Q8U2I1 · PNPH_PYRFU
- Protein6-oxopurine nucleoside phosphorylase
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids265 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
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
- a purine D-ribonucleoside + phosphate = a purine nucleobase + alpha-D-ribose 1-phosphate
Kinetics
KM | SUBSTRATE | pH | TEMPERATURE[C] | NOTES | EVIDENCE | |
---|---|---|---|---|---|---|
322 μM | inosine | |||||
310 μM | inosine | |||||
122 μM | guanosine | |||||
1454 μM | adenosine |
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).
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.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 10 | phosphate (UniProtKB | ChEBI) | ||||
Sequence: S | ||||||
Binding site | 49-50 | phosphate (UniProtKB | ChEBI) | ||||
Sequence: RH | ||||||
Binding site | 82-83 | phosphate (UniProtKB | ChEBI) | ||||
Sequence: SA | ||||||
Site | 169 | Important for substrate specificity | ||||
Sequence: E | ||||||
Binding site | 187 | substrate | ||||
Sequence: M | ||||||
Binding site | 188 | phosphate (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 211-213 | substrate | ||||
Sequence: NYA | ||||||
Site | 223 | Important for substrate specificity | ||||
Sequence: H |
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | guanosine phosphorylase activity | |
Molecular Function | S-methyl-5-thioadenosine phosphorylase activity | |
Biological Process | purine ribonucleoside salvage |
Keywords
- Molecular function
- Biological process
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended name6-oxopurine nucleoside phosphorylase
- EC number
- Alternative names
Gene names
Organism names
- Strain
- Taxonomic lineageArchaea > Euryarchaeota > Thermococci > Thermococcales > Thermococcaceae > Pyrococcus
Accessions
- Primary accessionQ8U2I1
Proteomes
Phenotypes & Variants
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 169 | Decreases 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. | ||||
Sequence: E → S | ||||||
Mutagenesis | 211 | Decreases 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. | ||||
Sequence: N → D | ||||||
Mutagenesis | 213 | Decreases 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. | ||||
Sequence: A → D | ||||||
Mutagenesis | 223 | Decreases 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. | ||||
Sequence: H → A | ||||||
Mutagenesis | 254 | Fully active, but reduces thermodynamic and kinetic stability of the enzyme; when associated with S-256. | ||||
Sequence: C → S | ||||||
Mutagenesis | 256 | Fully active, but reduces thermodynamic and kinetic stability of the enzyme; when associated with S-254. | ||||
Sequence: C → S |
PTM/Processing
Features
Showing features for initiator methionine, chain, disulfide bond.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Initiator methionine | 1 | Removed | ||||
Sequence: M | ||||||
Chain | PRO_0000415086 | 2-265 | 6-oxopurine nucleoside phosphorylase | |||
Sequence: PRIAIVGGSGVYDFPAENKREETVKTPYGEVKITVGVVGDEEVAFLARHGKGHSIPPHKINYRANIWALYELGVERIIATSAVGSMNPEMKPGDFVILDQIIDFTVSRPRTFYDGEESPHERKFVAHVDFTEPYCPEIRKALITAARNLGLPYHPRGTYVCTEGPRFETAAEIRAYRILGGDVVGMTQCPEAILARELEMCYATVAIVTNYAAGMSGKKLTHSEVVELMQKKSEDIVKLILAAIPLIPKERRCGCKDALKGATG | ||||||
Disulfide bond | 136↔202 | |||||
Sequence: CPEIRKALITAARNLGLPYHPRGTYVCTEGPRFETAAEIRAYRILGGDVVGMTQCPEAILARELEMC | ||||||
Disulfide bond | 162↔190 | |||||
Sequence: CTEGPRFETAAEIRAYRILGGDVVGMTQC | ||||||
Disulfide bond | 254↔256 | |||||
Sequence: CGC |
Keywords
- PTM
Proteomic databases
Interaction
Structure
Sequence
- Sequence statusComplete
- Length265
- Mass (Da)29,208
- Last updated2002-06-01 v1
- Checksum19BF1EBBB2FEDBB8
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
AE009950 EMBL· GenBank· DDBJ | AAL80977.1 EMBL· GenBank· DDBJ | Genomic DNA |