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Overview for MACiE Entry M0039

Version history

General Information

EC Number: 3.2.2.1 (A member of the Hydrolases, Glycosylases, Hydrolysing N-glycosyl compounds)

Enzyme Name: purine nucleosidase

Biological Species: Crithidia fasciculata (Protozoa)

Catalytic Chain UniprotKB Accession Codes:

  • Q27546 - Inosine-uridine preferring nucleoside hydrolase

Representative PDB Code: 2mas - PURINE NUCLEOSIDE HYDROLASE WITH A TRANSITION STATEINHIBITOR (Resolution = 2.30 Å).

Catalytic CATH Codes:

  • 3.90.245.10 - Inosine-uridine Nucleoside N-ribohydrolase, chain A

"Other" CATH Codes:

  • 3.90.245.10 - Inosine-uridine Nucleoside N-ribohydrolase, chain A

Display structure information

Overall Reaction:

Image of ribosylpurine

Image of water

right arrow

Image of purine

Image of D-ribose

ribosylpurine
C15586
CHEBI:18255
water
C00001
CHEBI:15377
purine
C15587
CHEBI:17258
D-ribose
C00121
CHEBI:16988

Overall Comment: Asp10 Asp14 Asp15 and Asp242 are all at the base of the active site. The first third and fourth all point towards the centre of the cavity and are involved in chelating an electron dense ion.


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Stepwise Description of the Reaction

Step 1Asp14 deprotonates water, which initiates a nucleophilic attack on the C1 of the ribose ring in a substitution reaction which eliminates the purine with concomitant deprotonation of His241.
Step 2His241 deprotonates water and water deprotonates Asp14 in an inferred return step.

View similar reactions (composite manual annotation)


Catalytic Residues Involved

Type Number Chain Location of Function
Asp 10 A Side Chain
Asn 168 A Side Chain
His 241 A Side Chain

Metal Cofactors for M0039

Type Het group Number Chain
calcium CA 133 A Overview

References

  1. M. Degano et al. (1998), Biochemistry, 37, 6277-6285. Trypanosomal nucleoside hydrolase. A novel mechanism from the structure with a transition-state inhibitor.
    Medline: 9572842
  2. D. N. Gopaul et al. (1996), Biochemistry, 35, 5963-5970. Inosine-uridine nucleoside hydrolase from Crithidia fasciculata. Genetic characterization, crystallization, and identification of histidine 241 as a catalytic site residue.
    Medline: 8634237
  3. M. Degano et al. (1996), Biochemistry, 35, 5971-5981. Three-dimensional structure of the inosine-uridine nucleoside N-ribohydrolase from Crithidia fasciculata.
    Medline: 8634238

Homologue information for M0039 (2mas)

CSA Homologues

MACiE Homologues (within the PDB)

MACiE Homologues (within UniprotKB/SwissProt)


Links to this entry in other databases

Link to EC-PDB-SUM Link to PDB-SUM Link to RCSB PDB Link to PDBe Link to CSA
Link to MetaCyc Link to KEGG Link to BRENDA Link to ExplorENZ
Link to EzCatDB

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