3MNH

Human Carbonic Anhydrase II Mutant K170A


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.188 
  • R-Value Work: 0.155 
  • R-Value Observed: 0.156 

wwPDB Validation   3D Report Full Report


This is version 1.3 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: https://doi.org/10.1021/bi1007645
  • Primary Citation of Related Structures:  
    3MNH, 3MNI, 3MNJ, 3MNK

  • 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, 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:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Carbonic anhydrase 2260Homo sapiensMutation(s): 1 
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
GTEx:  ENSG00000104267 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00918
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.188 
  • R-Value Work: 0.155 
  • R-Value Observed: 0.156 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 42.645α = 90
b = 41.564β = 104.5
c = 72.75γ = 90
Software Package:
Software NamePurpose
CrystalCleardata collection
CCP4model building
REFMACrefinement
HKL-2000data reduction
SCALEPACKdata scaling
CCP4phasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-07-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-06
    Changes: Database references, Derived calculations
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description