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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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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 [Jung10a]. Inosine was hydrolyzed at a much lower rate, and adenosine was even less effective as a substrate. NSH1 can also act on methyluridine [Jung10a]. 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 [Jung10a].

Kinetic Parameters:

Substrate
Km (μM)
Citations
xanthosine
1690.0
[Jung10a]


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

Jung10a: 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 Thu Nov 27, 2014, BIOCYC14B.