scholarly journals Inhibition by α-amanitin of ribonucleic acid polymerase solubilized from rat liver nuclei

1970 ◽  
Vol 116 (2) ◽  
pp. 177-180 ◽  
Author(s):  
F. Novello ◽  
L. Fiume ◽  
F. Stirpe
Keyword(s):  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Rat

1. α-Amanitin inhibits in vitro the RNA polymerase solubilized from isolated rat liver nuclei. 2. In contrast with previous observations with whole nuclei, the inhibition occurs approximately to the same extent in the presence and in the absence of ammonium sulphate. 3. Evidence is presented that the toxin acts by interacting with the enzyme itself and not with DNA or other components.

scholarly journals The effects of copper and other ions on the ribonucleic acid polymerase activity of isolated rat liver nuclei

1969 ◽  
Vol 111 (1) ◽  
pp. 115-119 ◽  
Author(s):  
F. Novello ◽  
F. Stirpe
Keyword(s):  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Ribonucleic Acid ◽  
Polymerase Activity ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Liver ◽  
Isolated Rat

1. The effects of various ions on the Mg2+- and Mn2+/ammonium sulphate-activated RNA polymerase activities of isolated liver nuclei were studied. 2. The Mg2+-activated RNA polymerase reaction was inhibited by more than 60% by Cd2+, SeO32−, Be2+, Cu2+, Co2+, Ca2+ and La3+, all at 1mm concentrations. 3. The Mn2+/ammonium sulphate-activated RNA polymerase reaction was strongly inhibited by Hg2+, Cd2+, Cu2+ and Ag+. The effect of Hg2+, Cd2+ and Ag+ was relieved by cysteine or mercaptoethanol. 4. Inhibition by Cu2+ was not affected by addition of DNA, and was relieved only partially by EDTA or histidine. 5. No changes of RNA polymerase activities were observed in nuclei isolated from the liver of rats treated with copper albuminate.

scholarly journals Incorporation of ribonucleic acid in vitro into dense ribonucleoprotein-like materials by isolated rat liver nuclei

1978 ◽  
Vol 174 (2) ◽  
pp. 503-508 ◽  
Author(s):  
I Suzuka
Keyword(s):  
Rat Liver ◽  
Ribonucleic Acid ◽  
Free System ◽  
Isolated Rat Liver ◽  
Cell Free System ◽  
Rat Liver Nuclei ◽  
A Cell ◽  
Liver Nuclei ◽  
Isolated Rat

A cell-free system of isolated rat liver nuclei is described which permits an active incorporation of newly synthesized RNA into ‘dense’ ribonucleoprotein-like materials. The reaction is stimulated with increasing amounts of cytosol protein isolated from rat liver. This indicates that cytosol protein plays an important role in the formation of such material.

scholarly journals Experimental conditions affecting ribonucleic acid polymerase in isolated rat liver nuclei. Effect of nucleoside triphosphate concentration, temperature, ammonium sulphate and heparin

1969 ◽  
Vol 112 (5) ◽  
pp. 721-727 ◽  
Author(s):  
F. Novello ◽  
F. Stirpe
Keyword(s):  
Ionic Strength ◽  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
High Ionic Strength ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Low Ionic Strength ◽  
Isolated Rat

1. The conditions affecting the activity of RNA polymerase in isolated rat liver nuclei were studied with Mg2+ or Mn2+ as activating ions. 2. The enzyme assayed with Mg2+ and at low ionic strength is saturated by a lower concentration of nucleotide substrates than if assayed with Mn2+ at low ionic strength or with either ion at high ionic strength. 3. At low and at high ionic strength the incorporation of AMP is affected in a similar way by variations in the temperature of incubation. Preincubation at 37° impairs the AMP incorporation. 4. Heparin stimulates the RNA polymerase activity in the presence of Mn2+. 5. Both ammonium sulphate and heparin ‘restart’ the reaction if added after 15min., the effect being more marked with ammonium sulphate than with heparin, and also more marked in the presence of Mn2+ than of Mg2+. 6. α-Amanitin abolishes the effect of ammonium sulphate and of heparin.

scholarly journals Decreased ribonucleic acid synthesis in isolated rat liver nuclei during starvation

1970 ◽  
Vol 120 (2) ◽  
pp. 381-384 ◽  
Author(s):  
D. Rickwood ◽  
H. G. Klemperer
Keyword(s):  
Rna Polymerase ◽  
Ammonium Sulphate ◽  
Ribonucleic Acid ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Acid Synthesis ◽  
Isolated Nuclei ◽  
Isolated Rat Liver ◽  
Liver Nuclei ◽  
Isolated Rat

1. Isolated nuclei from starved rats showed a lowered incorporation of [14C]UMP into RNA. 2. The Mg2+-dependent incorporation was decreased by 30% after 1 day of starvation, but incorporation in the presence of Mn2+ and ammonium sulphate decreased only after longer periods of starvation. 3. RNA synthesis by nuclei in the presence of excess of added RNA polymerase was unchanged after 1 day of starvation and was inhibited by 20% after 4 days. 4. The capacity of nuclei to bind actinomycin D was unchanged after 1 day and was decreased by 20% after 4 days of starvation.

Sign in / Sign up

Export Citation Format

Share Document