1YO0

Proton Transfer from His200 in Human Carbonic Anhydrase II


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.187 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Proton transfer in a Thr200His mutant of human carbonic anhydrase II

Bhatt, D.Tu, C.Fisher, S.Z.Hernandez Prada, J.A.McKenna, R.Silverman, D.N.

(2005) Proteins 61: 239-245

  • DOI: 10.1002/prot.20615
  • Primary Citation of Related Structures:  
    1YO2, 1YO1, 1YO0

  • PubMed Abstract: 
  • Human carbonic anhydrase II (HCA II) has a histidine at position 64 (His64) that donates a proton to the zinc-bound hydroxide in catalysis of the dehydration of bicarbonate. To examine the effect of the histidine location on proton shuttling, His64 was replaced with Ala and Thr200 replaced with histidine (H64A-T200H HCAII), effectively relocating the proton shuttle residue 2 A closer to the zinc-bound hydroxide compared to wild type HCA II ...

    Human carbonic anhydrase II (HCA II) has a histidine at position 64 (His64) that donates a proton to the zinc-bound hydroxide in catalysis of the dehydration of bicarbonate. To examine the effect of the histidine location on proton shuttling, His64 was replaced with Ala and Thr200 replaced with histidine (H64A-T200H HCAII), effectively relocating the proton shuttle residue 2 A closer to the zinc-bound hydroxide compared to wild type HCA II. The crystal structure of H64A-T200H HCA II at 1.8 A resolution shows the side chain of His200 directly hydrogen-bonded with the zinc-bound solvent. Different proton transfer processes were observed at pH 6 and at pH 8 during the catalytic hydration-dehydration cycle, measured by mass spectrometry as the depletion of 18O from C18O2 by H64A-T200H HCA II. The process at pH 6.0 is attributed to proton transfer between the side chain of His200 and the zinc-bound hydroxide, in analogy with proton transfer involving His64 in wild-type HCA II. At pH 8.0 it is attributed to proton transfer between bicarbonate and the zinc-bound hydroxide, as supported by the dependence of the rate of proton transfer on bicarbonate concentration and on solvent hydrogen isotope effects. This study establishes that a histidine directly hydrogen-bonded to the zinc-bound hydroxide, can adopt the correct distance geometry to support proton transfer


    Organizational Affiliation

    Department of Pharmacology and Therapeutics University of Florida, Gainesville, Florida 32610-0245, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Carbonic anhydrase IIA260Homo sapiensMutation(s): 2 
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
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download Ideal Coordinates CCD File 
B [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
CL
Query on CL

Download Ideal Coordinates CCD File 
C [auth A]CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
CL BindingDB:  1YO0 Ki: min: 2.00e+8, max: 2.00e+8 (nM) from 2 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.187 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 42.673α = 90
b = 41.459β = 104.75
c = 72.769γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling
CNSrefinement
CNSphasing

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-09-20
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Refinement description