Biological Assembly 1  

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

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 66.71 kDa 
• Atom Count: 4,777 
• Modelled Residue Count: 581 
• Deposited Residue Count: 583 
• Unique protein chains: 1

 5IJE

Crystal structure of Equine Serum Albumin in the presence of 30 mM zinc at pH 7.4

• PDB DOI: 10.2210/pdb5IJE/pdb

• Classification: TRANSPORT PROTEIN
• Organism(s): Equus caballus
• Mutation(s): No 


• Deposited: 2016-03-01 Released: 2016-04-27 
• Deposition Author(s): Handing, K.B., Shabalin, I.G., Cooper, D.R., Szlachta, K., Almo, S.C., Minor, W., New York Structural Genomics Research Consortium (NYSGRC)
• Funding Organization(s): National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.40 Å
• R-Value Free: 0.255 
• R-Value Work: 0.195 
• R-Value Observed: 0.199 

Literature

Circulatory zinc transport is controlled by distinct interdomain sites on mammalian albumins.

Handing, K.B., Shabalin, I.G., Kassaar, O., Khazaipoul, S., Blindauer, C.A., Stewart, A.J., Chruszcz, M., Minor, W.

(2016) Chem Sci 7: 6635-6648

• PubMed: 28567254 
• DOI: 10.1039/c6sc02267g
• Primary Citation of Related Structures:  
  5IIH, 5IIU, 5IIX, 5IJ5, 5IJE, 5IJF


• PubMed Abstract: 
  

Zinc is an essential nutrient in the body; it is required for the catalytic activity of many hundreds of human enzymes and virtually all biological processes, therefore its homeostasis and trafficking is of crucial interest. Serum albumin is the major carrier of Zn ²⁺ in the blood and is required for its systemic distribution. Here we present the first crystal structures of human serum albumin (HSA) and equine serum albumin (ESA) in complex with Zn ²⁺ . The structures allow unambiguous identification of the major zinc binding site on these two albumins, as well as several further, weaker zinc binding sites. The major site in both HSA and ESA has tetrahedral geometry and comprises three protein ligands from the sidechains of His67, His247 and Asp249 and a water molecule. Isothermal titration calorimetric studies of a HSA H67A mutant confirm this to be the highest affinity Zn ²⁺ site. Furthermore, analysis of Zn ²⁺ binding to HSA and ESA proved the presence of secondary sites with 20-50-fold weaker affinities, which may become of importance under particular physiological conditions. Both calorimetry and crystallography suggest that ESA possesses an additional site compared to HSA, involving Glu153, His157 and His288. The His157 residue is replaced by Phe in HSA, incapable of metal coordination. Collectively, these findings are critical to our understanding of the role serum albumin plays in circulatory Zn ²⁺ handling and cellular delivery.

---

Organizational Affiliation: 

New York Structural Genomics Research Consortium (NYSGRC) , USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Serum albumin	A	583	Equus caballus	Mutation(s): 0  Gene Names: ALB
UniProt
Find proteins for P35747 (Equus caballus) Explore P35747  Go to UniProtKB:  P35747

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SO4	O [auth A]	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L
ZN	B [auth A], C [auth A], D [auth A], E [auth A], F [auth A], G [auth A], H [auth A], I [auth A], J [auth A], K [auth A], L [auth A], M [auth A], N [auth A]	ZINC ION Zn PTFCDOFLOPIGGS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.40 Å
• R-Value Free: 0.255 
• R-Value Work: 0.195 
• R-Value Observed: 0.199 
• Space Group: P 6₁
• Diffraction Data DOI: 10.18430/M35IJE Protein Diffraction

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 94.384	α = 90
b = 94.384	β = 90
c = 141.905	γ = 120

Software Package:

Software Name	Purpose
REFMAC	refinement
SBC-Collect	data collection
HKL-3000	data collection
SCALEPACK	data scaling
HKL-3000	data reduction
MOLREP	phasing
PDB_EXTRACT	data extraction

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2016-04-27 
Deposition Author(s): Handing, K.B., Shabalin, I.G., Cooper, D.R., Szlachta, K., Almo, S.C., Minor, W., New York Structural Genomics Research Consortium (NYSGRC)

---

Funding Organization	Location	Grant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)	United States	1R01GM117325-01
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)	United States	5U54GM094662-05
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)	United States	R01GM053163

Revision History  

• Version 1.0: 2016-04-27
  Type: Initial release
  
• Version 1.1: 2017-09-20
  Changes: Author supporting evidence, Derived calculations
• Version 1.2: 2017-12-13
  Changes: Database references
• Version 1.3: 2022-03-23
  Changes: Author supporting evidence, Database references, Derived calculations
• Version 1.4: 2022-04-13
  Changes: Database references, Structure summary