Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Work: 0.164 
  • R-Value Observed: 0.164 

wwPDB Validation 3D Report Full Report

This is version 1.2 of the entry. See complete history


Reversal of the hydrogen bond to zinc ligand histidine-119 dramatically diminishes catalysis and enhances metal equilibration kinetics in carbonic anhydrase II.

Huang, C.C.Lesburg, C.A.Kiefer, L.L.Fierke, C.A.Christianson, D.W.

(1996) Biochemistry 35: 3439-3446

  • DOI: 10.1021/bi9526692
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Direct metal ligands to transition metals in metalloproteins exert a profound effect on protein-metal affinity and function. Indirect ligands, i.e., second-shell residues that hydrogen bond to direct metal ligands, typically exert more subtle effects ...

    Direct metal ligands to transition metals in metalloproteins exert a profound effect on protein-metal affinity and function. Indirect ligands, i.e., second-shell residues that hydrogen bond to direct metal ligands, typically exert more subtle effects on the chemical properties of the protein-metal complex. However, E117 of human carbonic anhydrase II (CAII), which is part of the E117-119-Zn(2+) triad, is a notable exception: E117-substituted CAIIs exhibit dramatically increased kinetics of zinc complexation, and the E117Q variant exhibits enormously diminished catalytic activity and sulfonamide affinity. The three-dimensional structures of zinc-bound and zinc-free E117Q CAII reveal no discrete structural changes in the active site that are responsible for enhanced zinc equilibration kinetics and decreased activity. Additionally, the structure of the acetazolamide complex is essentially identical to that of the wild-type enzyme despite the 10(4)-fold loss of enzyme-inhibitor affinity. We conclude, therefore, that the functional differences between E117Q and wild-type CAIIs arise from electrostatic and not structural differences in the active site. We propose that the E117Q substitution reverses the polarity of the residue 117-H119 hydrogen bond, thereby stabilizing H119 as a histidinate anion in the E117Q CAII holoenzyme. The additional negative charge in the first coordination sphere of the metal ion increases the pK(a) of the zinc-water ligand, destabilizes the transition state for CO(2) hydration, and facilitates the exchange of a zinc-histidine ligand with an additional water molecule by decreasing the stability of the tetrahedral zinc complex. These novel properties engineered into E117Q CAII facilitate the exploitation of CAII as a rapid and sensitive Zn(2+) biosensor.

    Organizational Affiliation

    Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.


Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
259Homo sapiensMutation(s): 1 
Gene Names: CA2
Find proteins for P00918 (Homo sapiens)
Go to UniProtKB:  P00918
NIH Common Fund Data Resources
PHAROS  P00918
Protein Feature View
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
Query on AZM

