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discounted EARLY registration ends Dec 31, 2014
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
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MetaCyc Enzyme: ribonucleoside hydrolase

Gene: NSH1 Accession Number: AT2G36310 (MetaCyc)

Synonyms: At2G36310, URH1

Species: Arabidopsis thaliana col

Summary:
Uridine ribohydrolase, a critical enzyme for uridine degradation, has only been recently cloned from Arabidopsis An in vitro assay with the recombinant protein revealed that uridine is the preferred substrate [Jung09]. Xanthosine was also somewhat favored with a maximal catalytic activity only about 6-fold lower than for uridine [Jung10]. Inosine was hydrolyzed at a much lower rate, and adenosine was even less effective as a substrate. NSH1 can also act on methyluridine [Jung10]. Cytidine was not metabolized as a substrate [Jung09].

Arabidopsis NSH1 over-expression mutants have an increased capability to degrade imported uridine. miRNA- repressed mutants had decreased ability to degrade uridine [Jung09].

Locations: cytosol

Unification Links: PhylomeDB:Q9SJM7 , Pride:Q9SJM7 , Protein Model Portal:Q9SJM7 , SMR:Q9SJM7 , TAIR:At2G36310 , UniProt:Q9SJM7

Relationship Links: InterPro:IN-FAMILY:IPR001910 , InterPro:IN-FAMILY:IPR023186 , Panther:IN-FAMILY:PTHR12304 , Pfam:IN-FAMILY:PF01156 , Prosite:IN-FAMILY:PS01247

Gene-Reaction Schematic: ?

GO Terms:

Cellular Component: GO:0005829 - cytosol [Jung09]

Credits:
Created 23-Jul-2010 by Zhang P , TAIR


Enzymatic reaction of: xanthosine nucleosidase (ribonucleoside hydrolase)

xanthosine + H2O <=> D-ribofuranose + xanthine

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of purines degradation in plants , purine nucleotides degradation I (plants) , superpathway of guanosine nucleotides degradation (plants) , adenosine nucleotides degradation I , guanosine nucleotides degradation I

Summary:
The maximal catalytic activity for xanthosine is 3.02 mmol mg-1 protein hr -1 [Jung10].

Kinetic Parameters:

Substrate
Km (μM)
Citations
xanthosine
1690.0
[Jung10]


Enzymatic reaction of: inosine nucleosidase (ribonucleoside hydrolase)

EC Number: 3.2.2.2

inosine + H2O <=> D-ribofuranose + hypoxanthine

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of purines degradation in plants , purine nucleotides degradation I (plants) , adenosine nucleotides degradation I

Kinetic Parameters:

Substrate
Km (μM)
Citations
inosine
1400.0
[Jung09]


Enzymatic reaction of: adenosine nucleosidase (ribonucleoside hydrolase)

EC Number: 3.2.2.7

adenosine + H2O <=> D-ribofuranose + adenine

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: adenine and adenosine salvage II

Kinetic Parameters:

Substrate
Km (μM)
Citations
adenosine
700.0
[Jung09]


Enzymatic reaction of: uridine ribohydrolase (ribonucleoside hydrolase)

Synonyms: uridine nucleosidase, uridine nucleoside hydrolase

EC Number: 3.2.2.3

uridine + H2O <=> D-ribofuranose + uracil

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of pyrimidine ribonucleosides salvage , pyrimidine ribonucleosides salvage II

Kinetic Parameters:

Substrate
Km (μM)
Citations
uridine
800.0
[Jung09]


References

Jung09: Jung B, Florchinger M, Kunz HH, Traub M, Wartenberg R, Jeblick W, Neuhaus HE, Mohlmann T (2009). "Uridine-ribohydrolase is a key regulator in the uridine degradation pathway of Arabidopsis." Plant Cell 21(3);876-91. PMID: 19293370

Jung10: Jung B, Hoffmann C, Mohlmann T (2010). "Arabidopsis nucleoside hydrolases involved in intracellular and extracellular degradation of purines." Plant J. PMID: 21235647


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 18.5 on Mon Dec 22, 2014, BIOCYC14B.