1B6Z

6-PYRUVOYL TETRAHYDROPTERIN SYNTHASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.216 

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This is version 1.2 of the entry. See complete history


Literature

Crystallographic and kinetic investigations on the mechanism of 6-pyruvoyl tetrahydropterin synthase.

Ploom, T.Thony, B.Yim, J.Lee, S.Nar, H.Leimbacher, W.Richardson, J.Huber, R.Auerbach, G.

(1999) J Mol Biol 286: 851-860

  • DOI: 10.1006/jmbi.1998.2511
  • Primary Citation of Related Structures:  
    1B66, 1B6Z

  • PubMed Abstract: 
  • The enzyme 6-pyruvoyl tetrahydropterin synthase (PTPS) catalyses the second step in the de novo biosynthesis of tetrahydrobiopterin, the conversion of dihydroneopterin triphosphate to 6-pyruvoyl tetrahydropterin. The Zn and Mg-dependent reaction includes a triphosphate elimination, a stereospecific reduction of the N5-C6 double bond and the oxidation of both side-chain hydroxyl groups ...

    The enzyme 6-pyruvoyl tetrahydropterin synthase (PTPS) catalyses the second step in the de novo biosynthesis of tetrahydrobiopterin, the conversion of dihydroneopterin triphosphate to 6-pyruvoyl tetrahydropterin. The Zn and Mg-dependent reaction includes a triphosphate elimination, a stereospecific reduction of the N5-C6 double bond and the oxidation of both side-chain hydroxyl groups. The crystal structure of the inactive mutant Cys42Ala of PTPS in complex with its natural substrate dihydroneopterinetriphosphate was determined at 1.9 A resolution. Additionally, the uncomplexed enzyme was refined to 2.0 A resolution. The active site of PTPS consists of the pterin-anchoring Glu A107 neighboured by two catalytic motifs: a Zn(II) binding site and an intersubunit catalytic triad formed by Cys A42, Asp B88 and His B89. In the free enzyme the Zn(II) is in tetravalent co-ordination with three histidine ligands and a water molecule. In the complex the water is replaced by the two substrate side-chain hydroxyl groups yielding a penta-co-ordinated Zn(II) ion. The Zn(II) ion plays a crucial role in catalysis. It activates the protons of the substrate, stabilizes the intermediates and disfavours the breaking of the C1'C2' bond in the pyruvoyl side-chain. Cys A42 is activated by His B89 and Asp B88 for proton abstraction from the two different substrate side-chain atoms C1', and C2'. Replacing Ala A42 in the mutant structure by the wild-type Cys by modelling shows that the C1' and C2' substrate side-chain protons are at equal distances to Cys A42 Sgamma. The basicity of Cys A42 may be increased by a catalytic triad His B89 and Asp B88. The active site of PTPS seems to be optimised to carry out proton abstractions from two different side-chain C1' and C2' atoms, with no obvious preference for one of them. Kinetic studies with dihydroneopterin monophosphate reveal that the triphosphate moiety of the substrate is necessary for enzyme specifity.


    Organizational Affiliation

    Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Am Klopferspitz 18a, Martinsried, 82152, Germany. ploom@biochem.mpg.de



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
6-pyruvoyl tetrahydropterin synthaseA, B140Rattus norvegicusMutation(s): 0 
Gene Names: Pts
EC: 4.6.1.10 (PDB Primary Data), 4.2.3.12 (UniProt)
UniProt
Find proteins for P27213 (Rattus norvegicus)
Explore P27213 
Go to UniProtKB:  P27213
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download Ideal Coordinates CCD File 
C [auth A], D [auth B]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.256 
  • R-Value Work: 0.216 
  • Space Group: P 3 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 121.5α = 90
b = 121.5β = 90
c = 61.25γ = 120
Software Package:
Software NamePurpose
X-PLORrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-01-21
    Type: Initial release
  • Version 1.1: 2008-04-26
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance