scholarly journals Phospholipid content and activity of pure uridine diphosphate-glucuronyltransferase from rat liver

1978 ◽  
Vol 171 (3) ◽  
pp. 821-824 ◽  
Author(s):  
B Burchell ◽  
T Hallinan
Keyword(s):  
Enzyme Activity ◽  
Phospholipase C ◽  
Rat Liver ◽  
Phospholipid Content ◽  
Uridine Diphosphate

Rat liver phospholipids were radioactively labeled in vivo before purification of UDP-glucuronyltransferase to homogeneity. The pure enzyme contained very little phospholipid (approx. 0.7 mol of phospholipid/mol of protein). The solubilization detergent Lubrol 12A9 appeared to act as a phospholipid substitute, capable of supporting UDP-glucuronyltransferase activity. Phospholipase C did not inhibit the pure enzyme activity and pure UDP-glucuronyltransferase was stimulated by 40–100% by the addition of phospholipid dispersions.

scholarly journals The effect of phenobarbital on the submicrosomal distribution of uridine diphosphate glucuronyltransferase from rat liver

1970 ◽  
Vol 117 (2) ◽  
pp. 319-324 ◽  
Author(s):  
G. J. Mulder
Keyword(s):  
Enzyme Activity ◽  
Density Gradient ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Sucrose Density Gradient ◽  
Male Rats ◽  
Uridine Diphosphate ◽  
Triton X

1. The detergent Triton X-100 activates UDP glucuronyltransferase from rat liver in vitro six- to seven-fold with p-nitrophenol as substrate. The enzyme activity when measured in the presence of Triton X-100 is increased significantly by pretreatment of male rats with phenobarbital for 4 days (90mg/kg each day intraperitoneally). If no Triton X-100 is applied in vitro such an increase could not be shown. In all further experiments the enzyme activity was measured after activation by Triton X-100. 2. The Km of the enzyme for the substrate p-nitrophenol does not change on phenobarbital pretreatment. 3. When the microsomal fraction from the liver of untreated rats is subfractionated on a sucrose density gradient, 47% of the enzyme activity is recovered in the rough-surfaced microsomal fraction, which also has a higher specific activity than the smooth-surfaced fraction. 4. Of the increase in activity after the phenobarbital pretreatment 50% occurs in the smooth-surfaced fraction, 19% in the rough-surfaced fraction and 31% in the fraction located between the smooth- and rough-surfaced microsomal fractions on the sucrose density gradient. 5. The latency of the enzyme in vitro, as shown by the effect of the detergent Triton X-100, is discussed in relation to the proposed heterogeneity of UDP glucuronyltransferase.

scholarly journals Stimulation of defective Gunn-rat liver uridine diphosphate glucuronyltransferase activity in vitro by alkyl ketones

1979 ◽  
Vol 177 (3) ◽  
pp. 993-995 ◽  
Author(s):  
E N Lalani ◽  
B Burchell
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Wistar Rat ◽  
Uridine Diphosphate ◽  
Gunn Rat ◽  
Alkyl Ketone ◽  
Genetic Deficiency ◽  
Liver Homogenates ◽  
Stimulation Of

Addition of alkyl ketone (10mM) to Gunn-rat liver homogenates increased UDP-glucuronyltransferase activity towards 2-aminophenol by 10–20 fold, up to enhanced values of enzyme activity observed with similarly treated Wistar-rat liver homogenates. Alkyl ketones also activate the defective enzyme purified from Gunn-rat liver. This genetic deficiency of UDP-glucuronyltransferase activity is no longer apparent when assayed in the presence of alkyl ketones.

The relationship between Mg2+-stimulated ATPase activity and glycogen content in rat liver

1969 ◽  
Vol 47 (3) ◽  
pp. 339-345 ◽  
Author(s):  
B. Rubenstein ◽  
P. G. Scholefield
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Rat Liver ◽  
Glycogen Content ◽  
Phosphorylase Activity ◽  
Tumor Bearing ◽  
Physical Association ◽  
The Relationship

During starvation there is an increase in the ATPase activity of a postmitochondrial fraction of rat liver. The increase is relatively specific for ATP and there is no change in the Na+,K+-stimulated ATPase activity. A corresponding increase in ATPase activity is found on pretreatment of the rat with glucagon and in tumor-bearing animals. The increase has been correlated with increase in phosphorylase activity and decrease in glycogen content under in vivo and in vitro conditions. Treatment of fasted animals with glucose or sucrose restores the glycogen content and diminishes the ATPase activity to normal levels, but puromycin is without effect. It is proposed that a physical association of glycogen with Mg2+-stimulated ATPase activity prevents the enzyme activity from being expressed.

scholarly journals Precocious development of uridine diphosphate glucuronosyltransferase activity during organ culture of foetal rat liver in the presence of glucocorticoids

1977 ◽  
Vol 166 (2) ◽  
pp. 249-253 ◽  
Author(s):  
G J Wishart ◽  
M A Goheer ◽  
J E A Leakey ◽  
G J Dutton
Keyword(s):  
Rat Liver ◽  
Defined Medium ◽  
Transferase Activity ◽  
Uridine Diphosphate ◽  
Chemically Defined Medium ◽  
Foetal Rat ◽  
First Time ◽  
Precocious Development ◽  
Stimulation Of

