Separation and partial purification of two differentially inducible UDP-glucuronyltransferases from rat liver

supporting

confidence: 58%

Section: Discussionmentioning

confidence: 64%

Separation of oestrone UDP-glucuronyltransferase and p-nitrophenol UDP-glucuronyltransferase activities

Tukey¹,

Billings²,

Tephly³

1978

“…They may reflect two or more enzyme proteins, or a single enzyme protein whose specificity depends on a changing lipid environment. del Villar et al (1975) claim to have separated two fractions from rat liver which respectively glucuronidate 4-nitrophenol and morphine, and Bock et al (1977) have separated, also from rat liver, protein with transferase activity towards morphine from protein with activity towards both morphine and 1-naphthol. In each case, the proposed physical heterogeneity of the partly purified transferase activity is consistent with our division of functional heterogeneity.…”

Section: Discussionmentioning

confidence: 99%

Functional heterogeneity of UDP-glucuronosyltransferase as indicated by its differential development and inducibility by glucocorticoids. Demonstration of two groups within the enzyme's activity towards twelve substrates

Wishart¹

1978

170

1. UDP-glucuronosyltransferase activity towards 12 substrates has been assessed in rat liver during the perinatal period. 2. Between days 16 and 20 of gestation, enzyme activities towards the substrates 2-aminophenol, 2-aminobenzoate, 4-nitrophenol, 1-naphthol, 4-methylumbelliferone and 5-hydroxytryptamine (the 'late foetal' group) surge to reach adult values, while activities towards bilirubin, testosterone, beta-oestradiol, morphine, phenolphthalein, and chloramphenicol (the 'neonatal' group) remain negligible or at less than 10% of adult values. 3. By the second postnatal day, enzyme activities towards the neonatal group have attained, or approached adult values. 4. Dexamethasone precociously stimulates in 17-day foetal liver in utero transferase activities in the late foetal, but not the neonatal group. A similar inductive pattern is found for 15-day foetal liver in organ culture. 5. It is suggested that foetal glucocorticoids, whose synthesis markedly increases between days 16 and 20 of gestation, are responsibile for triggering the simultaneous surge of all the hepatic UDP-glucuronosyltransferase activities in the late foetal group. The neonatal group of activities apparently require a different or additional stimulus for their appearance. 6. The relationship of these two groups of transferase activities to other similar groups observed during induction by xenobiotics and enzyme purification is discussed.

“…Bock et al (1977) have demonstrated the separation and purification of 1-naphthol and morphine glucuronyltransferase activities. Gorski & Kasper (1977) and Burchell (1977) achieved considerable purification ofa UDP-glucuronyltransferase activity, but confined their studies to p-nitrophenol glucuronyltransferase activity.…”

mentioning

confidence: 99%

Phospholipid-dependence of oestrone UDP-glucuronyltransferase and p-nitrophenol UDP-glucuronyltransferase

Tukey¹,

Billings²,

Autor³

et al. 1979

Hepatic UDP-glucuronyltransferase activity was resolved into two fractions, one exhibiting oestrone glucuronyltransferase activity and the other exhibiting p-nitrophenol glucuronyltransferase activity. Hydroxyapatite-column chromatography removed greater than 95 % of the phospholipids from both preparations. The partially purified delipidated enzymes were essentially devoid of catalytic activity, but activities were restored by the addition of phospholipids or phosphatidylcholine mixtures containing various saturated and unsaturated fatty acids. Both oestrone andp-nitrophenol glucuronyltransferase activities were reconstituted to similar degrees with the phosphatidylcholine mixtures. When purified phospholipids were tested, phosphatidylcholine and lysophosphatidylcholine were most effective in restoring activity, whereas phosphatidylethanolamine was the least effective. These results further suggest that oestrone and p-nitrophenol UDP-glucuronyltransferases are dependent on phospholipids for their activity.