Effect of aflatoxins on ATPase activity of rat liver mitochondria

1975 ◽  
Vol 13 (5) ◽  
pp. 638-640 ◽  
Author(s):  
M. Ramachandra Pai ◽  
N. Jayanthi Bai ◽  
T. A. Venkitasubramanian
Keyword(s):  
Atpase Activity ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria

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.

scholarly journals The ultrastructure and ATPase nature of polar membrane in Campylobacter jejuni

1988 ◽  
Vol 34 (5) ◽  
pp. 594-604 ◽  
Author(s):  
F. M. Brock ◽  
R. G. E. Murray
Keyword(s):  
Atpase Activity ◽  
Campylobacter Jejuni ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Cell Extract ◽  
Histochemical Staining ◽  
Soluble Form ◽  
Rat Liver Mitochondria ◽  
Whole Cell ◽  
Whole Cell Extract

Polar membrane in Campylobacter jejuni has been visualized on membrane vesicles. It was composed of doughnut-shaped particles 5–6 nm in diameter, with stalks, arranged in a hexagonal array. This structure was stabilized on the membrane by a high ionic strength buffer in the presence of 2-mercaptoethanol. Histochemical staining indicated localized ATPase activity at the poles of the cells. An ATPase with distinctive properties has been isolated and purified from this organism; it gives a specific activity of approximately 0.3 units/mg of protein. Electron microscopy showed doughnut-shaped particles 5–6 nm in diameter. Nondissociating and sodium dodecyl sulfate – polyacrylamide gel electrophoresis of the purified enzyme revealed, respectively, a single band with ATPase activity and a molecular weight of ca. 75 – 000 Da. The enzyme was cold labile and activity was abolished by trypsin. Dicylohexylcarbodiimide inhibited the membranebound form of the enzyme, but did not inhibit the soluble form. Oligomycin had no inhibitory activity on either form of the enzyme. The enzyme specifically hydrolysed ATP, but other nucleotide substrates were not degraded. The enzyme was activated by Mg2+ and inhibited by Ca2+, whereas other ions had no effect on activity. Antibodies prepared to this enzyme bound to the polar regions of whole cells as shown by protein A – colloidal gold immunoelectron microscopy. The antibodies to this ATPase cross reacted (shown by Western blotting) with four proteins from a whole-cell extract of this organism, two proteins in Aquaspirillum serpens MW5, and three proteins from Escherichia coli K12. They did not cross-react with any proteins from Spirillum volutans, Methanococcus voltae, Vibrio cholerae, or rat liver mitochondria. Antibodies raised against the F1-ATPase of E. coli K12 cross reacted with six proteins in a whole-cell extract of this organism, and one protein species in each of the whole-cell extracts of V. cholera, A. serpens MW5, S. volutans, and rat liver mitochondria. These antibodies did not recognize any whole cell proteins from either C. jejuni or M. voltae. These results along with the ATPase activity localized by histochemical staining suggest that polar membrane is an assembly of ATPase molecules at the poles of the cell and that the ATPase isolated from C. jejuni is serologically and structurally unusual.

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