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

1968 ◽  
Vol 110 (4) ◽  
pp. 739-746 ◽  
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.

Effects of non-ionic and anionic detergents on lipid-associated tissue ferritin.

1988 ◽  
Vol 34 (1) ◽  
pp. 152-154
Author(s):  
B E Cham ◽  
P Roeser ◽  
A Nikles
Keyword(s):  
Guinea Pig ◽  
Liver Homogenate ◽  
Diisopropyl Ether ◽  
Detergent Concentration ◽  
Pig Liver ◽  
Ionic Detergents ◽  
Ionic Detergent ◽  
Anionic Detergents ◽  
Triton X ◽  
Guinea Pig Liver

Abstract Lipid-associated ferritin from homogenates of guinea pig liver is released from its conjugate(s) by incubation with the non-ionic detergents Triton X-100 and Nonidet P-40 but not by incubation with the anionic detergent deoxycholate. The amount of lipid-associated ferritin released from its conjugate(s) depends on the concentration of the non-ionic detergents. At a final non-ionic detergent concentration of about 20 g/L, all lipid-associated ferritin is released from its conjugate(s) in a liver homogenate. The amount released is identical with the amount of the lipid-associated ferritin obtained by extraction of the same liver homogenate with a mixture of butanol and diisopropyl ether.

scholarly journals Lipid synthesis in vivo by tissues of the maternal and foetal guinea pig

1976 ◽  
Vol 154 (1) ◽  
pp. 159-161 ◽  
Author(s):  
C T Jones ◽  
W Firmin
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Guinea Pig ◽  
Lipid Synthesis ◽  
Short Chain Fatty Acids ◽  
Adipose Tissues ◽  
Pig Liver ◽  
Foetal Liver ◽  
Guinea Pig Liver

The rate of lipid biosynthesis in vivo was determined in pregnant guinea pigs after maternal and foetal injections of 3H2O. Synthesis in the maternal tissues was low and in the foetal liver and adipose tissues relatively high. In the foetal liver it reached a peak at about two-thirds of gestation, whereas that in the foetal adipose tissue occurred later. These results were used to support the view that lipid synthesis in the foetal guinea-pig liver at two-thirds of gestation is largely from short-chain fatty acids, whereas in foetal adipose tissue glucose is probably the major substrate.

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

1968 ◽  
Vol 110 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Kim Ping Wong ◽  
Theodore L. Sourkes
Keyword(s):  
Guinea Pig ◽  
Glucuronic Acid ◽  
Enzymic Activity ◽  
Microsomal Preparation ◽  
Pig Liver ◽  
Related Compounds ◽  
Substrate Concentrations ◽  
Guinea Pig Liver

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.

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

1976 ◽  
Vol 157 (3) ◽  
pp. 667-673 ◽  
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.

scholarly journals Effect of physiological reducing compounds on the inactivation of tyrosine aminotransferase from guinea-pig liver*

1982 ◽  
Vol 205 (2) ◽  
pp. 265-269 ◽  
Author(s):  
D Di Cola ◽  
G Federici
Keyword(s):  
Guinea Pig ◽  
Reduced Glutathione ◽  
Tyrosine Aminotransferase ◽  
Enzyme Inactivation ◽  
Inactivation Rate ◽  
Physiological Concentration ◽  
Pig Liver ◽  
Microsomal Membranes ◽  
Guinea Pig Liver

1. Tyrosine aminotransferase from guinea-pig liver is inactivated at neutral pH by a factor localized in the microsomal fraction. The inactivation, independent of exogenous L-cysteine, is rapidly reversed by addition of dithiothreitol. 2. The effects of physiological reducing agents on the enzyme inactivation were investigated. L-Cysteine and L-cysteamine enhance the inactivation rate of the enzyme in the presence of microsomal membranes, and also they are able to bring about the loss in enzyme activity independently of microsomal action. Reduced glutathione, at physiological concentration, and NADPH decrease the inactivation rate. Other physiological reducing compounds, as well as oxidized glutathione and NADP+, are without effect. 3. Neither reduced glutathione nor NADPH, unlike dithiothreitol and mercaptoethanol, is able to restore the activity of partially inactivated tyrosine aminotransferase. 4. It is proposed that the intracellular concentration of reduced glutathione might modulate the rate of inactivation of the enzyme in vivo.

In vitro and in vivo studies on the metabolism of estrogens and their sulfates in guinea pigs

1977 ◽  
Vol 55 (4) ◽  
pp. 390-397 ◽  
Author(s):  
R. Hobkirk ◽  
D. J. Freeman ◽  
P. R. C. Harvey ◽  
Mona Nilsen ◽  
Barbara Jennings
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Mature Male ◽  
In Vivo Studies ◽  
Pig Liver ◽  
Male And Female ◽  
Estradiol 17Β ◽  
Guinea Pig Liver

Labelled estradiol-17β(E2) or estrone (E1), when incubated with guinea pig liver slices, is metabolized by two main pathways. Part of each substrate is converted to estrone-3-glucuronide and estradiol-3-glucuronide. A further part of each is metabolized to estradiol-3-sulfate (E23S) and estrone-3-sulfate (E13S), which are interconverted. The latter conjugate appears to be the substrate for a 16α-hydroxylase forming 16α-hydroxyestrone-3-sulfate (16αOHE13S). This, in turn, is further sulfurylated to yield 16α-hydroxyestrone-3,16-disulfate, accompanied by estriol-3,16-disulfate. A relatively small amount of tentatively identified '6-hydroxyestrone disulfate' accompanies these other two diconjugates. The guinea pig liver system suggests itself as a useful and relatively simple model for further study of 16α-hydroxylation of E13S. The use of the latter as a natural substrate in the system in vitro is supported by our observation that E13S and E23S are present in liver, kidney, blood, gallbladder bile, intestine, uterus, and placenta after injection of labelled E2 into mature male and female guinea pigs. Some evidence has been obtained for the disulfate fraction (above) in liver and bile after injection of labelled E1.

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

1977 ◽  
Vol 32 (11-12) ◽  
pp. 908-912 ◽  
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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