3DVB

X-ray crystal structure of mutant N62V human Carbonic Anhydrase II


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.184 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Role of hydrophilic residues in proton transfer during catalysis by human carbonic anhydrase II.

Zheng, J.Avvaru, B.S.Tu, C.McKenna, R.Silverman, D.N.

(2008) Biochemistry 47: 12028-12036

  • DOI: 10.1021/bi801473w
  • Primary Citation of Related Structures:  3DV7, 3DVC, 3DVD

  • PubMed Abstract: 
  • Catalysis by the zinc metalloenzyme human carbonic anhydrase II (HCA II) is limited in maximal velocity by proton transfer between His64 and the zinc-bound solvent molecule. Asn62 extends into the active site cavity of HCA II adjacent to His64 and ha ...

    Catalysis by the zinc metalloenzyme human carbonic anhydrase II (HCA II) is limited in maximal velocity by proton transfer between His64 and the zinc-bound solvent molecule. Asn62 extends into the active site cavity of HCA II adjacent to His64 and has been shown to be one of several hydrophilic residues participating in a hydrogen-bonded solvent network within the active site. We compared several site-specific mutants of HCA II with replacements at position 62 (Ala, Val, Leu, Thr, and Asp). The efficiency of catalysis in the hydration of CO 2 for the resulting mutants has been characterized by (18)O exchange, and the structures of the mutants have been determined by X-ray crystallography to 1.5-1.7 A resolution. Each of these mutants maintained the ordered water structure observed by X-ray crystallography in the active site cavity of wild-type HCA II; hence, this water structure was not a variable in comparing with wild type the activities of mutants at residue 62. Crystal structures of wild-type and N62T HCA II showed both an inward and outward orientation of the side chain of His64; however, other mutants in this study showed predominantly inward (N62A, N62V, N62L) or predominantly outward (N62D) orientations of His64. A significant role of Asn62 in HCA II is to permit two conformations of the side chain of His64, the inward and outward, that contributes to maximal efficiency of proton transfer between the active site and solution. The site-specific mutant N62D had a mainly outward orientation of His64, yet the difference in p K a between the proton donor His64 and zinc-bound hydroxide was near zero, as in wild-type HCA II. The rate of proton transfer in catalysis by N62D HCA II was 5% that of wild type, showing that His64 mainly in the outward orientation is associated with inefficient proton transfer compared with His64 in wild type which shows both inward and outward orientations. These results emphasize the roles of the residues of the hydrophilic side of the active site cavity in maintaining efficient catalysis by carbonic anhydrase.


    Organizational Affiliation

    Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida 32610, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Carbonic anhydrase 2
A
259Homo 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 1 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
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.197 
  • R-Value Work: 0.184 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.795α = 90.00
b = 41.696β = 104.64
c = 72.927γ = 90.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
CNSrefinement
CNSphasing
CrystalCleardata collection
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2008-07-18 
  • Released Date: 2008-11-11 
  • Deposition Author(s): Avvaru, B.S.

Revision History 

  • Version 1.0: 2008-11-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance