1LGD

Crystal Structure Analysis of HCA II Mutant T199P in Complex with Bicarbonate

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.189 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history. 


Literature

Organization of an efficient carbonic anhydrase: implications for the mechanism based on structure-function studies of a T199P/C206S mutant.

Huang, S., Sjoblom, B., Sauer-Eriksson, A.E., Jonsson, B.H.

(2002) Biochemistry 41: 7628-7635

  • DOI: 10.1021/bi020053o
  • Primary Citation of Related Structures:  
    1LG5, 1LG6, 1LGD

  • PubMed Abstract: 

    • Substitution of Pro for Thr199 in the active site of human carbonic anhydrase II (HCA II)(1) reduces its catalytic efficiency about 3000-fold. X-ray crystallographic structures of the T199P/C206S variant have been determined in complex with the substrate bicarbonate and with the inhibitors thiocyanate and beta-mercaptoethanol ...

    Substitution of Pro for Thr199 in the active site of human carbonic anhydrase II (HCA II)(1) reduces its catalytic efficiency about 3000-fold. X-ray crystallographic structures of the T199P/C206S variant have been determined in complex with the substrate bicarbonate and with the inhibitors thiocyanate and beta-mercaptoethanol. The latter molecule is normally not an inhibitor of wild-type HCA II. All three ligands display novel binding interactions to the T199P/C206S mutant. The beta-mercaptoethanol molecule binds in the active site area with its sulfur atom tetrahedrally coordinated to the zinc ion. Thiocyanate binds tetrahedrally coordinated to the zinc ion in T199P/C206S, in contrast to its pentacoordinated binding to the zinc ion in wild-type HCA II. Bicarbonate binds to the mutant with two of its oxygens at the positions of the zinc water (Wat263) and Wat318 in wild-type HCA II. The environment of this area is more hydrophilic than the normal bicarbonate-binding site of HCA II situated in the hydrophobic part of the cavity normally occupied by the so-called deep water (Wat338). The observation of a new binding site for bicarbonate has implications for understanding the mechanism by which the main-chain amino group of Thr199 acquired an important role for orientation of the substrate during the evolution of the enzyme.

    Organizational Affiliation: 

    Umeå Centre for Molecular Pathogenesis, Umeå University, SE-901 87 Umeå, Sweden.



Macromolecules
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(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Carbonic anhydrase IIA260Homo 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
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00918
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN
Download Ideal Coordinates CCD File 
B [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N		 Ligand Interaction
BCT
Query on BCT
Download Ideal Coordinates CCD File 
C [auth A]BICARBONATE ION
C H O3
BVKZGUZCCUSVTD-UHFFFAOYSA-M		 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
BCT BindingDB:  1LGD Ki: min: 7.30e+7, max: 8.50e+7 (nM) from 2 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.189 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 73.012α = 90
b = 44.589β = 92.82
c = 76.636γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-07-24
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references, Derived calculations