Binding of Phosphate and Pyrophosphate ions at the active site of human angiogenin as revealed by X-ray Crystallography

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 

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Binding of Phosphate and Pyrophosphate Ions at the Active Site of Human Angiogenin as Revealed by X-Ray Crystallography

Leonidas, D.D.Chavali, G.B.Jardine, A.M.Li, S.Shapiro, R.Acharya, K.R.

(2001) Protein Sci 10: 1669

  • DOI: https://doi.org/10.1110/ps.13601
  • Primary Citation of Related Structures:  
    1H52, 1H53, 1HBY

  • PubMed Abstract: 

    Human angiogenin (Ang) is an unusual homolog of bovine pancreatic RNase A that utilizes its ribonucleolytic activity to induce the formation of new blood vessels. The pyrimidine-binding site of Ang was shown previously to be blocked by glutamine 117, indicating that Ang must undergo a conformational change to bind and cleave RNA. The mechanism and nature of this change are not known, and no Ang-inhibitor complexes have been characterized structurally thus far. Here, we report crystal structures for the complexes of Ang with the inhibitors phosphate and pyrophosphate, and the structure of the complex of the superactive Ang variant Q117G with phosphate, all at 2.0 A resolution. Phosphate binds to the catalytic site of both Ang and Q117G in essentially the same manner observed in the RNase A-phosphate complex, forming hydrogen bonds with the side chains of His 13, His 114, and Gln 12, and the main chain of Leu 115; it makes an additional interaction with the Lys 40 ammonium group in the Ang complex. One of the phosphate groups of pyrophosphate occupies a similar position. The other phosphate extends toward Gln 117, and lies within hydrogen-bonding distance from the side-chain amide of this residue as well as the imidazole group of His 13 and the main-chain oxygen of Leu 115. The pyrimidine site remains obstructed in all three complex structures, that is, binding to the catalytic center is not sufficient to trigger the conformational change required for catalytic activity, even in the absence of the Gln 117 side chain. The Ang-pyrophosphate complex structure suggests how nucleoside pyrophosphate inhibitors might bind to Ang; this information may be useful for the design of Ang antagonists as potential anti-angiogenic drugs.

  • Organizational Affiliation

    Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ANGIOGENIN123Homo sapiensMutation(s): 1 
UniProt & NIH Common Fund Data Resources
Find proteins for P03950 (Homo sapiens)
Explore P03950 
Go to UniProtKB:  P03950
PHAROS:  P03950
GTEx:  ENSG00000214274 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP03950
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PO4

Download Ideal Coordinates CCD File 
O4 P
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on PCA
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.230 
  • R-Value Work: 0.185 
  • R-Value Observed: 0.185 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86.206α = 90
b = 38.405β = 90
c = 33.568γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-08-09
    Type: Initial release
  • Version 1.1: 2011-05-07
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2020-03-11
    Changes: Derived calculations, Polymer sequence
  • Version 2.1: 2023-12-13
    Changes: Data collection, Database references, Refinement description