1. Precocious development of mammalian UDP-glucuronosyltransferase (EC 2.4.1.1.7) induced by endogenous compounds of known chemical composition is reported for the first time. 2. This development occurs in cultured explants of foetal rat liver when exposed to corticosteroids possessing a pregn-4′-ene structure and a hydroxy or an oxo group at C-11. 3. Explants from 14-day foetuses cultured for 3 days in a chemically defined medium containing dexamethasone exhibited transferase activities towards o-aminophenol within adult male values. Those liver transferase activities attained in utero by 17 days were still negligible. 4. Evidence from several approaches indicated that the explants required glucocorticoids for expression of the transferase, not for maintenance of viability. 5. Glucocorticoid-dependent stimulation of transferase activity required incorporation of L-[14C]leucine into protein, as judged from the pulsing of cultures with cycloheximide. 6. The relevance of these culture experiments to the situation in vivo is discussed.

scholarly journals Retinyl phosphate mannose synthesis in rat liver membranes. Phospholipase sensitivity and phospholipid requirement

1983 ◽  
Vol 216 (3) ◽  
pp. 727-735
Author(s):  
Y Shidoji ◽  
C S Silverman-Jones ◽  
L M De Luca
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Phospholipase C ◽  
Rat Liver ◽  
Membrane Fraction ◽  
Inhibitory Effect ◽  
Synthetic Activity ◽  
Dolichyl Phosphate ◽  
Liver Membranes ◽  
Endogenous Lipids

A remarkable and immediate decrease in GDP-mannose:retinyl phosphate mannosyltransferase activity was found on pre-incubation of rat liver postnuclear membranes with phospholipase A2 or phospholipase C. Under the same conditions of pre-incubation (1 min at 37 degrees C) trypsin did not affect the enzyme activity, whereas pre-incubation for 30 min with trypsin and Pronase abolished enzyme activity. The lipid extract of untreated rat liver membranes partially restored enzyme activity after phospholipase treatment. Sphingomyelin was as active as the endogenous lipids. Other phospholipids were less active in the following order: phosphatidylcholine greater than phosphatidylethanolamine greater than phosphatidylinositol = phosphatidylserine. Dolichyl phosphate mannose synthesis was inhibited less (33%) by phospholipase C than was Ret-P-Man synthesis (98.5%) under identical conditions of incubation, which included 0.025% Triton. However, retinyl phosphate mannose synthesis by purified endoplasmic reticulum was found to be resistant to phospholipase C. Mixing experiments failed to demonstrate an inhibitory effect of the phospholipase-treated postnuclear membrane fraction on the synthetic activity of the endoplasmic reticulum, thus excluding the release of an inhibitory factor from the postnuclear membranes.

scholarly journals Some properties of the uridine diphosphate glucuronyltransferase activity synthesizing thio-β-d-glucuronides

1973 ◽  
Vol 131 (1) ◽  
pp. 139-147 ◽  
Author(s):  
H. P. A. Illing ◽  
G. J. Dutton
Keyword(s):  
Enzyme Activity ◽  
Phenolic Compounds ◽  
Organ Culture ◽  
Tissue Distribution ◽  
Glucuronic Acid ◽  
Uridine Diphosphate ◽  
Intracellular Location ◽  
Gunn Rats ◽  
Optimum Ph

1. Some properties of the UDP-glucuronyltransferase synthesizing thio-β-d-glucuronides were investigated and compared with those of the enzyme synthesizing the O-glucuronides of analogous phenols. 2. Enzyme activity was generally similar for both classes of substrate in tissue distribution, intracellular location, optimum pH, perinatal development and induction by organ culture or by phenobarbital. 3. Certain differences were noted between the two types of activity in behaviour on storage and on activation, in kinetic behaviour and in distribution between Wistar and Gunn rats; the Gunn rats were not deficient in hepatic UDP-glucuronyltransferase activity towards o-aminothiophenol. 4. These differences are no greater than those exhibited in the synthesis of various O-glucuronides; therefore thiolic substrates could compete in vivo with phenolic compounds for access to the UDP-glucuronyltransferase complex as well as for UDP-glucuronic acid.

scholarly journals Studies on cystathionase activity in rat liver and brain during development. Effects of hormones and amino acids in vivo

1973 ◽  
Vol 136 (4) ◽  
pp. 1011-1015 ◽  
Author(s):  
Kirsti Heinonen
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Rat Brain ◽  
High Activity ◽  
Rat Liver ◽  
Newborn Rats ◽  
Postnatal Rats

High activity of cystathionase was present in rat liver but only low amounts of activity in rat brain during development. Triamcinolone had no effect on liver cystathionase activity in foetuses but increased the enzyme activity significantly in postnatal rats. l-Thyroxine decreased liver cystathionase activity significantly in newborn rats; administration of pyridoxal 5′-phosphate did not prevent this effect. l-Methionine significantly increased liver cystathionase activity in newborn rats.

scholarly journals Studies on the purification of rat liver uridine diphosphate glucuronyltransferase

1977 ◽  
Vol 161 (3) ◽  
pp. 543-549 ◽  
Author(s):  
B Burchell
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Polyacrylamide Gel ◽  
Uridine Diphosphate ◽  
Enzyme Protein ◽  
Epoxide Hydratase

1. A stable, more highly purified, preparation of UDP-glucuronyltransferase was obtained than previously reported. 2. Enzyme activity towards o-aminophenyl and p-nitrophenyl was increased 43- and 46-fold respectively. 3. The final preparation contains only three staining polypeptide bands visible after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 4. The only known major accompanying protein appears to be epoxide hydratase. 5. The purified enzyme activity towards o-aminophenol can still be activated 3 fold by diethylnitrosamine. 6. On evidence from purification, o-aminophenol and p-nitrophenol appear to be glucuronidated by the same enzyme protein. The possible recognition of the UDP-glucuronyltransferase enzyme is discussed.

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