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discounted EARLY registration ends Dec 31, 2014
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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: luteolin-7-O-diglucuronide 4'-O-glucuronosyltransferase

Species: Secale cereale

Summary:
The biosynthesis of luteolin 7-O-[β-D-glucuronosyl-(1,2)-β-D-glucuronide]-4'-O-β-D-glucuronide is carried out by three position specific flavone glucuronosyltransferases namely luteolin 7-O-glucuronosyltransferase (LGT), luteolin 7-O-glucuronide-glucuronosyltransferase (LMT) and luteolin 7-O-diglucuronide-glucuronosyltransferase (LDT). Enzymatic assays using partially purified enzymes from Secale cereale (rye) primary leaves revealed that they are not only position specific but also substrate specific. Further these enzymes did not show significant activity towards UDP-glucose, UDP-galactose, or UDP-xylose as sugar donors. The luteolin 7-O-diglucuronide-glucuronosyltransferase (LDT) was shown to catalyze the glucuronidation of luteolin 7-O-β-D-diglucuronide to form luteolin 7-O-[β-D-glucuronosyl-(1,2)-β-D-glucuronide]-4'-O-β-D-glucuronide [Schulz88]. Using cellular fractionation LMT could be localized to the vacuole [Anhalt92].

Locations: vacuolar lumen

Molecular Weight of Polypeptide: 29.0 kD (experimental) [Schulz88 ]

pI: 4.75 [Schulz88]

Gene-Reaction Schematic: ?

GO Terms:

Cellular Component: GO:0005775 - vacuolar lumen Inferred from experiment [Anhalt92]

Credits:
Created 28-Apr-2009 by Karthikeyan AS , TAIR
Revised 29-Jan-2014 by Foerster H , Boyce Thompson Institute


Enzymatic reaction of: luteolin-7-O-diglucuronide 4'-O-glucuronosyltransferase

EC Number: 2.4.1.191

UDP-α-D-glucuronate + luteolin 7-O-β-D-diglucuronide <=> UDP + luteolin 7-O-[β-D-glucuronosyl-(1,2)-β-D-glucuronide]-4'-O-β-D-glucuronide + H+

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 favored in the direction shown.

In Pathways: luteolin triglucuronide biosynthesis

Inhibitors (Uncompetitive): UDP [Schulz88]

Inhibitors (Unknown Mechanism): luteolin [Schulz88]

Primary Physiological Regulators of Enzyme Activity: luteolin , UDP

Kinetic Parameters:

Substrate
Km (μM)
Vmax (µmol mg-1 min-1)
Citations
UDP-α-D-glucuronate
9.0
0.044
[Schulz88]
luteolin 7-O-β-D-diglucuronide
90.0
0.18
[Schulz88]

T(opt): 40 °C [Schulz88]

pH(opt): 7 [Schulz88]


References

Anhalt92: Anhalt S, Weissenbock G (1992). "Subcellular localization of luteolin glucuronides and related enzymes in rye mesophyll." Planta 187(1);83-8. PMID: 24177970

Schulz88: Schulz, M, Weissenböck, G (1988). "Three specific UDP-glucuronate-flavone-glucuronosyl-transferases from primary leaves of Secale cereale." Phytochemistry 27:1261-1267.


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 Tue Nov 25, 2014, biocyc13.