1M6C

V68N MYOGLOBIN WITH CO


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Stabilizing bound O2 in myoglobin by valine68 (E11) to asparagine substitution.

Krzywda, S.Murshudov, G.N.Brzozowski, A.M.Jaskolski, M.Scott, E.E.Klizas, S.A.Gibson, Q.H.Olson, J.S.Wilkinson, A.J.

(1998) Biochemistry 37: 15896-15907

  • DOI: 10.1021/bi9812470
  • Primary Citation of Related Structures:  
    1MWD, 1MWC, 1M6M, 1M6C, 1MDN, 1MNO

  • PubMed Abstract: 
  • The isopropyl side chain of valine68 in myoglobin has been replaced by the acetamide side chain of asparagine in an attempt to engineer higher oxygen affinity. The asparagine replacement introduces a second hydrogen bond donor group into the distal heme pocket which could further stabilize bound oxygen ...

    The isopropyl side chain of valine68 in myoglobin has been replaced by the acetamide side chain of asparagine in an attempt to engineer higher oxygen affinity. The asparagine replacement introduces a second hydrogen bond donor group into the distal heme pocket which could further stabilize bound oxygen. The Val68 to Asn substitution leads to approximately 3-fold increases in oxygen affinity and 4-6-fold decreases in CO affinity. As a result, the M-value (KCO/KO2) is lowered 15-20-fold to a value close to unity. An even larger enhancement of O2 affinity is seen when asparagine68 is inserted into H64L sperm whale myoglobin which lacks a distal histidine. The overall rate constants for oxygen and carbon monoxide binding to the single V68N myoglobin mutants are uniformly lower than those for the wild-type protein. In contrast, the overall rate constant for NO association is unchanged. Analyses of time courses monitoring the geminate recombination of ligands following nanosecond and picosecond flash photolysis of MbNO and MbO2 indicate that the barrier to ligand binding from within the heme pocket has been raised with little effect on the barrier to diffusion of the ligand into the pocket from the solvent. The crystal structures of the aquomet, deoxy, oxy, and carbon monoxy forms of the V68N mutant have been determined to resolutions ranging from 1.75 to 2.2 A at 150 K. The overall structures are very similar to those of the wild-type protein with the principal alterations taking place within and around the distal heme pocket. In all four structures the asparagine68 side chain lies almost parallel to the plane of the heme with its amide group directed toward the back of the distal heme pocket. The coordinated water molecule in the aquomet form and the bound oxygen in the oxy form can form hydrogen-bonding interactions with both the Asn68 amide group and the imidazole side chain of His64. Surprisingly, in the carbon monoxy form of the V68N mutant, the histidine64 side chain has swung completely out the distal pocket, its place being taken by two ordered water molecules. Overall, these functional and structural results show that the asparagine68 side chain (i) forms a strong hydrogen bond with bound oxygen through its -NH2 group but (ii) sterically hinders the approach of ligands to the iron from within the distal heme pocket.


    Organizational Affiliation

    Department of Chemistry, University of York, UK.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PROTEIN (MYOGLOBIN)A, B153Sus scrofaMutation(s): 1 
Gene Names: MB
UniProt
Find proteins for P02189 (Sus scrofa)
Explore P02189 
Go to UniProtKB:  P02189
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
C [auth A], E [auth B]PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
CMO
Query on CMO

Download Ideal Coordinates CCD File 
D [auth A], F [auth B]CARBON MONOXIDE
C O
UGFAIRIUMAVXCW-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.192 
  • Space Group: I 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 122.14α = 90
b = 42.3β = 92.49
c = 91.55γ = 90
Software Package:
Software NamePurpose
CCP4model building
REFMACrefinement
DENZOdata reduction
CCP4data scaling
CCP4phasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-08-19
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance