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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: UDP-D-glucuronic acid 4-epimerase

Gene: GAE4 Accession Number: AT2G45310 (MetaCyc)

Synonyms: UGlcAE1, UDP-D-GlcA 4-epimerase, UDP-D-glucuronate 4-epimerase, UDP-D-galacturonic acid 4-epimerase, UDP-D-galacturonate 4-epimerase, UDP-D-GalA 4-epimerase

Species: Arabidopsis thaliana col

Subunit composition of UDP-D-glucuronic acid 4-epimerase = [GAE4]2
         subunit of UDP-GlcA 4-epimerase = GAE4

Summary:
This Arabidopsis thaliana enzyme (UGlcAE1) catalyzes the epimerization of UDP-α-D-glucuronate (UDP-GlcA) to UDP-α-D-galacturonate (UDP-GalA). The dimeric protein is encoded by the UGlcAE1 gene. Expression of the full-length gene in E.colifails to produce an active enzyme. It was postulated that the hydrophobic putative N-terminal transmembrane domain results in un- or misfolding of the protein in inclusion bodies [Gu04]. A partially purified recombinant UGlcAE1Δ1-64, lacking the transmembrane domain, however, could be expressed in E.coli and was shown to have a UDP-GlcA 4-epimerase catalytic activity [Gu04]. The reaction is reversible, but favours the formation of UDP-GalA over UDP-GlcA with an equilibrium constant of approximately 1.9. The enzyme does not require NAD+ or metal ions for activity, and maintains maximum activity in the presence of EDTA. The enzyme has a broad pH range (6.4 to 8.2) centered around 7.4-7.6. Activity is completely abolished at pH values lower than 4 and higher than 9.5 in phosphate buffer [Gu04]. The temperature range is also broad with enzyme activity between 25?C and 55?C with maximal activity between 30?C and 42?C. UDP-glucose and UDP-galactose had no inhibitory effect while UDP-xylose, UDP-arabinose and UDP were strong inhibitors.

Molecular Weight of Polypeptide: 43.5 kD (from nucleotide sequence)

Molecular Weight of Multimer: 88 kD (experimental) [Gu04]

Unification Links: Entrez:AAT06796 , ModBase:O22141 , PhylomeDB:O22141 , Pride:O22141 , Protein Model Portal:O22141 , SMR:O22141 , String:3702.AT2G45310.1-P , Swiss-Model:O22141 , TAIR:AT2G45310 , UniProt:O22141

Relationship Links: Entrez-Nucleotide:PART-OF:AY594693 , InterPro:IN-FAMILY:IPR001509 , InterPro:IN-FAMILY:IPR008089 , InterPro:IN-FAMILY:IPR016040 , Pfam:IN-FAMILY:PF01370 , Prints:IN-FAMILY:PR01713

Gene-Reaction Schematic: ?


Enzymatic reaction of: UDP-D-glucuronic acid 4-epimerase

EC Number: 5.1.3.6

UDP-α-D-glucuronate <=> UDP-α-D-galacturonate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

In Pathways: UDP-sugars interconversion , UDP-D-galacturonate biosynthesis I (from UDP-D-glucuronate)

Inhibitors (Unknown Mechanism): UDP-α-D-xylose [Gu04] , UDP [Gu04] , UDP-L-arabinose [Gu04] , potassium chloride [Gu04] , sodium chloride [Gu04]

Primary Physiological Regulators of Enzyme Activity: UDP-α-D-xylose , UDP , UDP-L-arabinose

Kinetic Parameters:

Substrate
Km (μM)
Citations
UDP-α-D-glucuronate
720.0
[Gu04]

T(opt): 36 °C [Gu04]

pH(opt): 7.5 [Gu04]


References

Gu04: Gu X, Bar-Peled M (2004). "The biosynthesis of UDP-galacturonic acid in plants. Functional cloning and characterization of Arabidopsis UDP-D-glucuronic acid 4-epimerase." Plant Physiol 136(4);4256-64. PMID: 15563616


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 Wed Nov 26, 2014, BIOCYC14B.