6CTC

Crystal structure of human transferrin bound to Triferic FPC iron pyrophosphate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.184 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Ferric pyrophosphate citrate: interactions with transferrin.

Pratt, R.Handelman, G.J.Edwards, T.E.Gupta, A.

(2018) Biometals 31: 1081-1089

  • DOI: 10.1007/s10534-018-0142-2
  • Primary Citation of Related Structures:  
    6CTC

  • PubMed Abstract: 
  • There are several options available for intravenous application of iron supplements, but they all have a similar structure:-an iron core surrounded by a carbohydrate coating. These nanoparticles require processing by the reticuloendothelial system to rel ...

    There are several options available for intravenous application of iron supplements, but they all have a similar structure:-an iron core surrounded by a carbohydrate coating. These nanoparticles require processing by the reticuloendothelial system to release iron, which is subsequently picked up by the iron-binding protein transferrin and distributed throughout the body, with most of the iron supplied to the bone marrow. This process risks exposing cells and tissues to free iron, which is potentially toxic due to its high redox activity. A new parenteral iron formation, ferric pyrophosphate citrate (FPC), has a novel structure that differs from conventional intravenous iron formulations, consisting of an iron atom complexed to one pyrophosphate and two citrate anions. In this study, we show that FPC can directly transfer iron to apo-transferrin. Kinetic analyses reveal that FPC donates iron to apo-transferrin with fast binding kinetics. In addition, the crystal structure of transferrin bound to FPC shows that FPC can donate iron to both iron-binding sites found within the transferrin structure. Examination of the iron-binding sites demonstrates that the iron atoms in both sites are fully encapsulated, forming bonds with amino acid side chains in the protein as well as pyrophosphate and carbonate anions. Taken together, these data demonstrate that, unlike intravenous iron formulations, FPC can directly and rapidly donate iron to transferrin in a manner that does not expose cells and tissues to the damaging effects of free, redox-active iron.


    Organizational Affiliation

    University of California Irvine, Orange, CA, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Serotransferrin A679Homo sapiensMutation(s): 0 
Gene Names: TFPRO1400
Find proteins for P02787 (Homo sapiens)
Explore P02787 
Go to UniProtKB:  P02787
NIH Common Fund Data Resources
PHAROS:  P02787
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
POP
Query on POP

Download Ideal Coordinates CCD File 
A
PYROPHOSPHATE 2-
H2 O7 P2
XPPKVPWEQAFLFU-UHFFFAOYSA-L
 Ligand Interaction
CO3
Query on CO3

Download Ideal Coordinates CCD File 
A
CARBONATE ION
C O3
BVKZGUZCCUSVTD-UHFFFAOYSA-L
 Ligand Interaction
FE
Query on FE

Download Ideal Coordinates CCD File 
A
FE (III) ION
Fe
VTLYFUHAOXGGBS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.60 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.184 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 74.37α = 90
b = 90.16β = 90
c = 110.43γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2018-10-24
    Type: Initial release
  • Version 1.1: 2018-11-28
    Changes: Data collection, Database references