3NRZ

Crystal Structure of Bovine Xanthine Oxidase in Complex with Hypoxanthine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 

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This is version 1.2 of the entry. See complete history


Literature

Substrate orientation and catalytic specificity in the action of xanthine oxidase: the sequential hydroxylation of hypoxanthine to uric acid.

Cao, H.Pauff, J.M.Hille, R.

(2010) J Biol Chem 285: 28044-28053

  • DOI: https://doi.org/10.1074/jbc.M110.128561
  • Primary Citation of Related Structures:  
    3NRZ, 3NS1

  • PubMed Abstract: 

    Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp(2)-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 A resolution and the chemotherapeutic agent 6-mercaptopurine at 2.6 A resolution have been determined, showing in each case two alternate orientations of substrate in the two active sites of the crystallographic asymmetric unit. One orientation is such that it is expected to yield hydroxylation at C-2 of substrate, yielding xanthine. The other suggests hydroxylation at C-8 to give 6,8-dihydroxypurine, a putative product not previously thought to be generated by the enzyme. Kinetic experiments demonstrate that >98% of hypoxanthine is hydroxylated at C-2 rather than C-8, indicating that the second crystallographically observed orientation is significantly less catalytically effective than the former. Theoretical calculations suggest that enzyme selectivity for the C-2 over C-8 of hypoxanthine is largely due to differences in the intrinsic reactivity of the two sites. For the orientation of hypoxanthine with C-2 proximal to the molybdenum center, the disposition of substrate in the active site is such that Arg(880) and Glu(802), previous shown to be catalytically important for the conversion of xanthine to uric acid, play similar roles in hydroxylation at C-2 as at C-8. Contrary to the literature, we find that 6,8-dihydroxypurine is effectively converted to uric acid by xanthine oxidase.


  • Organizational Affiliation

    Department of Biochemistry, University of California at Riverside, Riverside, California 92521, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Xanthine dehydrogenase/oxidaseA,
D [auth J]
164Bos taurusMutation(s): 0 
EC: 1.17.1.4 (PDB Primary Data), 1.17.3.2 (PDB Primary Data)
UniProt
Find proteins for P80457 (Bos taurus)
Explore P80457 
Go to UniProtKB:  P80457
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP80457
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
Xanthine dehydrogenase/oxidaseB,
E [auth K]
305Bos taurusMutation(s): 0 
EC: 1.17.1.4 (PDB Primary Data), 1.17.3.2 (PDB Primary Data)
UniProt
Find proteins for P80457 (Bos taurus)
Explore P80457 
Go to UniProtKB:  P80457
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP80457
Sequence Annotations
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  • Reference Sequence
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
Xanthine dehydrogenase/oxidaseC,
F [auth L]
756Bos taurusMutation(s): 0 
EC: 1.17.1.4 (PDB Primary Data), 1.17.3.2 (PDB Primary Data)
UniProt
Find proteins for P80457 (Bos taurus)
Explore P80457 
Go to UniProtKB:  P80457
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP80457
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 5 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download Ideal Coordinates CCD File 
I [auth B],
O [auth K]
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
MTE
Query on MTE

Download Ideal Coordinates CCD File 
J [auth C],
P [auth L]
PHOSPHONIC ACIDMONO-(2-AMINO-5,6-DIMERCAPTO-4-OXO-3,7,8A,9,10,10A-HEXAHYDRO-4H-8-OXA-1,3,9,10-TETRAAZA-ANTHRACEN-7-YLMETHYL)ESTER
C10 H14 N5 O6 P S2
HPEUEJRPDGMIMY-IFQPEPLCSA-N
FES
Query on FES

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G [auth A],
H [auth A],
M [auth J],
N [auth J]
FE2/S2 (INORGANIC) CLUSTER
Fe2 S2
NIXDOXVAJZFRNF-UHFFFAOYSA-N
MOS
Query on MOS

Download Ideal Coordinates CCD File 
K [auth C],
Q [auth L]
DIOXOTHIOMOLYBDENUM(VI) ION
H Mo O2 S
BDSRWPHSAKXXRG-UHFFFAOYSA-M
HPA
Query on HPA

Download Ideal Coordinates CCD File 
L [auth C],
R [auth L]
HYPOXANTHINE
C5 H4 N4 O
FDGQSTZJBFJUBT-UHFFFAOYSA-N
Binding Affinity Annotations 
IDSourceBinding Affinity
HPA PDBBind:  3NRZ Kd: 4600 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 133.016α = 90
b = 73.645β = 97.05
c = 138.696γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
PDB_EXTRACTdata extraction
MOSFLMdata reduction
SCALAdata scaling
MOLREPphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-07-14
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-12-27
    Changes: Data collection, Database references, Derived calculations