1CIM

THE POSITIONS OF HIS-64 AND A BOUND WATER IN HUMAN CARBONIC ANHYDRASE II UPON BINDING THREE STRUCTURALLY RELATED INHIBITORS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Positions of His-64 and a bound water in human carbonic anhydrase II upon binding three structurally related inhibitors.

Smith, G.M.Alexander, R.S.Christianson, D.W.McKeever, B.M.Ponticello, G.S.Springer, J.P.Randall, W.C.Baldwin, J.J.Habecker, C.N.

(1994) Protein Sci. 3: 118-125

  • DOI: 10.1002/pro.5560030115
  • Primary Citation of Related Structures:  1CIL, 1CIN
  • Also Cited By: 3CAJ

  • PubMed Abstract: 
  • The 3-dimensional structure of human carbonic anhydrase II (HCAII; EC 4.2.1.1) complexed with 3 structurally related inhibitors, 1a, 1b, and 1c, has been determined by X-ray crystallographic methods. The 3 inhibitors (1a = C8H12N2O4S3) vary only in t ...

    The 3-dimensional structure of human carbonic anhydrase II (HCAII; EC 4.2.1.1) complexed with 3 structurally related inhibitors, 1a, 1b, and 1c, has been determined by X-ray crystallographic methods. The 3 inhibitors (1a = C8H12N2O4S3) vary only in the length of the substituent on the 4-amino group: 1a, proton; 1b, methyl; and 1c, ethyl. The binding constants (Ki's) for 1a, 1b, and 1c to HCAII are 1.52, 1.88, and 0.37 nM, respectively. These structures were solved to learn if any structural cause could be found for the difference in binding. In the complex with inhibitors 1a and 1b, electron density can be observed for His-64 and a bound water molecule in the native positions. When inhibitor 1c is bound, the side chain attached to the 4-amino group is positioned so that His-64 can only occupy the alternate position and the bound water is absent. While a variety of factors contribute to the observed binding constants, the major reason 1c binds tighter to HCAII than does 1a or 1b appears to be entropy: the increase in entropy when the bound water molecule is released contributes to the increase in binding and overcomes the small penalty for putting the His-64 side chain in a higher energy state.


    Organizational Affiliation

    Merck Research Laboratories, West Point, Pennsylvania 19486.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CARBONIC ANHYDRASE II
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 3 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
PTS
Query on PTS

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Download CCD File 
A
(4S-TRANS)-4-(AMINO)-5,6-DIHYDRO-6-METHYL-4H-THIENO (2,3-B)THIOPYRAN-2-SULFONAMIDE-7,7-DIOXIDE
C8 H12 N2 O4 S3
HVURBRAECUMAHY-NJGYIYPDSA-N
 Ligand Interaction
MMC
Query on MMC

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Download CCD File 
A
METHYL MERCURY ION
C H3 Hg
DBUXSCUEGJMZAE-UHFFFAOYSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
PTSKi: 1.5 nM (100) BINDINGDB
PTSKi: 1.52 nM BINDINGMOAD
PTSKi: 1.52 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 42.720α = 90.00
b = 41.930β = 104.77
c = 72.690γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
X-PLORmodel building
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1994-01-31
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance