12CA

ALTERING THE MOUTH OF A HYDROPHOBIC POCKET. STRUCTURE AND KINETICS OF HUMAN CARBONIC ANHYDRASE II MUTANTS AT RESIDUE VAL-121


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Altering the mouth of a hydrophobic pocket. Structure and kinetics of human carbonic anhydrase II mutants at residue Val-121.

Nair, S.K.Calderone, T.L.Christianson, D.W.Fierke, C.A.

(1991) J.Biol.Chem. 266: 17320-17325


  • PubMed Abstract: 
  • Eleven amino acid substitutions at Val-121 of human carbonic anhydrase II including Gly, Ala, Ser, Leu, Ile, Lys, and Arg, were constructed by site-directed mutagenesis. This residue is at the mouth of the hydrophobic pocket in the enzyme active site ...

    Eleven amino acid substitutions at Val-121 of human carbonic anhydrase II including Gly, Ala, Ser, Leu, Ile, Lys, and Arg, were constructed by site-directed mutagenesis. This residue is at the mouth of the hydrophobic pocket in the enzyme active site. The CO2 hydrase activity and the p-nitrophenyl esterase activity of these CAII variants correlate with the hydrophobicity of the residue, suggesting that the hydrophobic character of this residue is important for catalysis. The effects of these mutations on the steady-state kinetics for CO2 hydration occur mainly in kcat/Km and Km, consistent with involvement of this residue in CO2 association. The Val-121----Ala mutant, which exhibits about one-third normal CO2 hydrase activity, has been studied by x-ray crystallographic methods. No significant changes in the mutant enzyme conformation are evident relative to the wild-type enzyme. Since Val-121 is at the mouth of the hydrophobic pocket, its substitution by the methyl side chain of alanine makes the pocket mouth significantly wider than that of the wild-type enzyme. Hence, although a moderately wide (and deep) pocket is important for substrate association, a wider mouth to this pocket does not seriously compromise the catalytic approach of CO2 toward nucleophilic zinc-bound hydroxide.


    Organizational Affiliation

    Department of Chemistry, University of Pennsylvania, Philadelphia 19104-6323.




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

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A
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
HG
Query on HG

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Download CCD File 
A
MERCURY (II) ION
Hg
BQPIGGFYSBELGY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.700α = 90.00
b = 41.700β = 104.60
c = 73.000γ = 90.00
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1992-10-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-11-29
    Type: Derived calculations, Other