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.

DNA Polymerase Activity in the Nuclei of Developing Rat Brain and Liver

1972 ◽  
Vol 50 (2) ◽  
pp. 186-189 ◽  
Author(s):  
M. R. V. Murthy ◽  
A. D. Bharucha
Keyword(s):  
Rat Brain ◽  
Dna Polymerase ◽  
Soluble Fraction ◽  
Growth Period ◽  
Polymerase Activity ◽  
Newborn Rat ◽  
A Value ◽  
Rat Brain And Liver ◽  
Dna Contents ◽  
Developing Rat

The level of DNA polymerase activity per tissue in the soluble fraction (NS) of rat brain nuclei underwent a twofold increase during the first 2 weeks after birth and then declined steeply over the next 10 weeks to a value only one-third ofthat in the newborn. In contrast to brain, the enzyme activity per liver increased continuously from birth up to 12 weeks of age (10-fold). The DNA contents of these tissues appear to be quantitatively related to the DNA polymerase activities in the respective NS fractions. These preparations did not phosphorylate thymidylate to TTP, but could convert the other three complementary deoxynucleotides to the triphosphate level. This latter activity was highest in the NS fraction of the newborn rat brain and decreased drastically with growth. In the corresponding fraction of liver, the activity remained relatively stable throughout the growth period tested.

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.

KINETIK UND CHARAKTERISIERUNG DER ÖSTRADIOLSENSITIVEN 17β-HYDROXYSTEROIDDEHYDROGENASEN IN DER MENSCHLICHEN LEBER

1971 ◽  
Vol 67 (3) ◽  
pp. 473-482 ◽  
Author(s):  
K.-P. Littmann ◽  
H. Gerdes ◽  
G. Winter
Keyword(s):  
Human Liver ◽  
Microsomal Fraction ◽  
Soluble Fraction ◽  
Late Pregnancy ◽  
Hydroxysteroid Dehydrogenase ◽  
Total Activity ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Hydroxysteroid Dehydrogenases ◽  
Km Value

ABSTRACT NAD+- and NADP + -linked 17β-hydroxysteroid dehydrogenases from human liver preparations are able to convert 17β-oestradiol to oestrone as well as testosterone to androstenedione without any substrate specificity. The NAD + -sensitive enzyme occurs in the microsomal fraction (14 % of the total activity) and in the soluble fraction (86 % of the total activity). The pH of maximum activity was 10.3. The Km value for 17β-oestradiol was 3.5 × 10−6 Mol/l in the microsomal and 9.8 × 10−6 Mol/l in the soluble fraction. In contrast the NADP + -linked 17β-hydroxysteroid dehydrogenase was only present in the soluble fraction with a pH-optimum at 9.8 and a Km for 17β-oestradiol of 5.1 × 10−6 Mol/l. Both NAD+-and NADP+-sensitive enzymes reached maximum activity at 45°C. These data indicate that 17β-hydroxy-C18-steroid dehydrogenases from human placenta and human pregnant blood serum which can be used as a test in late pregnancy are different from those of human liver.

scholarly journals Elongation of fatty acids by microsomal fractions from the brain of the developing rat

1975 ◽  
Vol 152 (3) ◽  
pp. 495-501 ◽  
Author(s):  
P J Brophy ◽  
D E Vance
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Rat Brain ◽  
Microsomal Fraction ◽  
Fatty Acid Biosynthesis ◽  
De Novo ◽  
Soluble Fraction ◽  
Residual Activity ◽  
Acid Biosynthesis ◽  
Malonyl Coa

Elongation of fatty acids by microsomal fractions obtained from rat brain was measured by the incorporation of [2-14C]malonyl-CoA into fatty in the presence of palmitoyl-CoA or stearoyl-CoA. 2. Soluble and microsomal fractions were prepared from 21-day-old rats; density gradient centrifugation demonstrated that the stearoyl-CoA elongation system was localized in the microsomal fraction whereas fatty acid biosynthesis de novo from acetyl-CoA occurred in the soluble fraction. The residual activity de novo in the microsomal fraction was attributed to minor contamination by the soluble fraction. 3. The optimum concentration of [2-14C]malonyl-CoA for elongation of fatty acids was 25 mum for palmitoyl-CoA or stearoyl-CoA, and the corresponding optimum concentrations for the two primer acyl-CoA esters were 8.0 and 7.2 muM respectively. 4. Nadph was the preferred cofactor for fatty acid formation from palmitoyl-CoA or stearoyl-CoA, although NADH could partially replace it. 5. The stearoyl-CoA elongation system required a potassium phosphate buffer concentration of 0.075M for maximum activity; CoA (1 MUM) inhibited this elongation system by approx. 30%. 6. The fatty acids formed from malonyl-CoA and palmitoyl-CoA had a predominant chain length of C18 whereas stearoyl-CoA elongation resulted in an even distribution of fatty acids with chain lengths of C20, C22 and C24. 7. The products of stearoyl-CoA elongation were identified as primarily unesterified fatty acids. 8. The developmental pattern of fatty acid biosynthesis by rat brain microsomal preparations was studied and both the palmitoyl-CoA and stearoyl-CoA elongation systems showed large increases in activity between days 10 and 18 after birth.

scholarly journals Identiy of brain alcohol dehydrogenase with liver alcohol dehydrogenase

1976 ◽  
Vol 153 (3) ◽  
pp. 561-566 ◽  
Author(s):  
R J Duncan ◽  
J E Kline ◽  
L Sokoloff
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rat Brain ◽  
Specific Activity ◽  
Liver Homogenate ◽  
Total Activity ◽  
Liver Alcohol Dehydrogenase ◽  
Rat Brain And Liver ◽  
Severe Liver Damage ◽  
Common Antigens ◽  
The Brain

A method for obtaining electrophoretically homogeneous rat liver alcohol dehydrogenase (EC 1.1.1.1) at a specific activity of 2-2.5 μmol/min per mg of protein is presented. Anti-sera prepared against the purified enzyme inhibit alcohol dehydrogenase by up to 75% and cause precipitation of virtually all the enzyme. The antisera were shown by immunoelectrophoresis of a partially purified liver homogenate to be specifically directed against alcohol dehydrogenase and were used to demonstrate that the alcohol dehydrogenases of rat brain and liver share common antigens. The total activity of alcohol dehydrogenase in rat brain homogenates is normally quite low, with as much as 10% of the total activity attributable to the activity in the blood contained within the brain; in cases of severe liver damage (induced experimentally with carbon tetrachloride) this contribution may rise to as much as 60%.

scholarly journals Enzymic synthesis of ether types of choline and ethanolamine phosphoglycerides by microsomal fractions from rat brain and liver

1977 ◽  
Vol 18 (1) ◽  
pp. 53-58
Author(s):  
A Radominska-Pyrek ◽  
J Strosznajder ◽  
Z Dabrowiecki ◽  
G Goracci ◽  
T Chojnacki ◽  
...  
Keyword(s):  
Rat Brain ◽  
Enzymic Synthesis ◽  
Ethanolamine Phosphoglycerides ◽  
Rat Brain And Liver

Respiration of Rat Brain and Liver at Temperatures above 37°C

1951 ◽  
Vol 24 (2) ◽  
pp. 163-166
Author(s):  
Robert L. Jasper ◽  
James W. Archdeacon
Keyword(s):  
Rat Brain ◽  
Rat Brain And Liver
Sign in / Sign up

Export Citation Format

Share Document