1M20

Crystal Structure of F35Y Mutant of Trypsin-solubilized Fragment of Cytochrome b5


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.193 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

X-ray crystallography, CD and kinetic studies revealed the essence of the abnormal behaviors of the cytochrome b5 Phe35-->Tyr mutant.

Yao, P.Wu, J.Wang, Y.H.Sun, B.Y.Xia, Z.X.Huang, Z.X.

(2002) Eur.J.Biochem. 269: 4287-4296


  • PubMed Abstract: 
  • Conserved phenylalanine 35 is one of the hydrophobic patch residues on the surface of cytochrome b5 (cyt b5). This patch is partially exposed on the surface of cyt b5 while its buried face is in direct van der Waals' contact with heme b. Residues Phe ...

    Conserved phenylalanine 35 is one of the hydrophobic patch residues on the surface of cytochrome b5 (cyt b5). This patch is partially exposed on the surface of cyt b5 while its buried face is in direct van der Waals' contact with heme b. Residues Phe35 and Phe/Tyr74 also form an aromatic channel with His39, which is one of the axial ligands of heme b. By site-directed mutagenesis we have produced three mutants of cyt b5: Phe35-->Tyr, Phe35-->Leu, and Phe35-->His. We found that of these three mutants, the Phe35-->Tyr mutant displays abnormal properties. The redox potential of the Phe35-->Tyr mutant is 66 mV more negative than that of the wild-type cyt b5 and the oxidized Phe35-->Tyr mutant is more stable towards thermal and chemical denaturation than wild-type cyt b5. In this study we studied the most interesting mutant, Phe35-->Tyr, by X-ray crystallography, thermal denaturation, CD and kinetic studies of heme dissociation to explore the origin of its unusual behaviors. Analysis of crystal structure of the Phe35-->Tyr mutant shows that the overall structure of the mutant is basically the same as that of the wild-type protein. However, the introduction of a hydroxyl group in the heme pocket, and the increased van der Waals' and electrostatic interactions between the side chain of Tyr35 and the heme probably result in enhancement of stability of the Phe35-->Tyr mutant. The kinetic difference of the heme trapped by the heme pocket also supports this conclusion. The detailed conformational changes of the proteins in response to heat have been studied by CD for the first time, revealing the existence of the folding intermediate.


    Organizational Affiliation

    Chemical Biology Laboratory, Department of Chemistry, Fudan University, Shanghai, People's Republic of China.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cytochrome b5
A
82Bos taurusGene Names: CYB5A (CYB5)
Find proteins for P00171 (Bos taurus)
Go to Gene View: CYB5A
Go to UniProtKB:  P00171
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download SDF File 
Download CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.227 
  • R-Value Work: 0.193 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 70.709α = 90.00
b = 40.388β = 111.72
c = 39.299γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SCALEPACKdata scaling
X-PLORmodel building
DENZOdata reduction
X-PLORphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-09-11
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance