Glucuronidation of 3-O-methylnoradrenaline, harmalol and some related compounds

1. The following compounds were glucuronidated in the presence of UDP-glucuronic acid and a microsomal preparation made from guinea-pig liver: 14C-labelled 3-O-methyladrenaline, 3-O-methylnoradrenaline, 3-methoxytyramine and 4-hydroxy-3-methoxyphenethanol, as well as unlabelled harmalol and harmol. 2. [14C]Homovanillic (4-hydroxy-3-methoxyphenylacetic) acid was not a substrate for the microsomal glucuronyltransferase. 3. The Km values for harmalol and harmol were 0·69×10−4m and 0·50×10−4m respectively. 4. The Km values for UDP-glucuronic acid, in the presence of 14C-labelled 3-O-methylnoradrenaline, harmalol and harmol as aglycones, were 0·57×10−4m, 0·44×10−4m and 2·20×10−4m respectively. 5. Mg2+ added at 2·5–10mm activated glucuronyltransferase, with harmalol as substrate. Concentrations above 10mm inhibited the enzymic activity. 6. The overall, or net, transglucuronidating activity of microsomal preparations of the liver, with harmalol as substrate, was greatest for guinea pig, and very much lower for rabbit, mouse and rat.

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A rapid enzymic procedure for the determination of picomole amounts of UDP-glucuronic acid

Biochemical Journal ◽

10.1042/bj1890369 ◽

1980 ◽

Vol 189 (2) ◽

pp. 369-372 ◽

Cited By ~ 13

Author(s):

J Singh ◽

L R Schwarz ◽

F J Wiebel

Keyword(s):

Guinea Pig ◽

Glucuronic Acid ◽

Cultured Cells ◽

Cellular Protein ◽

Pig Liver ◽

Guinea Pig Liver

A simple microassay for the determination of UDP-glucuronic acid was developed on the basis of the formation of benzo[a]pyrene 3-glucuronide catalysed by UDP-glucuronyltransferase of guinea-pig liver. As little as 1-5 pmol of UDP-glucuronic acid was detectable in extracts of heat-denatured probes of liver or cultured cells equivalent to 10-50 micrograms of cellular protein.

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The properties of uridine diphosphate glucuronyltransferase(s) which catalyse the synthesis of steroid glucuronides in microsomal fractions from guinea-pig liver

Biochemical Journal ◽

10.1042/bj1570667 ◽

1976 ◽

Vol 157 (3) ◽

pp. 667-673 ◽

Cited By ~ 12

Author(s):

D Zakim ◽

D A Vessey

Keyword(s):

Guinea Pig ◽

Glucuronic Acid ◽

Large Family ◽

Uridine Diphosphate ◽

Bivalent Metal ◽

Pig Liver ◽

Bivalent Metal Ions ◽

Triton X ◽

Related Proteins ◽

Guinea Pig Liver

The properties of the UDP-glucuronyltransferase(s) of guinea-pig liver that catalyse the synthesis of steroid glucuronides were examined. There are many similarities between apparently different substrate-specific forms of these enzymes in that all are activated by bivalent metal ions, and all contain at least 2 thiol groups important for enzyme activity. On the other hand, there are significant differences between the enzymes conjugating steroids and those conjugating non-steroids. Only the latter are activated by UDP-N-acetylglucosamine, which enhances their relatively poor affinity for UDP-glucuronic acid. The steroid-conjugating forms of UDP-glucuronyltransferase are not activated by UDP-N-acetylglucosamine and have relatively high apparent affinities for UDP-glucuronic acid. The rate of glucuronidation of testosterone was inhibited by treatment with phospholipase A. Treatment with cholate or Triton X-100 did not enhance the rates of glucuronidation of any steroid tested. The data indicate several similarities between different forms of UDP-glucuronyltransferase, suggesting that there is a large family of related proteins. At the same time there are important differences in the parameters that modulate the rates of different glucuronidation reactions.

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The availability of carnitine acetyltransferase in mitochondria from guinea-pig liver and other tissues

Biochemical Journal ◽

10.1042/bj1100739 ◽

1968 ◽

Vol 110 (4) ◽

pp. 739-746 ◽

Cited By ~ 18

Author(s):

P. J. Barker ◽

N. J. Fincham ◽

D C Hardwick

Keyword(s):

Guinea Pig ◽

Glutamate Dehydrogenase ◽

Freeze Drying ◽

Enzymic Activity ◽

Carnitine Acetyltransferase ◽

Cell Cytoplasm ◽

Pig Liver ◽

Triton X ◽

Guinea Pig Liver

The carnitine acetyltransferase and glutamate dehydrogenase activities of guinea-pig liver and other tissues were estimated. Both enzymes are wholly mitochondrial, and can only be fully observed after disruption of the mitochondrion. Triton X-100 (0·1%) or freeze-drying revealed more activity than other methods tried. In mitochondria prepared and suspended in 0·25m-sucrose and in cell cytoplasm only small fractions of the total enzymic activity could be observed in guinea-pig liver: on average 7·5% of carnitine acetyltransferase and 5·5% of glutamate dehydrogenase. It is concluded that, in liver or mammary gland of goat, guinea pig or rat, little or no carnitine acetyltransferase is available in vivo to acetyl-CoA outside the mitochondrion.

