzenesulfonamide inhibitors substituted at the para position with positively charged, negatively charged, and neutral functional groups, and we have determined the affinities and X-ray crystal structures of their enzyme complexes ...

    Despite the similarity in the active site pockets of carbonic anhydrase (CA) isozymes I and II, the binding affinities of benzenesulfonamide inhibitors are invariably higher with CA II as compared to CA I. To explore the structural basis of this molecular recognition phenomenon, we have designed and synthesized simple benzenesulfonamide inhibitors substituted at the para position with positively charged, negatively charged, and neutral functional groups, and we have determined the affinities and X-ray crystal structures of their enzyme complexes. The para-substituents are designed to bind in the midsection of the 15 A deep active site cleft, where interactions with enzyme residues and solvent molecules are possible. We find that a para-substituted positively charged amino group is more poorly tolerated in the active site of CA I compared with CA II. In contrast, a para-substituted negatively charged carboxylate substituent is tolerated equally well in the active sites of both CA isozymes. Notably, enzyme-inhibitor affinity increases upon neutralization of inhibitor charged groups by amidation or esterification. These results inform the design of short molecular linkers connecting the benzenesulfonamide group and a para-substituted tail group in "two-prong" CA inhibitors: an optimal linker segment will be electronically neutral, yet capable of engaging in at least some hydrogen bond interactions with protein residues and/or solvent. Microcalorimetric data reveal that inhibitor binding to CA I is enthalpically less favorable and entropically more favorable than inhibitor binding to CA II. This contrasting behavior may arise in part from differences in active site desolvation and the conformational entropy of inhibitor binding to each isozyme active site.

    Organizational Affiliation: 

    Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota 58105, USA. dk.srivastava@ndsu.nodak.edu



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Carbonic anhydrase 2A260Homo sapiensMutation(s): 0 
Gene Names: CA2
EC: 4.2.1.1
UniProt & NIH Common Fund Data Resources
Find proteins for P00918 (Homo sapiens)
Explore P00918 
Go to UniProtKB:  P00918
PHAROS:  P00918
GTEx:  ENSG00000104267 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00918
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZYX
Query on ZYX
Download Ideal Coordinates CCD File 
C [auth A]4-(2-AMINOETHYL)BENZENESULFONAMIDE
C8 H12 N2 O2 S
FXNSVEQMUYPYJS-UHFFFAOYSA-N		 Ligand Interaction
GOL
Query on GOL
Download Ideal Coordinates CCD File 
D [auth A]GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N		 Ligand Interaction
ZN
Query on ZN
Download Ideal Coordinates CCD File 
B [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N		 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CMH
Query on CMH		A L-PEPTIDE LINKINGC4 H9 Hg N O2 SCYS
Binding Affinity Annotations 
IDSourceBinding Affinity
ZYX BindingDB:  2NNG Ki: min: 37, max: 1.60e+5 (nM) from 6 assay(s)
IC50: 3100 (nM) from 1 assay(s)
PDBBind:  2NNG Kd: 4400 (nM) from 1 assay(s)
Binding MOAD:  2NNG Kd: 4400 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.20 Å
  • R-Value Free: 0.165 
  • R-Value Observed: 0.132 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 42.289α = 90
b = 41.44β = 104.56
c = 71.975γ = 90
Software Package:
Software NamePurpose
SHELXL-97refinement
SCALEPACKdata scaling
CNSrefinement
PDB_EXTRACTdata extraction
Blu-Icedata collection
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing
DENZOdata reduction

Structure Validation

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Ligand Structure Quality Assessment 


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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-05-08
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.3: 2017-10-18
    Changes: Refinement description
  • Version 1.4: 2019-07-24
    Changes: Data collection, Derived calculations, Refinement description