Q8U2I1 · PNPH_PYRFU

Function

function

Purine nucleoside phosphorylase which is highly specific for 6-oxopurine nucleosides. Cleaves guanosine or inosine to respective bases and sugar-1-phosphate molecules. Involved in purine salvage.

Miscellaneous

Although this enzyme belongs to the family of MTA phosphorylases based on sequence homology, it has been shown that conserved amino acid substitutions in the substrate binding pocket convert the substrate specificity of this enzyme from 6-aminopurines to 6-oxopurines. It seems that P.furiosus has developed a specific enzyme (PF0853) for the metabolism of 6-oxo-purines, next to the canonical MTA phosphorylase PF0016.

Catalytic activity

Kinetics

KM SUBSTRATE pH TEMPERATURE[C] NOTES EVIDENCE
322 μMinosine
310 μMinosine
122 μMguanosine
1454 μMadenosine
kcat is 84 sec-1 with inosine as substrate (PubMed:17419725).
kcat is 150 sec-1 with inosine as substrate (PubMed:21683167).
kcat is 28 sec-1 with guanosine as substrate (PubMed:17419725).
kcat is 0.15 sec-1 with adenosine as substrate (PubMed:21683167).

Temperature Dependence

Optimum temperature is 120 degrees Celsius. Thermostable up to 133 degrees Celsius.

Pathway

Purine metabolism; purine nucleoside salvage.

Features

Showing features for binding site, site.

TypeIDPosition(s)Description
Binding site10phosphate (UniProtKB | ChEBI)
Binding site49-50phosphate (UniProtKB | ChEBI)
Binding site82-83phosphate (UniProtKB | ChEBI)
Site169Important for substrate specificity
Binding site187substrate
Binding site188phosphate (UniProtKB | ChEBI)
Binding site211-213substrate
Site223Important for substrate specificity

GO annotations

AspectTerm
Molecular Functionguanosine phosphorylase activity
Molecular FunctionS-methyl-5-thioadenosine phosphorylase activity
Biological Processpurine ribonucleoside salvage

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    6-oxopurine nucleoside phosphorylase
  • EC number
  • Alternative names
    • Purine nucleoside phosphorylase
      (PNP
      ; PfPNP
      )

Gene names

    • Ordered locus names
      PF0853

Organism names

Accessions

  • Primary accession
    Q8U2I1

Proteomes

Phenotypes & Variants

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis169Decreases catalytic activity for insosine and allows the enzyme to phosphorolytically cleave MTA with a catalytic efficiency about 4-fold higher than for inosine; when associated with D-211, D-213 and A-223.
Mutagenesis211Decreases catalytic activity for insosine and allows the enzyme to phosphorolytically cleave MTA with a catalytic efficiency about 4-fold higher than for inosine; when associated with S-169, D-213 and A-223.
Mutagenesis213Decreases catalytic activity for insosine and allows the enzyme to phosphorolytically cleave MTA with a catalytic efficiency about 4-fold higher than for inosine; when associated with S-169, D-211 and A-223.
Mutagenesis223Decreases catalytic activity for insosine and allows the enzyme to phosphorolytically cleave MTA with a catalytic efficiency about 4-fold higher than for inosine; when associated with S-169, D-211 and D-213.
Mutagenesis254Fully active, but reduces thermodynamic and kinetic stability of the enzyme; when associated with S-256.
Mutagenesis256Fully active, but reduces thermodynamic and kinetic stability of the enzyme; when associated with S-254.

PTM/Processing

Features

Showing features for initiator methionine, chain, disulfide bond.

TypeIDPosition(s)Description
Initiator methionine1Removed
ChainPRO_00004150862-2656-oxopurine nucleoside phosphorylase
Disulfide bond136↔202
Disulfide bond162↔190
Disulfide bond254↔256

Keywords

Proteomic databases

Interaction

Subunit

Homohexamer. Dimer of a homotrimer.

Protein-protein interaction databases

Structure

Family & Domains

Sequence similarities

Belongs to the PNP/MTAP phosphorylase family. MTAP subfamily.

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    265
  • Mass (Da)
    29,208
  • Last updated
    2002-06-01 v1
  • Checksum
    19BF1EBBB2FEDBB8
MPRIAIVGGSGVYDFPAENKREETVKTPYGEVKITVGVVGDEEVAFLARHGKGHSIPPHKINYRANIWALYELGVERIIATSAVGSMNPEMKPGDFVILDQIIDFTVSRPRTFYDGEESPHERKFVAHVDFTEPYCPEIRKALITAARNLGLPYHPRGTYVCTEGPRFETAAEIRAYRILGGDVVGMTQCPEAILARELEMCYATVAIVTNYAAGMSGKKLTHSEVVELMQKKSEDIVKLILAAIPLIPKERRCGCKDALKGATG

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
AE009950
EMBL· GenBank· DDBJ
AAL80977.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

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