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MS
unreviewed

Purine nucleoside phosphorylase (PNP)

4 reactions · 2 pathways

Cofactors used

Clinical / pharmacological. PNP deficiency: T-cell immunodeficiency

What it does, reaction by reaction

4 reactions

Purine Degradation (to Uric Acid) Nucleotide Metabolism · Cytosol

step 5 Irreversible/directional

Inosine → hypoxanthine

Converts Inosine into Hypoxanthine

Notes

PNP catalyzes inosine + Pi ⇌ hypoxanthine + ribose 1-phosphate. In catabolic tissues, the reaction commonly proceeds toward free hypoxanthine.

step 9 Irreversible/directional

Guanosine → guanine

Converts Guanosine into Guanine

Notes

PNP catalyzes guanosine + Pi ⇌ guanine + ribose 1-phosphate.

Purine Salvage Pathway Nucleotide Metabolism · Cytosol

step 5 Reversible

Inosine → hypoxanthine + ribose 1-phosphate

Converts Inosine into Hypoxanthine Ribose-1-phosphate

Notes

Purine nucleoside phosphorylase (PNP) catalyzes inosine + Pi ⇌ hypoxanthine + ribose 1-phosphate. Although this reaction is reversible and is often viewed as degradative, the liberated hypoxanthine can immediately enter the HGPRT reaction in an operational salvage sequence.

step 6 Irreversible/directional

Guanosine → guanine + ribose 1-phosphate

Converts Guanosine into Guanine Ribose-1-phosphate

Notes

PNP catalyzes guanosine + Pi ⇌ guanine + ribose 1-phosphate. Guanine can then be salvaged by HGPRT; direction in vivo depends on substrate and phosphate concentrations.

Showing all 4 reactions.

What accelerates and inhibits it

Regulation is pathway-specific, so each context is listed separately

0 entries

No regulation recorded for this enzyme in the source documents.

Recent literature

Europe PMC · from cache · sorted by publication date

  1. 1
  2. 2
    Triptolide loaded cerium oxide nanozyme based oral nanoplatform for targeted colitis therapy.

    Lu J, Chen Y, Ding W, Zheng S, Yang L, Wang Y, Ji Q, Qi C, Gao F. · 2026-06-18

    unreviewed
  3. 3
    Synergistic application of taurine and spermidine enhances wheat tolerance to neodymium stress through redox homeostasis, metabolic adjustment, and nutrient regulation.

    Iqbal R, Mehmood H, Majeed A, Murtaza G, Rebouh NY, Alotaibi MS, Alotaibi SS, Ullah S, Huseynova A, Ali S. · 2026-06-15

    open access unreviewed
  4. 4
    High-throughput identification of bacterial β-glucuronidase inhibitors using machine learning.

    Zhang B, Yue H, Skalse A, Sangfuang N, Shorthouse D, Gaisford S, Basit AW. · 2026-06-05

    open access unreviewed
  5. 5
    Two-step bioconversion of pyridoxal 5'-phosphate from pyridoxine through cofactor regeneration and pyridoxine 5'-phosphate oxidase evolution.

    Yang X, Lu B, Wang M, Chen Y, Lu X, Tao Y, Huang J, Ke C. · 2026-04-06

    open access unreviewed
  6. 6
    Efficient whole-cell biotransformation for gastrodin production via glycosyltransferase engineering and process optimization.

    Wang X, Zhang J, Li T, Wang F, Wang Z, Li X. · 2026-04-06

    open access unreviewed
  7. 7
  8. 8
    Porcine serum maltase-glucoamylase: structure, kinetics, and inhibition.

    Watanabe K, Tagami T, Biwa C, Kawasaki M, Adachi N, Moriya T, Senda T, Okuyama M. · 2026-01-14

    open access unreviewed
  9. 9
    Bioengineered titanium implants functionalized with aptamer-valproic acid conjugates orchestrate macrophage programming and mesenchymal stem cell homing for improved osseointegration.

    Sun D, Zhou Q, Guo X, Shi H, Wang X, Li X, Zheng Z, Zhong L, Cao S, Shan R, Su Z, Ma C, Zhao L. · 2026-06-06

    open access unreviewed
  10. 10
    Comprehensive analysis of the association between perfluorooctanoic acid exposure and osteosarcoma progression.

    Dong Y, Zheng J, Dong X, Lv Y, Xu Z, Ye C, Zhu S, Dong H, Lv Y. · 2026-07-16

    unreviewed

External claims. These come from an index outside this database and are not checked against it. Treat them as leads.