3MNK

Human Carbonic Anhydrase II Mutant K170H


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.150 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural and kinetic study of the extended active site for proton transfer in human carbonic anhydrase II.

Domsic, J.F.Williams, W.Fisher, S.Z.Tu, C.Agbandje-McKenna, M.Silverman, D.N.McKenna, R.

(2010) Biochemistry 49: 6394-6399

  • DOI: 10.1021/bi1007645
  • Primary Citation of Related Structures:  3MNH, 3MNI, 3MNJ

  • PubMed Abstract: 
  • The catalysis of CO(2) hydration by human carbonic anhydrase II (HCA II) is limited in maximal velocity by proton transfer from a zinc-bound water molecule to the proton shuttle His64. This proton transfer occurs along a hydrogen-bonded water network ...

    The catalysis of CO(2) hydration by human carbonic anhydrase II (HCA II) is limited in maximal velocity by proton transfer from a zinc-bound water molecule to the proton shuttle His64. This proton transfer occurs along a hydrogen-bonded water network, leading to the proton shuttle residue His64, which in turn transfers the proton to bulk solvent. The side chain of His64 occupies two conformations in wild-type HCA II, pointing inward toward the zinc or outward toward bulk solvent. Previously, several studies have examined the roles of residues of the active site cavity that interact with the solvent-mediated hydrogen-bonded network between His64 and the zinc-bound water. Here these studies are extended to examine the effects on proton transfer by mutation at Lys170 (to Ala, Asp, Glu, and His), a residue located near the side chain of His64 but over 15 A away from the active site zinc. In all four variants, His64 is observed in the inward conformation associated with a decrease in the pK(a) of His64 by as much as 1.0 unit and an increase in the rate constant for proton transfer to as much as 4 micros(-1), approximately 5-fold larger than wild-type HCA II. The results show a significant extension of the effective active site of HCA II from the zinc-bound water at the base of the conical cavity in the enzyme to Lys170 near the rim of the cavity. These data emphasize that the active site of HCA II is extended to include residues that, at first glance, appear to be too far from the zinc to exert any catalytic effects.


    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 2
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
NA
Query on NA

Download SDF File 
Download CCD File 
A
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.150 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.716α = 90.00
b = 41.562β = 104.53
c = 72.772γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
CCP4model building
CCP4phasing
SCALEPACKdata scaling
CrystalCleardata collection
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-07-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance