scholarly journals Importance of the osmolarity of the incubation medium on amino acid incorporation into protein by isolated rat liver mitochondria

1969 ◽  
Vol 111 (5) ◽  
pp. 653-663 ◽  
Author(s):  
D. Haldar ◽  
K. B. Freeman
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Inhibitory Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Mitochondrial Ribosomes ◽  
Isolated Mitochondria ◽  
Escherichia Coli B ◽  
Isolated Rat

1. Incorporation of [14C]leucine into protein by isolated rat liver mitochondria was examined by using incubation media similar to those used by Sandell, Löw & Decken (1967) (medium A) and Roodyn, Reis & Work (1961) (medium B). The incorporation process was found to be almost completely inhibited in medium A. 2. By decreasing the amount of sucrose and omitting tris–hydrochloric acid from medium A, incorporation proceeded at a rate higher than that found in medium B. It was found that the inhibitory action of medium A was due to its high osmolarity. 3. Oxidative phosphorylation and RNA synthesis by the isolated mitochondria proceeded at the same rate in media essentially the same as media A and B. 4. There was a partial inhibitory action of medium A on leucine uptake by the mitochondria and also on the formation of leucyl-transfer-RNA. The major block of inhibition by the hyperosmolarity of medium A seemed to be located at a later step of protein synthesis involving mitochondrial ribosomes. 5. Protein synthesis by Escherichia coli B was only slightly inhibited, if at all, in hyperosmotic media in which protein synthesis by isolated mitochondria was completely stopped.

scholarly journals Fluorocitrate inhibition of aconitate hydratase and the tricarboxylate carrier of rat liver mitochondria

1973 ◽  
Vol 134 (1) ◽  
pp. 217-224 ◽  
Author(s):  
M. D. Brand ◽  
Susan M. Evans ◽  
J. Mendes-Mourão ◽  
J. B. Chappell
Keyword(s):  
Rat Liver ◽  
Inhibitory Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Exchange Reactions ◽  
Aconitate Hydratase ◽  
Isolated Rat Liver ◽  
Tricarboxylate Carrier ◽  
Hydratase Activity ◽  
Isolated Rat

1. The effect of biologically synthesized and purified fluorocitrate on the metabolism of tricarboxylate anions by isolated rat liver mitochondria was investigated, in relation to the claim by Eanes et al. (1972) that this fluoro compound inhibits the tricarboxylate carrier at concentrations at which it has little effect on the aconitate hydratase activity. 2. That the inhibitory action of fluorocitrate is at the level of the aconitate hydratase and not at the level of the tricarboxylate carrier is indicated by the following findings. Although the oxidation of citrate and cis-aconitate, but not that of isocitrate, was inhibited by fluorocitrate, the exchange of internal citrate for external citrate or l-malate was not. Had the tricarboxylate carrier been affected, these latter exchange reactions would have been inhibited. 3. By using aconitate hydratase solubilized from mitochondria it was found that with citrate as substrate the inhibition by fluorocitrate was partially competitive (Ki=3.4×10−8m), whereas with cis-aconitate as substrate the inhibition was partially non-competitive (Ki=3.0×10−8m).

scholarly journals Protein-mediated uptake of vitamin B12 by isolated mitochondria

Blood ◽  
1976 ◽  
Vol 47 (6) ◽  
pp. 923-930 ◽  
Author(s):  
RA Gams ◽  
EM Ryel ◽  
F Ostroy
Keyword(s):  
Vitamin B12 ◽  
Rat Liver ◽  
Mitochondrial Respiration ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Isolated Rat

Abstract Protein-mediated B12 uptake by isolated rat liver mitochondria has been shown to be enhanced by plasma transcobalamin (TC-II) but not by salivary R binder in vitro. The process is enhanced by calcium and depends on active mitochondrial respiration. Following uptake, cyanocobalamin is converted to adenosyl and methylcobalamins and released from the mitochondria. TC-II appears to be required for both cellular and mitochondrial uptake of vitamin B12.

scholarly journals Inhibition of protein synthesis by ricin: experiments with rat liver mitochondria and nuclei and with ribosomes from Escherichia coli

1974 ◽  
Vol 142 (3) ◽  
pp. 695-697 ◽  
Author(s):  
Margherita Greco ◽  
Lucio Montanaro ◽  
Francesco Novello ◽  
Cecilia Saccone ◽  
Simonetta Sperti ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Ricinus Communis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Liver Nuclei ◽  
Isolated Rat ◽  
Liver Ribosomes

1. Ricin, a toxic protein from the seeds of Ricinus communis which inhibits poly(U)-directed polyphenylalanine synthesis by rat liver ribosomes (Montanaro et al., 1973), does not affect protein synthesis by isolated rat liver mitochondria. 2. The toxin is ineffective also on poly(U)-directed polyphenylalanine synthesis in reconstituted systems with ribosomes isolated from rat liver mitochondria or from Escherichia coli. 3. Ricin inhibits protein synthesis by isolated rat liver nuclei, but at concentrations much higher than those affecting rat liver ribosomes.

scholarly journals Protein-mediated uptake of vitamin B12 by isolated mitochondria

Blood ◽  
1976 ◽  
Vol 47 (6) ◽  
pp. 923-930
Author(s):  
RA Gams ◽  
EM Ryel ◽  
F Ostroy
Keyword(s):  
Vitamin B12 ◽  
Rat Liver ◽  
Mitochondrial Respiration ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Isolated Rat

Protein-mediated B12 uptake by isolated rat liver mitochondria has been shown to be enhanced by plasma transcobalamin (TC-II) but not by salivary R binder in vitro. The process is enhanced by calcium and depends on active mitochondrial respiration. Following uptake, cyanocobalamin is converted to adenosyl and methylcobalamins and released from the mitochondria. TC-II appears to be required for both cellular and mitochondrial uptake of vitamin B12.

scholarly journals Effect of Polyuridylic and Polyadenylic Acids on Protein Synthesis in Isolated Rat Liver Mitochondria.

1968 ◽  
Vol 22 ◽  
pp. 3072-3080 ◽  
Author(s):  
O. Hänninen ◽  
K. Alanen-Irjala ◽  
Gunilla Carlsson ◽  
Olav Smidsrød
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Rat
Sign in / Sign up

Export Citation Format

Share Document