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At least 1,621 records · Page 90Linked to original sources
PubMed1984

Monoclonal antibodies to mitochondrial F1-ATPase and oligomycin sensitivity conferring protein (OSCP). Tools for recognition of well conserved and essential antigenic sites.

The preparation of anti-OSCP monoclonal antibodies is described for the first time. One of these antibodies prevents the activating effect of OSCP in reconstitution experiments. These antibodies and antibodies previously obtained against the alpha- and beta-subunits of pig heart mitochondrial F1-ATPase have been used to look for well conserved epitopes in various species. One anti-beta antibody can recognize all species tested while the anti-OSCP antibodies only recognize the pig or beef enzyme. The above anti-beta antibody inhibits ATP synthesis without modifying the rate of ATP hydrolysis. This antibody also prevents the ADP-induced hysteretic inhibition of F1-ATPase.

Adenosine Triphosphatases↗
PubMed1984

Calmodulin binding proteins in rat liver mitochondria.

Calmodulin binding proteins have been found in submitochondrial fractions obtained from highly purified rat liver mitochondria. The matrix fraction contains two major calmodulin binding proteins: one, having Mr of 145,000, apparently is carbamoyl-phosphate synthetase. Another has a Mr of 58,000 and has not been associated with enzyme activities. A major calmodulin binding protein of unknown function and having Mr of 32,000 has been found in the Triton X-100 solubilizate of the inner membrane. Minor amounts of two calmodulin binding proteins having Mr of about 37,000 and 56,000 have been found in the outer membrane.

Animals↗
PubMed1987

Anti-lipoperoxidation action of food restriction.

Chronic food restriction inhibited the age-related increase of malondialdehyde production and lipid hydroperoxides in liver mitochondrial and microsomal membranes of ad libitum fed Fischer 344 rats. The anti-lipoperoxidation action of food restriction could not be attributable to the changes in membrane lipid content nor vitamin E status. Restricting calories modified membrane fatty acid composition by increasing linoleic acid and decreasing docosapentaenoic acid content in both membranes. The significance of the fatty acid modification was discussed in terms of anti-lipoperoxidation and membrane fluidity.

Aging↗
PubMed1989

Lucigenin chemiluminescence and its relationship to mitochondrial respiration in phagocytic cells.

Unstimulated alveolar macrophages, but not polymorphonuclear leukocytes, elicit chemiluminescence from lucigenin which cannot be entirely accounted for by the resting level of superoxide generation. This chemiluminescence was inhibited by both superoxide scavengers and inhibitors of mitochondrial respiration. Although 12-O-tetradecanoyl phorbol-13-acetate addition resulted in a significant increase in cellular superoxide generation, an unexpected decrease in lucigenin chemiluminescence was noted. These results suggest that mitochondria in alveolar macrophages may be a site of lucigenin accumulation and dioxygenation and that 12-O-tetradecanoyl phorbol-13-acetate may modulate this activity.

Acridines↗
PubMed1989

Selective inhibition of complex I of the brain electron transport system by tetrahydroisoquinoline.

The effects of 1,2,3,4-tetrahydroisoquinoline on the enzyme-protein complexes in the electron transport system were studied in mitochondria isolated from mouse brains. Tetrahydroisoquinoline significantly inhibited the activity of NADH-ubiquinone reductase, but had no effect on the activities of succinate-ubiquinone reductase, dihydroubiquinone-cytochrome c reductase, or ferrocytochrome c-oxygen reductase. The biochemical properties of tetrahydroisoquinoline in this study were quite similar to those of the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium ion.

Animals↗
PubMed1989

Orientation of chargerin II (A6L) in the ATP synthase of rat liver mitochondria determined with antibodies against peptides of the protein.

