scholarly journals Osmotic behavior and permeability of osmotically lysed mitochondria.

1976 ◽  
Vol 70 (2) ◽  
pp. 348-357 ◽  
Author(s):  
C L Bowman ◽  
H Tedeschi ◽  
B J DiDomenico ◽  
F D Tung
Keyword(s):  
External Medium ◽  
Volume Ratio ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Virtual Absence ◽  
Isolated Mitochondria ◽  
Cell Biol ◽  
Molecular Components ◽  
Osmotic Behavior

Experiments were carried out with water-treated isolated rat liver mitochondria (mitochondria ghosts) previously studied by Caplan and Greenawalt (Caplan, A.I., and J.W. Greenawalt. 1966. J. Cell Biol. 31:455-472) and Vasington and Greenawalt (Vasington, F., and J. Greenawalt. 1968. J. Cell Biol. 39:661-675). The ghosts have permeability properties and osmotic behavior comparable to those of isolated mitochondria. Although they have lost most of their internal contents, they must have resealed. Four properties were found which have not been previously described in systems derived from biological membranes: (a) an osmotic behavior in the virtual absence of internal components. (b) a self-arranging property in the formation of invaginations corresponding in morphology to the cristae. The results suggest that the assembly of the molecular components of the inner membrane is sufficient to specify the morphology. Hence the surface area to volume ratio of the vesicles may specify the presence or absence of cristae-like folds. (c) an increase in the permeability of the membranes to sucrose in the presence of iso-osmotic concentrations of sucrose. (d) an independence of the light transmitted by suspensions of the vesicles from the refractive index of the external medium. This observations run counter to the general previous experience with either mitochondria or liposomes.

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 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 Factors influencing the activity of ornithine aminotransferase in isolated rat liver mitochondria

1977 ◽  
Vol 162 (1) ◽  
pp. 147-156 ◽  
Author(s):  
J D McGivan ◽  
N M Bradford ◽  
A D Beavis
Keyword(s):  
Mitochondrial Membrane ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Ornithine Aminotransferase ◽  
Aminotransferase Activity ◽  
Exchange System ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Factors Influencing ◽  
Kinetics Of

1. The characteristics of ornithine catabolism by the aminotransferase pathway in isolated mitochondria were determined. 2. Ornithine synthesis from glutamate and glutamate gamma-semialdehyde produced by the oxidation of proline was studied. No ornithine was formed in the absence of rotenone. 3. The mechanism of ornithine transport was reinvestigated, and the existence of an ornithine+/H+ exchange system postulated. 4. The kinetics of ornithine transport, ornithine catabolism in intact mitochondria and ornithine aminotransferase activity in solubilized mitochondria were compared. It is concluded that ornithine aminotransferase activity in liver mitochondria is rate-limited by the transport of ornithine across the mitochondrial membrane, and that this enzyme is involved primarily in ornithine degradation rather than ornithine synthesis.

scholarly journals Effects of glucagon and N6O2′-dibutyryladenosine 3′:5′-cyclic monophosphate on calcium transport in isolated rat liver mitochondria

1978 ◽  
Vol 176 (1) ◽  
pp. 295-304 ◽  
Author(s):  
B P Hughes ◽  
G J Barritt
Keyword(s):  
Retention Time ◽  
Calcium Transport ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Dibutyryl Cyclic Amp ◽  
Oxygen Utilization ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Isolated Liver ◽  
Stimulation Of

1. The administration of glucagon to fed rats by intraperitoneal injection, or the perfusion of livers from fed rats with glucagon by the method of Mortimore [Mortimore (1963) Am.J. Physiol. 204, 699–704] was associated with increases of 15- and 5-fold respectively, in the time for which a given load of exogenous Ca2+ is retained by mitochondria subsequently isolated from the liver. This effect of glucagon was (a) also induced by N6O2′-dibutyryl cyclic AMP, (b) completely blocked by cycloheximide, (c) relatively slow in onset (15–60 min) and (d) associated with a stimulation of about 20% in the rates of ADP-stimulated oxygen utilization and Ca2+ transport measured in the presence of succinate. 2. Perfusion of livers with glucagon resulted in the isolation of mitochandria which showed a 50% increase, no significant change and a 40% increase in the concentrations of endogenous Ca, Mg and Pi respectively, when compared with mitochondria isolated from control perfused livers. 3. The administration of insulin or adrenaline to fed rats induced increases of 10- and 8-fold respectively, in the time for which Ca2+ is retained by isolated liver mitochondria. Perfusion of livers with insulin had no effect on mitochondrial Ca2+ retention time. 4. The perfusion of livers from starved rats with glucagon, or the administration of either glucagon or insulin to starved rats, increased by about 2.5- and 15-fold respectively, the time for which isolated mitochondria retain Ca2+. 5. Mechanisms which may be responsible for the observed alterations in Ca2+-retention time are discussed.

