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MetaCyc Reaction: 2.4.2.1

Superclasses: Reactions Classified By Conversion Type Simple Reactions Chemical Reactions
Reactions Classified By Substrate Small-Molecule Reactions

EC Number: 2.4.2.1

Enzymes and Genes:

Escherichia coli K-12 substr. MG1655 : xanthosine phosphorylase Inferred from experiment : xapA
Glycine max : purine nucleoside phosphorylase
Homo sapiens : purine nucleoside phosphorylase Inferred from experiment : PNP

In Pathway: xanthine and xanthosine salvage , urate biosynthesis/inosine 5'-phosphate degradation , purine ribonucleosides degradation

Note that this reaction equation differs from the official Enzyme Commission reaction equations for this EC number, which can be found here and here .

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

Mass balance status: Balanced.

Enzyme Commission Primary Name: purine-nucleoside phosphorylase

Enzyme Commission Synonyms: inosine phosphorylase, PNPase, PUNPI, PUNPII, inosine-guanosine phosphorylase, nucleotide phosphatase, purine deoxynucleoside phosphorylase, purine deoxyribonucleoside phosphorylase, purine nucleoside phosphorylase, purine ribonucleoside phosphorylase

Standard Gibbs Free Energy (ΔrG in kcal/mol): 0.72998047 Inferred by computational analysis [Latendresse13]

Enzyme Commission Summary:
Specificity not completely determined. Can also catalyse ribosyltransferase reactions of the type catalysed by EC 2.4.2.5, nucleoside ribosyltransferase.

Citations: [Bzowska00, Stoychev02, Agarwal69, Heppel52, Saunders69, Tsuboi57, Friedkin61, Kalckar47]

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Instance reactions of [a purine ribonucleoside + phosphate ↔ a purine base + α-D-ribose-1-phosphate] (2.4.2.1):
i1: inosine + phosphate ↔ hypoxanthine + α-D-ribose-1-phosphate (2.4.2.1)

i2: guanosine + phosphate ↔ guanine + α-D-ribose-1-phosphate (2.4.2.1/2.4.2.15)

i3: adenosine + phosphate ↔ adenine + α-D-ribose-1-phosphate (2.4.2.1)

Unification Links: KEGG:R02297 , Rhea:27638

Relationship Links: BRENDA:EC:2.4.2.1 , ENZYME:EC:2.4.2.1 , IUBMB-ExplorEnz:EC:2.4.2.1


References

Agarwal69: Agarwal RP, Parks RE (1969). "Purine nucleoside phosphorylase from human erythrocytes. IV. Crystallization and some properties." J Biol Chem 244(4);644-7. PMID: 5768862

Bzowska00: Bzowska A, Kulikowska E, Shugar D (2000). "Purine nucleoside phosphorylases: properties, functions, and clinical aspects." Pharmacol Ther 88(3);349-425. PMID: 11337031

Friedkin61: Friedkin M, Kalckar H (1961). "Nucleoside phosphorylases." In: Boyer, P.D., Lardy, H. and Myrbäck, K. (Eds), The Enzymes, 2nd edn, vol. 5, Academic Press, New York, pp. 237-255.

Heppel52: Heppel LA, Hilmoe RJ (1952). "[Phosphorolysis and hydrolysis of purine ribosides by enzymes from yeast]." J Biol Chem 198(2);683-94. PMID: 12999785

Kalckar47: Kalckar HM (1947). "The enzymatic synthesis of purine ribosides." J. Biol. Chem. 167 477-486.

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Saunders69: Saunders PP, Wilson BA, Saunders GF (1969). "Purification and comparative properties of a pyrimidine nucleoside phosphorylase from Bacillus stearothermophilus." J Biol Chem 244(13);3691-7. PMID: 4978445

Stoychev02: Stoychev G, Kierdaszuk B, Shugar D (2002). "Xanthosine and xanthine. Substrate properties with purine nucleoside phosphorylases, and relevance to other enzyme systems." Eur J Biochem 269(16);4048-57. PMID: 12180982

Tsuboi57: Tsuboi KK, Hudson PB (1957). "Enzymes of the human erythrocyte. I. Purine nucleoside phosphorylase; isolation procedure." J Biol Chem 224(2);879-87. PMID: 13405917


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Tue Apr 21, 2015, biocyc14.