1B5M

RAT OUTER MITOCHONDRIAL MEMBRANE CYTOCHROME B5


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Work: 0.220 

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This is version 1.2 of the entry. See complete history


Literature

13C NMR spectroscopic and X-ray crystallographic study of the role played by mitochondrial cytochrome b5 heme propionates in the electrostatic binding to cytochrome c.

Rodriguez-Maranon, M.J.Qiu, F.Stark, R.E.White, S.P.Zhang, X.Foundling, S.I.Rodriguez, V.Schilling 3rd., C.L.Bunce, R.A.Rivera, M.

(1996) Biochemistry 35: 16378-16390

  • DOI: 10.1021/bi961895o
  • Primary Citation of Related Structures:  
    1B5M

  • PubMed Abstract: 
  • The role played by the outer mitochondrial membrane (OM) cytochrome b5 heme propionate groups in the electrostatic binding between OM cytochrome b5 and horse heart cytochrome c was investigated by 13C NMR spectroscopy and X-ray crystallography. To achieve these aims, 13C-labeled heme OM cytochrome b5 was expressed in Escherichia coli as previously described [Rivera M ...

    The role played by the outer mitochondrial membrane (OM) cytochrome b5 heme propionate groups in the electrostatic binding between OM cytochrome b5 and horse heart cytochrome c was investigated by 13C NMR spectroscopy and X-ray crystallography. To achieve these aims, 13C-labeled heme OM cytochrome b5 was expressed in Escherichia coli as previously described [Rivera M., Walker, F.A. (1995) Anal. Biochem. 230, 295-302]. Assignment of the resonances arising from the heme propionate carbons in ferricytochrome b5 was carried out by a combination of one- and two-dimensional NMR experiments. Titrations of [13C]heme-labeled OM cytochrome b5 with horse heart cytochrome c were carried out in order to monitor the resonances arising from the heme propionate carbonyl carbons in OM cytochrome b5. The results from these titrations clearly show that only the heme propionate located on the exposed heme edge in OM cytochrome b5 participates in the electrostatic stabilization of the complex between OM cytochrome b5 and horse heart cytochrome c. Similar experiments carried out monitoring 13C resonances arising from several other heme substituents demonstrated that the stoichiometry of the complex is 1:1. A conditional binding constant, K which equals 3.8 x 10(4) +/- 1.4 x 10(4) at mu = 0.02 M, was obtained for the formation of the complex by fitting the binding curves obtained experimentally to a model based on this stoichiometry. The X-ray crystal structure of rat liver OM cytochrome b5 solved to 2.7 A resolution shows that the structures of bovine liver microsomal cytochrome b5 and rat liver OM cytochrome b5 are almost identical when compared at medium resolution. The similarity between the two structures, combined with the findings that only the heme propionate located on the exposed heme edge of OM cytochrome b5 participates in the electrostatic binding to cytochrome c and that the stability of this complex is similar to that measured for the association between microsomal cytochrome b5 and cytochrome c, clearly indicates that the site of interaction on OM cytochrome b5 is almost identical to the one elucidated for microsomal cytochrome b5. It is therefore possible to conclude that the large body of information gathered by many investigators for the nonphysiological interaction between microsomal cytochrome b5 and cytochrome c (recently reviewed) [Mauk, A. G. Mauk, M. R., Moore, G. R., & Northrup, S. H. (1995) Bioenerg. Biomembr. 27, 311-330] has indeed biological as well as pedagogical validity.


    Organizational Affiliation

    Department of Chemistry, Oklahoma State University, Stillwater 74078, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
CYTOCHROME B5A84Rattus norvegicusMutation(s): 0 
Gene Names: Cyb5bCyb5mOmb5
UniProt
Find proteins for P04166 (Rattus norvegicus)
Explore P04166 
Go to UniProtKB:  P04166
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
B [auth A]PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Work: 0.220 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 30α = 90
b = 30β = 90
c = 219γ = 90
Software Package:
Software NamePurpose
MRCHKmodel building
TNTrefinement
FRAMBOdata reduction
SADIEdata reduction
SAINTdata scaling
MRCHKphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1997-03-12
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance