scholarly journals Biochemical heterogeneity of rat liver mitochondria separated by rate zonal centrifugation

1972 ◽  
Vol 129 (1) ◽  
pp. 209-218 ◽  
Author(s):  
M. A. Wilson ◽  
J. Cascarano
Keyword(s):  
Cytochrome C ◽  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Cytochrome B ◽  
Rat Liver ◽  
Nadh Dehydrogenase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Osmotic Gradient ◽  
Glycerophosphate Dehydrogenase

1. Rat liver mitochondria were separated on the basis of their sedimentation coefficients in an iso-osmotic gradient of Ficoll–sucrose by rate zonal centrifugation. The fractions (33, each of 40ml) were collected in order of decreasing density. Fractions were analysed by spectral analysis to determine any differences in the concentrations of the cytochromes and by enzyme analyses to ascertain any differences in the activities of NADH dehydrogenase, succinate dehydrogenase and α-glycerophosphate dehydrogenase. 2. When plotted as% of the highest specific concentration, the contents of cytochrome a+a3 and cytochrome c+c1 were constant in all fractions but cytochrome b was only 65% of its maximal concentration in fraction 7 and increased with subsequent fractions. As a result, the cytochrome b/cytochrome a+a3 ratio almost doubled between fractions 7 and 25 whereas the cytochrome c+c1/cytochrome a+a3 ratio was unchanged. 3. Expression of the dehydrogenase activities as% of highest specific activity showed the following for fractions 6–26: NADH dehydrogenase activity remained fairly constant in all fractions; succinate dehydrogenase activity was 62% in fraction 6 and increased steadily to its maximum in fraction 18 and then decreased; the activity of α-glycerophosphate dehydrogenase was only 53% in fraction 6 and increased slowly to its peak in fractions 22 and 24. 4. These differences did not result from damaged or fragmented mitochondria or from microsomal contamination. 5. These results demonstrate that isolated liver mitochondria are biochemically heterogeneous. The importance of using a system for separating biochemically different mitochondria in studies of mitochondrial biogenesis is discussed.

The inhibition of mammalian mitochondrial NADU oxidation by chloramphenicol and its isomers and analogues

1968 ◽  
Vol 46 (9) ◽  
pp. 1003-1008 ◽  
Author(s):  
K. B. Freeman ◽  
D. Haldar
Keyword(s):  
Cytochrome B ◽  
Respiratory Chain ◽  
Rat Liver ◽  
Nadh Dehydrogenase ◽  
Coenzyme Q ◽  
Liver Mitochondria ◽  
Heart Mitochondria ◽  
Rat Liver Mitochondria ◽  
Beef Heart ◽  
Beef Heart Mitochondria

Chloramphenicol and its isomers and analogues have been found to inhibit the oxidation of NADH, but not that of succinate, by beef heart mitochondria. They must therefore inhibit the NADH dehydrogenase segment of the respiratory chain. Chloramphenicol gave 50% inhibition at a concentration of 1 mM. The methylthio analogue of chloramphenicol inhibited NADH – coenzyme Q6 reductase but not NADH–ferricyanide reductase. Spectrophotometric observations suggest that these inhibitors act between NADH and flavin in coupled rat liver mitochondria and between flavin and cytochrome b in uncoupled beef heart mitochondria.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

scholarly journals Proton translocation by the mitochondrial cytochrome b-c1 complex is inhibited by NN′-dicyclohexylcarbodi-imide

1982 ◽  
Vol 206 (2) ◽  
pp. 419-421 ◽  
Author(s):  
B D Price ◽  
M D Brand
Keyword(s):  
Electron Transport ◽  
Cytochrome Oxidase ◽  
Cytochrome B ◽  
Rat Liver ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Cytochrome ◽  
Low Concentrations ◽  
Mitochondrial Cytochrome B

NN'-Dicyclohexylcarbodi-imide at low concentrations decreases the H+/2e ratio for rat liver mitochondria over the span succinate to oxygen from 5.9 +/- 0.3 (mean +/- S.E.M.) to 4.0 +/- 0.1 and for the cytochrome b-c1 complex from 3.8 +/- 0.2 to 1.9 +/- 0.1, but has little effect on the H+/2e ratio of cytochrome oxidase. The decrease in stoicheiometry is due, not to uncoupling or inhibition of electron transport, but to inhibition of proton translocation. NN'-Dicyclohexylcarbodi-imide thus ‘decouples’ proton translocation in the cytochrome b-c1 complex.

scholarly journals Cholesterol increase in mitochondria: its effect on inner-membrane functions, submitochondrial localization and ultrastructural morphology

1993 ◽  
Vol 289 (3) ◽  
pp. 703-708 ◽  
Author(s):  
S Echegoyen ◽  
E B Oliva ◽  
J Sepulveda ◽  
J C Díaz-Zagoya ◽  
M T Espinosa-García ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Atpase Activity ◽  
Succinate Dehydrogenase ◽  
Outer Membrane ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Membrane ◽  
Ultrastructural Morphology ◽  
Mitochondrial Inner Membrane

The effect of cholesterol incorporation on some functions of the mitochondrial inner membrane and on the morphology of rat liver mitochondria was studied. Basal ATPase and succinate dehydrogenase activities remained unchanged after cholesterol was incorporated into the mitochondria; however, uncoupled ATPase activity was partially inhibited. The presence of several substrates and inhibitors did not change the amount of cholesterol incorporated, which was localized mostly in the outer membrane. Electron-microscope observations revealed the presence of vesicles between the outer and inner membranes; these vesicles increased in number with the amount of cholesterol incorporated. The data suggest that cholesterol induces the formation of vesicles from the outer membrane, and modifies the activity of stimulated ATPase.

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