4HEY

Activity Enhancers of H64A Variant of Human Carbonic Anhydrase II Possess Multiple Binding Sites within and around the Enzyme Structure

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.45 Å
  • R-Value Free: 0.184 
  • R-Value Work: 0.143 
  • R-Value Observed: 0.145 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history. 


Literature

Structural insight into activity enhancement and inhibition of H64A carbonic anhydrase II by imidazoles.

Aggarwal, M., Kondeti, B., Tu, C., Maupin, C.M., Silverman, D.N., McKenna, R.

(2014) IUCrJ 1: 129-135

  • DOI: 10.1107/S2052252514004096
  • Primary Citation of Related Structures:  
    4HEW, 4HEY, 4HEZ, 4HF3

  • PubMed Abstract: 

    • Human carbonic anhydrases (CAs) are zinc metalloenzymes that catalyze the hydration and dehydration of CO2 and HCO3 (-), respectively. The reaction follows a ping-pong mechanism, in which the rate-limiting step is the transfer of a proton from the zinc-bound solvent (OH(-)/H2O) in/out of the active site via His64, which is widely believed to be the proton-shuttling residue ...

    Human carbonic anhydrases (CAs) are zinc metalloenzymes that catalyze the hydration and dehydration of CO2 and HCO3 (-), respectively. The reaction follows a ping-pong mechanism, in which the rate-limiting step is the transfer of a proton from the zinc-bound solvent (OH(-)/H2O) in/out of the active site via His64, which is widely believed to be the proton-shuttling residue. The decreased catalytic activity (∼20-fold lower with respect to the wild type) of a variant of CA II in which His64 is replaced with Ala (H64A CA II) can be enhanced by exogenous proton donors/acceptors, usually derivatives of imidazoles and pyridines, to almost the wild-type level. X-ray crystal structures of H64A CA II in complex with four imidazole derivatives (imidazole, 1--methylimidazole, 2--methylimidazole and 4-methylimidazole) have been determined and reveal multiple binding sites. Two of these imidazole binding sites have been identified that mimic the positions of the 'in' and 'out' rotamers of His64 in wild-type CA II, while another directly inhibits catalysis by displacing the zinc-bound solvent. The data presented here not only corroborate the importance of the imidazole side chain of His64 in proton transfer during CA catalysis, but also provide a complete structural understanding of the mechanism by which imidazoles enhance (and inhibit when used at higher concentrations) the activity of H64A CA II.

    Organizational Affiliation: 

    Department of Biochemistry and Molecular Biology, University of Florida , PO Box 100245, Gainesville, FL 32610, USA.



Macromolecules
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(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Carbonic anhydrase 2A260Homo sapiensMutation(s): 1 
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
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.45 Å
  • R-Value Free: 0.184 
  • R-Value Work: 0.143 
  • R-Value Observed: 0.145 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 42.418α = 90
b = 41.334β = 104.44
c = 71.958γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PHENIXrefinement
PDB_EXTRACTdata extraction
ADSCdata collection
HKL-2000data reduction
PHENIXphasing

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-10-23
    Type: Initial release
  • Version 1.1: 2014-03-12
    Changes: Database references
  • Version 1.2: 2014-08-20
    Changes: Database references
  • Version 1.3: 2017-11-15
    Changes: Refinement description