Metabolism of deethylatrazine, deisopropylatrazine, and hydroxyatrazine by the soluble fraction (105000g) from goose liver homogenates

1980 ◽  
Vol 28 (6) ◽  
pp. 1083-1085 ◽  
Author(s):  
Thomas S. Foster ◽  
Shahamat U. Khan ◽  
M. Humayoun Akhtar
Keyword(s):  
Soluble Fraction ◽  
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.

Depolymerization of polyadenylic acid by subcellular fractions of rat brain and liver

1969 ◽  
Vol 47 (3) ◽  
pp. 283-289 ◽  
Author(s):  
M. R. V. Murthy ◽  
A. D. Bharucha ◽  
C. Raynaud-Jammet
Keyword(s):  
Rat Brain ◽  
Microsomal Fraction ◽  
Soluble Fraction ◽  
Total Activity ◽  
Relative Increase ◽  
Nuclear Fraction ◽  
Polyadenylic Acid ◽  
Rat Brain And Liver ◽  
Liver Homogenates ◽  
Maximum Increment

Rat brain and liver homogenates depolymerized polyadenylic acid when added to a reaction mixture containing this polynucleotide. The activity in the homogenate declined progressively with the age of the tissues. This was reflected in a parallel reduction in the activity of the soluble fraction. In brain, the activity in the nuclear fraction also declined in the adult to half the level of the newborn. In contrast, liver nuclei had approximately the same activity at all stages of growth.With advancement in age, an increasingly greater proportion of the total activity of the tissues was contained in the nuclear fraction, while at the same time the proportion of activity in the soluble fraction decreased. The proportion of activity contained in the mitochondrial–microsomal fraction also increased with growth in brain, with the maximum increment in activity occurring after 8 weeks of age. In liver, there was actually a decrease of activity in this fraction during the same period. At all ages, the mitochondrial–microsomal fraction of brain contained a higher proportion of activity and the nuclear fraction of brain contained a lower proportion of activity compared to corresponding fractions of liver. The presence of polyadenylic acid degrading activity in these fractions and its relative increase with age may indicate a changing emphasis in the pattern of RNA metabolism during growth; for example, a higher rate of RNA synthesis in the young and a higher rate of RNA turnover in the adult.When the soluble fraction of rat brain was dialyzed, the polyadenylic acid degrading activity of this fraction was stimulated by the addition of inorganic orthophosphate. Brain and liver homogenates also mediated an ADP – inorganic phosphate exchange reaction which was highest in the newborn and decreased rapidly with age. These observations indicate that at least a part of the polyadenylic acid degrading activity in brain and liver extracts may be due to phosphorolytic action.

Metabolism of atrazine by the soluble fraction (105000g) from chicken liver homogenates

1979 ◽  
Vol 27 (2) ◽  
pp. 300-302 ◽  
Author(s):  
Thomas S. Foster ◽  
Shahamat U. Khan ◽  
M. Humayoun Akhtar
Keyword(s):  
Soluble Fraction ◽  
Chicken Liver ◽  
Liver Homogenates

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.

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