MetaCyc Enzyme: luteolin-7-O-diglucuronide 4'-O-glucuronosyltransferase

Species: Secale cereale

The biosynthesis of luteolin 7-O-[β-D-glucosyluronate-(1,2)-β-D-glucosiduronate]-4'-O-β-D-glucosiduronate 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-glucosyluronate-(1,2)-β-D-glucosiduronate]-4'-O-β-D-glucosiduronate [Schulz88a]. Using cellular fractionation LMT could be localized to the vacuole [Anhalt92].

Locations: vacuolar lumen

Molecular Weight of Polypeptide: 29.0 kD (experimental) [Schulz88a]

pI: 4.75 [Schulz88a]

Gene-Reaction Schematic

Gene-Reaction Schematic

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

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

Inferred from experiment

EC Number:

UDP-α-D-glucuronate + luteolin 7-O-β-D-diglucuronide → UDP + luteolin 7-O-[β-D-glucosyluronate-(1,2)-β-D-glucosiduronate]-4'-O-β-D-glucosiduronate + H+

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: luteolin triglucuronide biosynthesis

Inhibitors (Uncompetitive): UDP [Schulz88a] Inhibitors (Unknown Mechanism): luteolin [Schulz88a]

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 [Schulz88a]
luteolin 7-O-β-D-diglucuronide 90.0 0.18 [Schulz88a]

T(opt): 40 °C [Schulz88a]

pH(opt): 7 [Schulz88a]


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

Schulz88a: Schulz, M, Weissenböck, G (1988). "Three specific UDP-glucuronate-flavone-glucuronosyl-transferases from primary leaves of Secale cereale." Phytochemistry 27:1261-1267.

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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