scholarly journals THE EFFECTS OF RIBONUCLEASE ON THE RIBONUCLEIC ACID AND ENZYME ACTIVITIES OF MICROSOMES ISOLATED FROM RAT LIVER HOMOGENATES

1954 ◽  
Vol 2 (5) ◽  
pp. 401-406 ◽  
Author(s):  
ALEX B. NOVIKOFF ◽  
JEAN RYAN ◽  
ESTELLE PODBER
Keyword(s):  
Rat Liver ◽  
Ribonucleic Acid ◽  
Enzyme Activities ◽  
Liver Homogenates

scholarly journals Hepatic Golgi fractions resolved into membrane and content subfractions.

1982 ◽  
Vol 92 (3) ◽  
pp. 822-832 ◽  
Author(s):  
K E Howell ◽  
G E Palade
Keyword(s):  
Electron Microscopy ◽  
Rat Liver ◽  
Enzyme Activities ◽  
Degree Of Contamination ◽  
Golgi Membranes ◽  
Membrane Enzyme ◽  
Biochemical Assays ◽  
The Reformation ◽  
Liver Homogenates

Golgi fractions isolated from rat liver homogenates have been resolved into membrane and content subfractions by treatment with 100 mM Na2CO3 pH 11.3. This procedure permitted extensive extraction of content proteins and lipoproteins, presumably because it caused an alteration of Golgi membranes that minimized the reformation of closed vesicles. The type and degree of contamination of the fractions was assessed by electron microscopy and biochemical assays. The membrane subfraction retained 15% of content proteins and lipids, and these could not be removed by various washing procedures. The content subfraction was contaminated by both membrane fragments and vesicles and accounted for 5 to 10% of the membrane enzyme activities of the original Golgi fraction. The lipid compositions of the subfractions was determined, and the phospholipids of both membrane and content were found to be uniformly labeled with [33P]phosphate administered in vivo.

Specific incorporation of adenosine-5′-phosphate-32P into ribonucleic acid in rat liver homogenates

1956 ◽  
Vol 20 ◽  
pp. 445-446 ◽  
Author(s):  
Charles Heidelberger ◽  
Eberhard Harbers ◽  
Kenneth C. Leibman ◽  
Y. Takagi ◽  
Van R. Potter
Keyword(s):  
Rat Liver ◽  
Ribonucleic Acid ◽  
Liver Homogenates

scholarly journals Effect of chloramphenicol on ribonucleic acid synthesis in liver cells in suspension

1965 ◽  
Vol 97 (1) ◽  
pp. 67-73 ◽  
Author(s):  
ST Jacob ◽  
PM Bhargava
Keyword(s):  
Rat Liver ◽  
Liver Cell ◽  
Ribonucleic Acid ◽  
Acid Synthesis ◽  
Inhibitory Effect ◽  
Cell Suspensions ◽  
Perfused Rat Liver ◽  
Tissue Slices ◽  
Hepatic Cells ◽  
Liver Homogenates

1. Chloramphenicol has a stimulatory effect on the incorporation of radioactive phosphate into the RNA of perfused rat-liver slices, whole liver homogenates or the liver-cell suspensions, and no effect on the incorporation of [(14)C]adenine and [(14)C]uracil into the RNA of the tissue slices. 2. Chloramphenicol completely inhibits the incorporation of labelled adenine and uracil into the RNA of the cell suspensions, or into the RNA of homogenates derived from the whole liver tissues. 3. Chloramphenicol has at most a slight inhibitory effect on the transport of labelled adenine or uracil in the hepatic cells in suspension; in the slices, the transport of these bases is not inhibited at all. 4. The above observations indicate that: (a) unlike the tissue slices, hepatic cells in suspension are permeable to chloramphenicol; (b) in the presence of chloramphenicol, for reasons that are not clear, the conversion of the base into the appropriate nucleotide does not proceed.

scholarly journals Subcellular distribution of pyruvate (glyoxylate) aminotransferases in rat liver