scholarly journals ANGULAR LIGHT-SCATTERING STUDIES ON ISOLATED MITOCHONDRIA

1961 ◽  
Vol 10 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Gerald S. Gotterer ◽  
Thomas E. Thompson ◽  
Albert L. Lehninger
Keyword(s):  
Light Scattering ◽  
Optical Density ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Density Measurements ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Large Particles ◽  
Scattering Measurements ◽  
Increased Sensitivity

Angular light-scattering studies have been carried out on suspensions of isolated rat liver mitochondria. The angular scatter pattern has a large forward component, typical of large particles. Changes in dissymmetry and in the intensity of light scattered at 90° have been correlated with changes in optical density during the course of mitochondrial swelling and contraction. Such changes can be measured at mitochondrial concentrations much below those required for optical density measurements. Changes in mitochondrial geometry caused by factors "leaking" from mitochondria, not detectable by optical density measurements, have been demonstrated by measuring changes in dissymmetry. Angular light-scattering measurements therefore offer the advantages of increased sensitivity and of added indices of changes in mitochondrial conformation.

scholarly journals Effect of l-leucine on the nitrogen metabolism of isolated rat liver mitochondria

1973 ◽  
Vol 134 (1) ◽  
pp. 209-215 ◽  
Author(s):  
J. D. McGivan ◽  
Norah M. Bradford ◽  
M. Crompton ◽  
J. B. Chappell
Keyword(s):  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Mitochondrial Membrane ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Citrulline Synthesis ◽  
Glutamate Synthesis ◽  
Rate Limiting

1. l-Leucine strongly activated intramitochondrial glutamate dehydrogenase in the direction of glutamate synthesis. 2. In the deamination direction, the enzyme was not stimulated by leucine. This was probably due to a rate-limiting transport of glutamate across the mitochondrial membrane. 3. The effect of leucine on the kinetic constants of glutamate dehydrogenase in a mitochondrial sonicate was studied. 4. In isolated mitochondria, leucine did not stimulate the synthesis of citrulline with glutamate as the source of NH3. 5. Leucine very markedly stimulated the synthesis of glutamate from added 2-oxoglutarate+NH4Cl. 6. Under conditions where glutamate and citrulline could be synthesized simultaneously from added NH4Cl, leucine greatly increased glutamate synthesis at the expense of citrulline synthesis. 7. It is suggested that the intramitochondrial leucine concentration may be a factor influencing the nitrogen metabolism of the liver cell.

Biochemistry of Polyglycerophosphatides. The Mechanism of Cardiolipin Biosynthesis in Isolated Mitochondria

1973 ◽  
Vol 51 (3) ◽  
pp. 286-304 ◽  
Author(s):  
N. Z. Stanacev ◽  
J. B. Davidson ◽  
L. Stuhne-Sekalec ◽  
Z. Domazet
Keyword(s):  
Reaction Mechanism ◽  
Liver Mitochondria ◽  
Water Soluble ◽  
Rat Liver Mitochondria ◽  
Labeled Compounds ◽  
Experimental Conditions ◽  
Isolated Rat Liver ◽  
Isolated Mitochondria ◽  
Membrane Bound ◽  
Isolated Rat

The mechanism of cardiolipin biosynthesis in isolated rat liver mitochondria was studied using endogenously formed and exogenously supplied phosphatidylglycerol-2′-3H in the presence and absence of added Mg2+, Mn2+, CDP-DL-dioleate, and CDP-D-diglyceride-2-14C. With endogenously formed and membrane-bound phosphatidylglycerol-2′-3H and in the presence of Mn2+, the incorporation of CDP-D-diglyceride-2-14C into cardiolipin-3H,14C was demonstrated, establishing the participation of both phosphatidylglycerol-2′-3H and CDP-D-diglyceride-2-14C in the formation of cardiolipin-3H,14C. In addition, the release of water-soluble labeled compounds was measured and the efficiency of glycerol-2-3H recovery after the incubation with mitochondria was determined. It was concluded that under the described experimental conditions the formation of cardiolipin in isolated mitochondria takes place according to the reaction mechanism: phosphatidylglycerol + CDP-diglyceride → cardiolipin. Some aspects of these findings are discussed in detail

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.

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