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

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.

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