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Biliary excretion of cyclohexylphenyl 4-[35S]sulphate in the guinea pig

Biochemical Journal ◽

10.1042/bj1760443 ◽

1978 ◽

Vol 176 (2) ◽

pp. 443-448

Author(s):

G M Powell ◽

A H Olavesen ◽

C G Curtis

Keyword(s):

Molecular Weight ◽

Guinea Pig ◽

Biliary Excretion ◽

Glucuronic Acid ◽

Intact Animal ◽

Relative Concentration ◽

Metabolic Fate ◽

Pig Liver ◽

Acid Conjugate ◽

Guinea Pig Liver

The metabolic fate and mode of excretion of cyclohexylphenyl 4-[35S]sulphate were studied in the guinea pig. Up to 54.8% of the dose appeared in the bile, the majority as unchanged ester. Substantial amounts of hydroxylated cyclohexylphenyl 4-[35S]sulphate were also excreted in the bile together with minor amounts of the corresponding glucuronic acid conjugate. When isolated guinea-pig livers were perfused with cyclohexylphenyl 4-[35S]sulphate the biliary components were the same as those in the intact animal, although the relative concentration of the hydroxylated derivative was significantly greater. When the hydroxylated derivative was re-injected into guinea pigs it was excreted almost entirely unchanged in the bile. However, in the rat, it was excreted in the bile as a glucuronic acid conjugate. These findings are discussed in relation to studies carried out in the rat [Hearse, Powell, Olavesen & Dodgson (1969) Biochem. Pharmacol. 18, 181–195] and to differences in enzyme activities in rat and guinea-pig liver. The results are also discussed in terms of the molecular-weight threshold for the excretion of anions in guinea-pig bile.

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Die Bedeutung der Homogenisationsart und -intensität für die Größe und Konstanz der Sauerstoffaufnahme von Meerschweinchen-Leberhomogenat / The Influence of Mode and Intensity of Homogenization on the Absolute Value and Stability of Oxygen Consumption of Guinea Pig Liver Homogenates

Zeitschrift für Naturforschung C ◽

10.1515/znc-1977-11-1205 ◽

1977 ◽

Vol 32 (11-12) ◽

pp. 908-912 ◽

Cited By ~ 5

Author(s):

H. J. Schmidt ◽

U. Schaum ◽

J. P. Pichotka

Keyword(s):

Oxygen Uptake ◽

Guinea Pig ◽

Measuring Time ◽

Pig Liver ◽

Absolute Value ◽

Modified Method ◽

Simultaneous Measurements ◽

Liver Homogenates ◽

The Absolute ◽

Guinea Pig Liver

Abstract The influence of five different methods of homogenisation (1. The method according to Potter and Elvehjem, 2. A modification of this method called Potter S, 3. The method of Dounce, 4. Homogenisation by hypersonic waves and 5. Coarce-grained homogenisation with the “Mikro-fleischwolf”) on the absolute value and stability of oxygen uptake of guinea pig liver homogenates has been investigated in simultaneous measurements. All homogenates showed a characteristic fall of oxygen uptake during measuring time (3 hours). The modified method according to Potter and Elvehjem called Potter S showed reproducible results without any influence by homogenisation intensity.

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Precision-cut Guinea-pig Liver Slices as a Tool for Studying the Toxicity of Volatile Anaesthetics

Alternatives to Laboratory Animals ◽

10.1177/026119299001800120.1 ◽

1990 ◽

Vol 18 (1_part_1) ◽

pp. 191-199

Author(s):

Hanan N. Ghantous ◽

Jeanne Fernando ◽

Scott E. Morgan ◽

A. Jay Gandolfi ◽

Klaus Brandel

Keyword(s):

Guinea Pig ◽

Rank Order ◽

Normal Liver ◽

Liver Slice ◽

Volatile Anaesthetics ◽

Pig Liver ◽

Liver Slices ◽

Guinea Pig Liver ◽

Krebs Henseleit Buffer

Cultured precision-cut liver slices retain normal liver architecture and physiological biochemical functions. Hartley male guinea-pig liver slices have proven to be a good model for studying the biotransformation and toxicity of halothane. This system was used to evaluate the biotransformation and toxicity of different volatile anaesthetics (halothane, enflurane, isoflurane and sevoflurane), and compare their effects to those of new anaesthetics (desflurane). Liver slices (250–300μm thick) were incubated in sealed roller vials, containing Krebs Henseleit buffer at 37°C under 95% O2:5% CO2 atmosphere. Volatile anaesthetics were delivered by volatilisation after pre-incubation for 1 hour to produce a constant concentration in the medium. Production of the metabolites, trifluroacetic acid and fluoride ion, was measured. Intracellular potassium ion content, protein synthesis and secretion were determined as indicators of viability of the slices. The rank order of biotransformation of anaesthetics by the liver slices was halothane >sevoflurane>isoflurane and enflurane>desflurane. The rank order of hepatotoxicity of these anaesthetics was halothane>isoflurane and enflurane>sevoflurane and desflurane. Halothane is the anaesthetic which is metabolised furthest and has the most toxic effect, while desflurane is the least metabolised anaesthetic and has the least toxicity. This in vitro cultured precision-cut liver slice system appears to be suitable for studying the biotransformation of volatile anaesthetics and correlating its role in the resulting toxicity.

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