1G0E

SITE-SPECIFIC MUTANT (HIS64 REPLACED WITH ALA) OF HUMAN CARBONIC ANHYDRASE II COMPLEXED WITH 4-METHYLIMIDAZOLE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.179 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structural and kinetic analysis of the chemical rescue of the proton transfer function of carbonic anhydrase II.

Duda, D.Tu, C.Qian, M.Laipis, P.Agbandje-McKenna, M.Silverman, D.N.McKenna, R.

(2001) Biochemistry 40: 1741-1748

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Histidine 64 in human carbonic anhydrase II (HCA II) functions in the catalytic pathway of CO(2) hydration as a shuttle to transfer protons between the zinc-bound water and bulk water. Catalysis of the exchange of (18)O between CO(2) and water, measu ...

    Histidine 64 in human carbonic anhydrase II (HCA II) functions in the catalytic pathway of CO(2) hydration as a shuttle to transfer protons between the zinc-bound water and bulk water. Catalysis of the exchange of (18)O between CO(2) and water, measured by mass spectrometry, is dependent on this proton transfer and was decreased more than 10-fold for H64A HCA II compared with wild-type HCA II. The loss of catalytic activity of H64A HCA II could be rescued by 4-methylimidazole (4-MI), an exogenous proton donor, in a saturable process with a maximum activity of 40% of wild-type HCA II. The crystal structure of the rescued complex at 1.6 A resolution shows 4-MI bound in the active-site cavity of H64A HCA II, through pi stacking interactions with Trp 5 and H-bonding interactions with water molecules. In this location, 4-MI is about 12 A from the zinc and approximates the observed "out" position of His 64 in the structure of the wild-type enzyme. 4-MI appears to compensate for the absence of His 64 and rescues the catalytic activity of the H64A HCA II mutant. This result strongly suggests that the out conformation of His 64 is effective in the transfer of protons between the zinc-bound solvent molecule and solution.


    Related Citations: 
    • Structure of Native and Apo Carbonic Anhydrase II and Structure of Some of its Anion-ligand Complexes.
      Hakansson, K.,Carlsson, M.,Svensson, L.A.,Liljas, A.
      (1992) J.Mol.Biol. 227: 1192


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CARBONIC ANHYDRASE II
A
260Homo sapiensMutations: A64H
Gene Names: CA2
EC: 4.2.1.1
Find proteins for P00918 (Homo sapiens)
Go to Gene View: CA2
Go to UniProtKB:  P00918
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
A
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
4MZ
Query on 4MZ

Download SDF File 
Download CCD File 
A
4-METHYLIMIDAZOLE
C4 H6 N2
XLSZMDLNRCVEIJ-UHFFFAOYSA-N
 Ligand Interaction
HG
Query on HG

Download SDF File 
Download CCD File 
A
MERCURY (II) ION
Hg
BQPIGGFYSBELGY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.179 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.142α = 90.00
b = 41.490β = 104.28
c = 72.063γ = 90.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
CNSphasing
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2000-10-06 
  • Released Date: 2000-10-18 
  • Deposition Author(s): Duda, D., McKenna, R.

Revision History 

  • Version 1.0: 2000-10-18
    Type: Initial release
  • Version 1.1: 2007-10-16
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-04
    Type: Refinement description