Previous studies suggested that the hydrophobic protein chargerin II, which is encoded in the unidentified reading frame A6L of mitochondrial DNA (URFA6L), may have a key role in the energy transduction by mitochondrial ATP synthase because an antibody against chargerin II inhibited ATP synthesis and ATP-Pi exchange, in an energy-dependent fashion. In the present work, the orientation of chargerin II in Fo of the ATP synthase of rat liver mitochondria was examined using antibodies against peptides of chargerin II. Results showed that its N-terminal region (about 8 amino acid residues) was exposed on the surface of the C-side of Fo, but its C-terminal and charge-cluster regions were buried in Fo.

Animals↗
PubMed1989

Characterization of the submitochondrial compartments: study of the site of synthesis of dolichol and dolichol-linked sugars.

The fractionation of mitochondrial membranes on discontinuous sucrose gradient leads to the obtaining of free outer membranes, free inner membranes and two distinct membrane contact site populations characterized as follows. Only outer membrane contact sites and inner membrane contact sites bind hexokinase. Outer membranes and outer membrane contact sites are cholesterol-rich fractions. The endogenous dolichol content is twice fold higher in outer membranes and outer membrane contact sites than in inner membranes and inner membrane contact sites, only the biosynthesis of dolichol in inner membrane contact sites is not stimulated by addition of exogenous [14C]-IPP and FPP. The glycosylation of endogenous dolichol from labeled nucleotide-sugars (UDP-GlcNAc, GDP-Man and UDP-Glc) leads to the synthesis of dolichol-pyrophosphoryl-sugars and dolichol-monophosphoryl-sugars with the rate of synthesis proportional to the dolichol content of each submitochondrial fraction.

Animals↗
PubMed1989

Mitochondria and microsomal membranes have a free radical reductase activity that prevents chromanoxyl radical accumulation.

Enzyme-dependent mechanisms which prevent accumulation of chromanoxyl radicals derived from the vitamin E analogue, 2,2,5,7,8-pentamethyl-6-hydroxycromane (PMC), were characterized in rat liver microsomal and mitochondrial membranes. The free radical oxidation product of PMC (chromanoxyl radical) was generated in membranes using either photochemical (uv light) or enzymatic (lipoxygenase and arachidonic acid) methods and detected by ESR. Substrates (NADH or NADPH) prevented accumulation of chromanoxyl radicals until the substrate was fully consumed. In microsomes, reduced glutathione increased the efficacy of NADPH in preventing the accumulation of the chromanoxyl radical, but was without effect in the absence of NADPH. Ascorbate also prevented accumulation of the chromanoxyl radical. It is concluded that rat liver microsomes and mitochondria have both enzymatic and non-enzymatic mechanisms for reducing chromanoxyl radicals.

Animals↗
PubMed1989

Modulation of mitochondrial F0F1 catalysis by boundary and bulk phase phospholipids.

The importance of boundary and bulk phase phospholipids was studied on a mitochondrial ATPase complex isolated by AH-Sepharose chromatography as described by Dreyfus et al (1984, Anal. Biochem. 142,215-220), this preparation was devoid of the adenine nucleotide carrier. The presence of isoelectric or acidic phospholipids during the purification in the column allows the exchange of tightly bound phospholipids up to 95%. ATP hydrolysis and oligomycin sensitivity were slightly affected by the nature of boundary and bulk phase phospholipids, while Pi-ATP exchange was highly inhibited.

Adenosine Triphosphate↗
PubMed1990

The triterpene celastrol as a very potent inhibitor of lipid peroxidation in mitochondria.

The inhibitory effect of the dienone-phenolic triterpene, celastrol, on lipid peroxidation in rat liver mitochondrial membranes induced by ADP and Fe2+ was studied. The anti-peroxidative effect of celastrol was very strong: its 50% inhibitory concentration was 7 microM, and it was about 15 times more effective than alpha-tocopherol. Celastrol scavenged 1.5 molar equivalents of radicals in homogeneous aqueous ethanolic solution, whereas cysteine and alpha-tocopherol scavenged one and two molar equivalents of radicals, respectively. The process of anti-peroxidation of celastrol was biphasic, possibly due to stepwise inhibitions of peroxidation in the outer and inner mitochondrial membranes.

Animals↗