2A75

Trypanosoma rangeli Sialidase In Complex With 2,3- Difluorosialic Acid (Covalent Intermediate)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.174 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structural and Kinetic Analysis of Two Covalent Sialosyl-Enzyme Intermediates on Trypanosoma rangeli Sialidase.

Watts, A.G.Oppezzo, P.Withers, S.G.Alzari, P.M.Buschiazzo, A.

(2006) J.Biol.Chem. 281: 4149-4155

  • DOI: 10.1074/jbc.M510677200
  • Primary Citation of Related Structures:  2AGS, 2FHR

  • PubMed Abstract: 
  • Trypanosoma rangeli sialidase is a glycoside hydrolase (family GH33) that catalyzes the cleavage of alpha-2-->3-linked sialic acid residues from sialoglycoconjugates with overall retention of anomeric configuration. Retaining glycosidases usually ope ...

    Trypanosoma rangeli sialidase is a glycoside hydrolase (family GH33) that catalyzes the cleavage of alpha-2-->3-linked sialic acid residues from sialoglycoconjugates with overall retention of anomeric configuration. Retaining glycosidases usually operate through a ping-pong mechanism, wherein a covalent intermediate is formed between the carbohydrate and an active site carboxylic acid of the enzyme. Sialidases, instead, appear to use a tyrosine as the catalytic nucleophile, leaving the possibility of an essentially different catalytic mechanism. Indeed, a direct nucleophilic role for a tyrosine was shown for the homologous trans-sialidase from Trypanosoma cruzi, although itself not a typical sialidase. Here we present the three-dimensional structures of the covalent glycosyl-enzyme complexes formed by the T. rangeli sialidase with two different mechanism-based inactivators at 1.9 and 1.7 Angstroms resolution. To our knowledge, these are the first reported structures of enzymatically competent covalent intermediates for a strictly hydrolytic sialidase. Kinetic analyses have been carried out on the formation and turnover of both intermediates, showing that structural modifications to these inactivators can be used to modify the lifetimes of covalent intermediates. These results provide further evidence that all sialidases likely operate through a similar mechanism involving the transient formation of a covalently sialylated enzyme. Furthermore, we believe that the ability to "tune" the inactivation and reactivation rates of mechanism-based inactivators toward specific enzymes represents an important step toward developing this class of inactivators into therapeutically useful compounds.


    Organizational Affiliation

    Department of Chemistry, University of British Columbia, Vancouver, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
sialidase
A
652Trypanosoma rangeliEC: 3.2.1.18
Find proteins for O44049 (Trypanosoma rangeli)
Go to UniProtKB:  O44049
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
FSI
Query on FSI

Download SDF File 
Download CCD File 
A
5-(acetylamino)-3,5-dideoxy-3-fluoro-D-erythro-alpha-L-manno-non-2-ulopyranosonic acid
3-FLUOROSIALIC ACID
C11 H18 F N O9
ALJLGESFXXDPKH-RISWTRDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.174 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 74.218α = 90.00
b = 96.102β = 90.00
c = 106.648γ = 90.00
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
CCP4data scaling
PDB_EXTRACTdata extraction
CNSrefinement
CNSphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-11-22
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description