scholarly journals Substrate Specificity of Mammalian D-Glucuronolactone Dehydrogenase

1973 ◽  
Vol 26 (4) ◽  
pp. 839 ◽  
Author(s):  
PG Tonkes ◽  
CA Marsh
Keyword(s):  
Substrate Specificity ◽  
Rat Liver ◽  
Soluble Fraction ◽  
Male Rat ◽  
Liver Homogenates

The NAD+-dependent D-glucuronolactone dehydrogenase from the soluble fraction of male rat liver homogenates was purified 350-fold with an overall recovery of 11 %.

Substrate specificity of iodothyronine 5′-deiodinase in rat liver homogenates and its requirements of divalent cations in vitro

Life Sciences ◽  
1986 ◽  
Vol 38 (24) ◽  
pp. 2231-2238 ◽  
Author(s):  
Shinya Kobayshi ◽  
Yan Gao ◽  
Richard L. Ong ◽  
Constance S. Pittman
Keyword(s):  
Substrate Specificity ◽  
Rat Liver ◽  
Divalent Cations ◽  
Liver Homogenates

INTRACELLULAR DISTRIBUTION OF PHOSPHOMONOESTERASES IN RAT LIVER HOMOGENATE

1954 ◽  
Vol 32 (1) ◽  
pp. 383-394 ◽  
Author(s):  
Claude Allard ◽  
Gaston de Lamirande ◽  
Hugo Faria ◽  
Antonio Cantero
Keyword(s):  
Acid Phosphatase ◽  
Rat Liver ◽  
Mouse Liver ◽  
Soluble Fraction ◽  
Liver Homogenate ◽  
Mitochondrial Fraction ◽  
Nuclear Fraction ◽  
Absolute Requirement ◽  
Rat Liver Cells ◽  
Liver Homogenates

Acid phosphatase or phosphomonoesterase II activity of rat and mouse liver homogenates, prepared in 0.25 M sucrose, was found mainly in the cytoplasmic granules. Since the small percentage of activity of the nuclear fraction activity could be explained by the presence of mitochondria (which were actually counted in this fraction) it is concluded that rat and mouse liver nuclei do not contain acid phosphatase activity.A rather broad range of acid phosphatase activity was observed in rat and mouse livers depending on the time elapsed between the preparation of homogenate and the activity determinations. However, a preincubation of the tissues or isolated fractions at 37° C. for 60 min. was sufficient to increase the activity to an optimal value, and thus eliminate variations due to the latency of this enzyme.Alkaline phosphatase or phosphomonoesterase I activity was also found to be latent in rat liver homogenates. The phenomenon was less apparent than for acid phosphatase and seemed to depend mostly on the nature of the buffer employed in the assay system.Some evidence for the presence of two forms of alkaline phosphatase in rat liver cells is presented. One form of the enzyme was found to have an absolute requirement of magnesium for activity and was present in the soluble fraction, whereas the other which was not activated by magnesium seemed firmly linked to the nuclei and microsomes and was absent in the soluble fraction. The activity in the mitochondrial fraction was small and seemed of doubtful significance.

INTRACELLULAR DISTRIBUTION OF PHOSPHOMONOESTERASES IN RAT LIVER HOMOGENATE

1954 ◽  
Vol 32 (4) ◽  
pp. 383-394 ◽  
Author(s):  
Claude Allard ◽  
Gaston de Lamirande ◽  
Hugo Faria ◽  
Antonio Cantero
Keyword(s):  
Acid Phosphatase ◽  
Rat Liver ◽  
Mouse Liver ◽  
Soluble Fraction ◽  
Liver Homogenate ◽  
Mitochondrial Fraction ◽  
Nuclear Fraction ◽  
Absolute Requirement ◽  
Rat Liver Cells ◽  
Liver Homogenates

Acid phosphatase or phosphomonoesterase II activity of rat and mouse liver homogenates, prepared in 0.25 M sucrose, was found mainly in the cytoplasmic granules. Since the small percentage of activity of the nuclear fraction activity could be explained by the presence of mitochondria (which were actually counted in this fraction) it is concluded that rat and mouse liver nuclei do not contain acid phosphatase activity.A rather broad range of acid phosphatase activity was observed in rat and mouse livers depending on the time elapsed between the preparation of homogenate and the activity determinations. However, a preincubation of the tissues or isolated fractions at 37° C. for 60 min. was sufficient to increase the activity to an optimal value, and thus eliminate variations due to the latency of this enzyme.Alkaline phosphatase or phosphomonoesterase I activity was also found to be latent in rat liver homogenates. The phenomenon was less apparent than for acid phosphatase and seemed to depend mostly on the nature of the buffer employed in the assay system.Some evidence for the presence of two forms of alkaline phosphatase in rat liver cells is presented. One form of the enzyme was found to have an absolute requirement of magnesium for activity and was present in the soluble fraction, whereas the other which was not activated by magnesium seemed firmly linked to the nuclei and microsomes and was absent in the soluble fraction. The activity in the mitochondrial fraction was small and seemed of doubtful significance.

