Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 75.67 kDa 
• Atom Count: 5072 
• Residue Count: 650 
• Unique protein chains: 1

5H52

Structure of Titanium-bound human serum transferrin

• DOI: 10.2210/pdb5H52/pdb

• Classification: METAL BINDING PROTEIN
• Organism(s): Homo sapiens
• Mutation(s): No 


• Deposited: 2016-11-04 Released: 2017-11-08 
• Deposition Author(s): Curtin, J.P., Wang, M., Sun, H.
• Funding Organization(s): The University of Hong Kong

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.00 Å
• R-Value Free: 0.224 
• R-Value Work: 0.170 
• R-Value Observed: 0.172 

Literature

The role of citrate, lactate and transferrin in determining titanium release from surgical devices into human serum.

Curtin, J.P., Wang, M., Cheng, T., Jin, L., Sun, H.

(2018) J Biol Inorg Chem 23: 471-480

• PubMed: 29623422 
• DOI: 10.1007/s00775-018-1557-5
• Primary Citation of Related Structures:  
  5H52


• PubMed Abstract: 
  

The presence of ionic titanium in the serum of patients with titanium implants is currently unexplained. This is presumed due to corrosion, and yet the serum titanium concentration measured in patients is far greater than that predicted by its solubility. The binding of titanium ion as Ti(IV) to human transferrin (hTF) in serum indicates that Ti(IV) ions interact with human physiology. This is an intriguing finding since there is currently no known role for titanium ions in human physiology. Thus, understanding the factors that determine in vivo titanium ion release is relevant to further understanding this metal's interactions with human biochemistry. The present study sought to determine the extent of titanium ion release of into human serum in vitro, and the role of citrate, lactate and hTF in this process. It was found that, when surgical devices of commercially pure titanium were placed into human serum, citrate and lactate concentrations were the prime determinants of titanium release. Crystallography revealed Ti(IV) bound to hTF in the presence of citrate alone, signalling that citrate can act as an independent ligand for Ti(IV) binding to hTF. Based on these findings, a two-stage process of titanium ion release into human serum that is dependent upon both citrate and hTF is proposed to explain the ongoing presence of titanium ion in human subjects with implanted titanium devices.

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Organizational Affiliation: 

Department of Chemistry, The University of Hong Kong, Hong Kong, China.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Serotransferrin	A	679	Homo sapiens	Mutation(s): 0  Gene Names: TF, PRO1400
Find proteins for P02787 (Homo sapiens) Explore P02787  Go to UniProtKB:  P02787
NIH Common Fund Data Resources
PHAROS:  P02787 GTEx:  ENSG00000091513

Small Molecules

Ligands 3 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CIT	A	CITRIC ACID C6 H8 O7 KRKNYBCHXYNGOX-UHFFFAOYSA-N
MLI	A	MALONATE ION C3 H2 O4 OFOBLEOULBTSOW-UHFFFAOYSA-L
4TI	A	TITANIUM ION Ti VEOOXLFYKHRLHJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.00 Å
• R-Value Free: 0.224 
• R-Value Work: 0.170 
• R-Value Observed: 0.172 
• Space Group: C 2 2 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 138.977	α = 90
b = 156.667	β = 90
c = 107.855	γ = 90

Software Package:

Software Name	Purpose
SCALEPACK	data scaling
PHASER	phasing
REFMAC	refinement
PDB_EXTRACT	data extraction
PHASER	phasing
HKL-2000	data reduction

Structure Validation

Entry History & Funding Information

Deposition Data

• Deposited Date: 2016-11-04 
• Released Date: 2017-11-08 
Deposition Author(s): Curtin, J.P., Wang, M., Sun, H.

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Funding Organization	Location	Grant Number
The University of Hong Kong	Hong Kong	8100013

Revision History 

• Version 1.0: 2017-11-08
  Type: Initial release
  
• Version 1.1: 2018-04-25
  Changes: Data collection, Database references
• Version 1.2: 2018-05-23
  Changes: Data collection, Database references