1978 ◽  
Vol 170 (1) ◽  
pp. 173-175 ◽  
Author(s):  
T Noguchi ◽  
Y Minatogawa ◽  
Y Takada ◽  
E Okuno ◽  
R Kido
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Enzyme Activities ◽  
Particulate Fraction ◽  
Aminotransferase Activity ◽  
Liver Homogenates ◽  
Glucagon Injection ◽  
Glyoxylate Aminotransferase

The distribution of pyruvate (glyoxylate) aminotransferases in the particulate fraction of rat liver homogenates was examined by centrifugation in a sucrose density graident. Aminotransferase activities towards serine, phenylalanine and histidine with pyruvate and those towards phenylalanine and histidine with glyoxylate were nearly identically distributed. Some 50-55% of the particulate activity was localized in the peroxisomes and the remainder in the mitochondria. Most of alanine-glyoxylate aminotransferase activity was localized in the mitochondria, with some activity in the peroxisomes. Glucagon injection resulted in increases of these enzyme activities in the mitochondria, but not in the peroxisomes.

REGULATION OF THE ACTIVITIES OF THE ENZYMES INVOLVED IN THE METABOLISM OF STEROID HORMONES IN RAT LIVER: THE EFFECT OF 19-NORTESTOSTERONE AND THE INFLUENCE OF CYPROTERONE ACETATE ON THE ACTION OF TESTOSTERONE AND 5α-DIHYDROTESTOSTERONE

1974 ◽  
Vol 77 (2) ◽  
pp. 287-297 ◽  
Author(s):  
Rüdiger Ghraf ◽  
Edmund Rodney Lax ◽  
Hanns-Georg Hoff ◽  
Herbert Schriefers
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Rat Liver ◽  
Enzyme Activities ◽  
Cyproterone Acetate ◽  
Hydroxysteroid Dehydrogenase ◽  
Seminal Vesicles ◽  
Normal Male ◽  
Steroid Hydroxylases ◽  
Drug Leads

ABSTRACT The androgens testosterone and 5α-dihydrotestosterone, the anabolic drug 19-nortestosterone and the anti-androgen cyproterone acetate were investigated with regard to their modifying action on the sexual differentiation of the activities of rat liver enzymes involved in steroid hormone metabolism. The activities of the enzymes (Δ4-5α-hydrogenase, 20-ketoreductase, 3α-and 3β-hydroxysteroid dehydrogenase, NAD- and NADP-dependent Δ4-3β-hydroxysteroid dehydrogenase, total steroid hydroxylases, 7α- and 16α-hydroxylase) were determined in cell-free liver fractions of male animals castrated on day 25 of life and killed on day 90; and of castrated animals which, from day 75 to 89 received daily sc injections (0.3 mg/100 g body weight) of the anabolic drug or the androgen only or in combination with cyproterone acetate (3 mg/100 g body weight). With the exception of 7α-hydroxylase castration leads to a feminization of the enzyme activity pattern. However, the degree of feminization varies from enzyme to enzyme. The administration of testosterone or of 5α-dihydrotestosterone reverses the effect of castration. With 5α-dihydrotestosterone activity values were reached which in some cases were significantly higher than those obtained with testosterone. Although both androgens restored the enzyme activities to the normal male values, neither androgen was able to compensate for the weight loss of the seminal vesicles in the dose administered. The administration of 19-nortestosterone in the same dose as testosterone is only 30 % as effective in restoring the weight loss of the seminal vesicles, but leads to identical activities of Δ4-5α-hydrogenase and of hydroxysteroid dehydrogenases as are found for testosterone. 19-Nortestosterone is without influence on the activities of total steroid hydroxylases and of 16α-hydroxylase. 16α-Hydroxylase is the only enzyme in which the activity enhancing effects of testosterone or of 5α-dihydrotestosterone can be completely blocked by the simultaneous administration of the anti-androgen cyproterone acetate. In all other enzyme activities the anti-androgen does not interfere with the effect of the androgens although it blocks their action on the weight restitution of the seminal vesicles by 60–70 %. 7α-Hydroxylase does not exhibit any androgen dependency. Neither castration nor the subsequent administration of the two androgens, or of the anabolic drug leads to any alterations in activity. However, it is interesting to note that the administration of cyproterone acetate does cause an increase in activity.

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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