Download CCD File 
C4 H6 N4 O3 S2
 Ligand Interaction
Query on ZN

Download CCD File 
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
AZMIC50:  48.29999923706055   nM  BindingDB
AZMKd:  0.07000000029802322   nM  BindingDB
AZMKd:  17   nM  BindingDB
AZMIC50:  68.5999984741211   nM  BindingDB
AZMKd:  2.5999999046325684   nM  BindingDB
AZMKd:  250000000   nM  Binding MOAD
AZMKd:  18   nM  BindingDB
AZMKi:  10.100000381469727   nM  BindingDB
AZMIC50:  16.200000762939453   nM  BindingDB
AZMIC50:  34.29999923706055   nM  BindingDB
AZMKd:  10   nM  BindingDB
AZMIC50:  89.9000015258789   nM  BindingDB
AZMIC50:  48.900001525878906   nM  BindingDB
AZMKd:  0.05999999865889549   nM  BindingDB
AZMIC50:  60.400001525878906   nM  BindingDB
AZMIC50:  2400   nM  BindingDB
AZMIC50:  98.30000305175781   nM  BindingDB
AZMIC50:  2800   nM  BindingDB
AZMIC50:  77.80000305175781   nM  BindingDB
AZMKi:  15   nM  BindingDB
AZMIC50:  3800   nM  BindingDB
AZMIC50:  3900   nM  BindingDB
AZMKi:  18   nM  BindingDB
AZMKd:  1.5   nM  BindingDB
AZMIC50:  4100   nM  BindingDB
AZMIC50:  4020   nM  BindingDB
AZMIC50:  4500   nM  BindingDB
AZMKi:  22   nM  BindingDB
AZMIC50:  4300   nM  BindingDB
AZMKi:  7   nM  BindingDB
AZMKi:  10   nM  BindingDB
AZMKi:  12   nM  BindingDB
AZMKi:  11   nM  BindingDB
AZMKi:  40.810001373291016   nM  BindingDB
AZMIC50:  8.880000114440918   nM  BindingDB
AZMKd :  250000000   nM  PDBBind
AZMIC50:  152   nM  BindingDB
AZMKi:  250   nM  BindingDB
AZMIC50:  220   nM  BindingDB
AZMKi:  370   nM  BindingDB
AZMKi:  374   nM  BindingDB
AZMIC50:  283   nM  BindingDB
AZMIC50:  285   nM  BindingDB
AZMKi:  4.900000095367432   nM  BindingDB
AZMIC50:  8.899999618530273   nM  BindingDB
AZMKi:  104   nM  BindingDB
AZMIC50:  6.699999809265137   nM  BindingDB
AZMIC50:  92.5   nM  BindingDB
AZMKi:  159   nM  BindingDB
AZMKi:  184   nM  BindingDB
AZMIC50:  124   nM  BindingDB
AZMIC50:  69.69999694824219   nM  BindingDB
AZMKi:  12.300000190734863   nM  BindingDB
AZMKi:  61   nM  BindingDB
AZMIC50:  47.599998474121094   nM  BindingDB
AZMIC50:  48.099998474121094   nM  BindingDB
AZMKi:  25   nM  BindingDB
AZMIC50:  53.099998474121094   nM  BindingDB
AZMIC50:  309   nM  BindingDB
AZMKi:  25   nM  BindingDB
AZMIC50:  351   nM  BindingDB
AZMKi:  33   nM  BindingDB
AZMIC50:  362   nM  BindingDB
AZMIC50:  370   nM  BindingDB
AZMIC50:  440   nM  BindingDB
AZMIC50:  441   nM  BindingDB
AZMIC50:  10   nM  BindingDB
AZMKi:  3300   nM  BindingDB
AZMIC50:  12   nM  BindingDB
AZMIC50:  13   nM  BindingDB
AZMIC50:  14   nM  BindingDB
AZMKi:  3.299999952316284   nM  BindingDB
AZMIC50:  15   nM  BindingDB
AZMKd:  6.800000190734863   nM  BindingDB
AZMIC50:  18.5   nM  BindingDB
AZMKi:  2000   nM  BindingDB
AZMIC50:  6   nM  BindingDB
AZMKi:  2100   nM  BindingDB
AZMKi:  2150   nM  BindingDB
AZMKi:  0.3400000035762787   nM  BindingDB
AZMIC50:  38   nM  BindingDB
AZMIC50:  56.5   nM  BindingDB
AZMIC50:  63   nM  BindingDB
AZMIC50:  0.47999998927116394   nM  BindingDB
AZMIC50:  68   nM  BindingDB
AZMIC50:  20   nM  BindingDB
AZMKi:  420   nM  BindingDB
AZMIC50:  24   nM  BindingDB
AZMIC50:  23   nM  BindingDB
AZMIC50:  110.27999877929688   nM  BindingDB
AZMIC50:  25   nM  BindingDB
AZMIC50:  28   nM  BindingDB
AZMKd:  46   nM  BindingDB
AZMKi:  0.800000011920929   nM  BindingDB
AZMIC50:  29   nM  BindingDB
AZMKd:  38   nM  BindingDB
AZMIC50:  36   nM  BindingDB
AZMIC50:  37   nM  BindingDB
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Work: 0.164 
  • R-Value Observed: 0.164 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 42.7α = 90
b = 41.7β = 104.6
c = 73γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
MOSFLMdata reduction

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1996-07-11
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance