1TG3

Effect of Shuttle Location and pH Environment on H+ Transfer in Human Carbonic Anhydrase II


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.171 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structural and Kinetic Characterization of Active-Site Histidine as a Proton Shuttle in Catalysis by Human Carbonic Anhydrase II

Fisher, Z.Hernandez Prada, J.A.Tu, C.K.Duda, D.Yoshioka, C.An, H.Govindasamy, L.Silverman, D.N.McKenna, R.

(2005) Biochemistry 44: 1097-1105

  • DOI: 10.1021/bi0480279
  • Primary Citation of Related Structures:  1T9N, 1TB0, 1TBT, 1TE3, 1TEQ, 1TEU, 1TG9, 1TH9, 1THK

  • PubMed Abstract: 
  • In the catalysis of the hydration of carbon dioxide and dehydration of bicarbonate by human carbonic anhydrase II (HCA II), a histidine residue (His64) shuttles protons between the zinc-bound solvent molecule and the bulk solution. To evaluate the ef ...

    In the catalysis of the hydration of carbon dioxide and dehydration of bicarbonate by human carbonic anhydrase II (HCA II), a histidine residue (His64) shuttles protons between the zinc-bound solvent molecule and the bulk solution. To evaluate the effect of the position of the shuttle histidine and pH on proton shuttling, we have examined the catalysis and crystal structures of wild-type HCA II and two double mutants: H64A/N62H and H64A/N67H HCA II. His62 and His67 both have their side chains extending into the active-site cavity with distances from the zinc approximately equivalent to that of His64. Crystal structures were determined at pH 5.1-10.0, and the catalysis of the exchange of (18)O between CO(2) and water was assessed by mass spectrometry. Efficient proton shuttle exceeding a rate of 10(5) s(-)(1) was observed for histidine at positions 64 and 67; in contrast, relatively inefficient proton transfer at a rate near 10(3) s(-)(1) was observed for His62. The observation, in the crystal structures, of a completed hydrogen-bonded water chain between the histidine shuttle residue and the zinc-bound solvent does not appear to be required for efficient proton transfer. The data suggest that the number of intervening water molecules between the donor and acceptor supporting efficient proton transfer in HCA II is important, and furthermore suggest that a water bridge consisting of two intervening water molecules is consistent with efficient proton transfer.


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Carbonic anhydrase II
A
260Homo sapiensGene 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 2 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
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
SO4Ki: 89000000 - >300000000 nM (99) BINDINGDB
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.171 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.839α = 90.00
b = 41.629β = 104.75
c = 72.949γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
SCALEPACKdata scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-01-25
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description