KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | kinetic analysis, kinetic isotope effeccts, quantum mechanical and molecular mechanical (QM/MM) molecular dynamics (MD) simulations, overview | Homo sapiens |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
inosine + phosphate | Homo sapiens | - |
hypoxanthine + alpha-D-ribose 1-phosphate | - |
r |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P00491 | - |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
purine ribonucleoside + phosphate = purine + alpha-D-ribose 1-phosphate | the structure of hPNP is a homotrimer with the catalytic sites near the subunit interfaces. The ternary complex of hPNP includes the binding of inosine and hydrogen phosphate to the active site. The reaction consists of a phosphorolysis at C1' of inosine's ribose with inversion of stereochemistry at this position. Reaction occurs via an SN1-like mechanism where hydrogen phosphate nucleophile and the purine base leaving group are separated from the oxocarbenium ion, defining a dissociative transition state. It has to be pointed out that the reaction involves annihilation of charges in going from the reactant state to the product state. Reaction mechanism analysis, quantum mechanical and molecular mechanical (QM/MM) molecular dynamics (MD) simulations, detailed overview | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
inosine + phosphate | - |
Homo sapiens | hypoxanthine + alpha-D-ribose 1-phosphate | - |
r |
Subunits | Comment | Organism |
---|---|---|
homotrimer | the structure of hPNP is a homotrimer with the catalytic sites near the subunit interfaces. The ternary complex of hPNP includes the binding of inosine and hydrogen phosphate to the active site | Homo sapiens |
Synonyms | Comment | Organism |
---|---|---|
hPNP | - |
Homo sapiens |
PNP | - |
Homo sapiens |
purine nucleoside phosphorylase | - |
Homo sapiens |
General Information | Comment | Organism |
---|---|---|
additional information | effect of heavy isotope labeling on the reaction catalyzed by human purine nucleoside phosphorylase (hPNP) to elucidate the origin of its catalytic effect and of the enzymatic kinetic isotope effect (EKIE). Using quantum mechanical and molecular mechanical (QM/MM) molecular dynamics (MD) simulations, the mechanism of the hPNP enzymeis investigated and the dynamic effects by means of the calculation of the recrossing transmission coefficient. The simulations reveal that the chemical reaction is slightly slower in the heavy enzyme than in its light counterpart enzyme because protein motions coupled to the reaction coordinate are slower. Thus, protein dynamics have a small but measurable effect on the chemical reaction rate | Homo sapiens |