Uptake, metabolism and subcellular distribution of [125I]T4 in calf thyroid slices

1984 ◽  
Vol 105 (3) ◽  
pp. 341-349 ◽  
Author(s):  
G. D. Chazenbalk ◽  
D. L. Kleiman de Pisarev ◽  
G. J. Juvenal ◽  
M. A. Pisarev
Keyword(s):  
Rat Liver ◽  
Paper Chromatography ◽  
Subcellular Distribution ◽  
Inhibitory Action ◽  
Soluble Fraction ◽  
Temperature Dependent ◽  
Liver Slices ◽  
Liver Homogenates

Abstract. Previous work from our laboratory has shown that iodothyronines have a direct inhibitory action on the thyroid. In the present studies the uptake, metabolism and subcellular distribution of labelled thyroxine were analyzed. The entry of this hormone reaches a plateau after 15–20 min incubation and is temperature-dependent. The T/M values for T4 were much lower than those of labelled T3 and the curve was different from that obtained with [125I]. The influence of a series of compounds on the T/M values for thyroxine was studied. KI, T3, IOP PTU and MMI were without effect. Absence of Ca++ in the buffer, or addition of KClO4 or ouabain caused a slight decrease, while TSH produced a stimulation in the T/M ratio. Calf thyroid slices dehalogenated thyroxine, producing both T3 and rT3. TSH increased the generation of these two compounds. Neither PTU nor IOP altered the production of T3 and rT3 significantly. The lack of effect of IOP on T3 and rT3 generation was confirmed in calf thyroid homogenates. However, and in agreement with previous reports, IOP significantly decreased production of both triiodothyronines in rat liver slices and in rat liver homogenates. When the subcellular distribution of labelled thyroxine was examined most of the radioactivity appeared in the soluble fraction and less than 1 % was present in purified nuclei. The addition of unlabelled thyroxine to the slices only caused a significant displacement in the radioactivity of purified nuclei. The presence of labelled thyroxine in the nuclei was confirmed by paper chromatography.

Differences in cholesterol oxidation and biosynthesis in liver of male and female rats

1961 ◽  
Vol 200 (3) ◽  
pp. 519-522 ◽  
Author(s):  
David Kritchevsky ◽  
Ezra Staple ◽  
Joseph L. Rabinowitz ◽  
Michael W. Whitehouse
Keyword(s):  
Rat Liver ◽  
Sodium Acetate ◽  
Liver Mitochondria ◽  
Female Rats ◽  
Male Rats ◽  
Cholesterol Oxidation ◽  
Male Rat ◽  
Rat Liver Mitochondria ◽  
Oxidized Cholesterol ◽  
Liver Homogenates

Female rat liver mitochondria oxidized cholesterol-26-C14 and sodium pyruvate-2-C14 to C14O2 to a much greater extent (per mg N) than did male rat liver mitochondria. Mitochondrial preparations from livers of castrated, estrogenized or castrated-estrogenized male rats all oxidized cholesterol-26-C14 to a greater extent than did liver preparations from normal male rats. No differences were observed in the oxidation of sodium octanoate-1-C14. The serum and liver cholesterol levels of the feminized rats were higher than those of the intact males. Biosynthesis of cholesterol from sodium acetate-2-C14 by male rat liver homogenates was significantly lower than biosynthesis by liver homogenates from normal female rats or gonadectomized rats of both sexes. The rate of biosynthesis from mevalonic acid-2-C14 by liver homogenates from castrated male rats was much higher than in homogenates of oophorectomized females or intact males or females. Differences in sex or gonadectomy had no effect on biosynthesis of fatty acids from sodium acetate-2-C14.

scholarly journals THE INCORPORATION OF THE CARBOXYL CARBON FROM ACETATE INTO CHOLESTEROL BY RAT LIVER HOMOGENATES

1954 ◽  
Vol 206 (1) ◽  
pp. 471-481 ◽  
Author(s):  
Ivan D. Frantz ◽  
Nancy L.R. Bucher ◽  
Henny S. Schneider ◽  
Naomi H. McGovern ◽  
Ruth Kingston
Keyword(s):  
Rat Liver ◽  
Liver Homogenates ◽  
Carboxyl Carbon
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