Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Submitochondrial Particles”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,513 records · Page 84Linked to original sources
PubMed1980

Effects of pargyline and diethyldithiocarbamate in vivo treatment on aldehyde dehydrogenase activities of submitochondrial fractions.

1) Aldehyde dehydrogenase with a Km for acetaldehyde in the micromolar range (referred to as low Km-AldDH) is located in the matrix and that with a Km in the millimolar range (referred to as high Km-AldDH) is located in both the matrix and the outer membrane of mitochondria. 2) Pargyline in vivo treatment (100 mg/kg i.p.) caused a complete inhibition of the low Km-AldDH activity of the matrix fraction but caused only a 10% inhibition of the high Km-AldDH activities of the matrix and the outer membrane fractions. Diethyldithiocarbamate (DDC) treatment (700 mg/kg i.p.) caused less than 80% inhibition of the low Km-AldDH activity of the matrix fraction and caused a 20% inhibition of the high Km-AldDH activity of the matrix fraction. DDC treatment had no effect on the enzyme activity of the outer membrane fraction. The difference in the degree of inhibition of the low Km-AldDH activity of the matrix fraction by pargyline and DDC treatment may cause different blood acetaldehyde levels during ethanol oxidation.

Acetaldehyde↗
PubMed1981

Electron microscopy of cytodifferentiation and its subcellular steroidogenic sites in the theca cell of the human ovary.

The cytodifferentiation and subcellular steroidogenic sites in the theca cell of the human ovary during the follicular phase were investigated using the electron microscopic cytochemistry. Only fibroblast-like cells were seen around or near the primordial follicle. In the theca interna of the secondary and Graafian follicle however there were three different cell types: fibroblast-like cells, theca gland cells (steroid-secreting cells) and transitional cells (partially or incompletely differentiated theca cells). On the other hand the theca externa of these follicles consisted mainly of fibroblast-like cells. The hallmarks of the cytodifferentiation of the theca cell were: 1) the appearance of lipid droplets, 2) a structural change of the mitochondrial cristae from lamellar to tubular form and 3) the appearance and development of smooth endoplasmic reticulum. Reaction products of 3 beta-hydroxysteroid ferricyanide reductase, indicating 3 beta-hydroxysteroid dehydrogenase activity, were localized on tubular or lamellar cristae and inner membrane of the mitochondria, and on the membranes of smooth endoplasmic reticulum in the transitional cell as well as in the theca gland cell of the secondary and Graafian follicle. From these data, it is suggested that the transitional cell has a steroid-secreting activity and also plays an important role in follicular development in human reproduction.

3-Hydroxysteroid Dehydrogenases↗
PubMed1989

Synthesis of phosphatidylcholine and phosphatidylglycerol in rat lung mitochondria.

The mitochondrial fraction of adult rat lung contains choline phosphotransferase (EC 2.7.8.2) activity which can not be explained by microsomal contamination estimated on the basis of marker enzyme distribution. Mitochondrial (14C)glycerol-3-phosphate incorporation into PC (phosphatidylcholine) can be distinguished from the microsomal incorporation by different sensitivity to N-ethylmaleimide inhibition. The data indicate that rat lung mitochondria have the intrinsic capability to synthesize PC. Both synthesis of PC and PG (phosphatidylglycerol) are susceptible to isotonic tryptic attack against the cytoplasmic face of isolated rat lung mitochondria, suggesting the outer membrane location of crucial activities involved in the formation of these phospholipids. Rat liver mitochondria are different from rat lung mitochondria with respect to their capability to synthesize PC, their rate of (14C)glycerol-3-phosphate incorporation into PG as well as the submitochondrial site of PG formation.

Animals↗
PubMed1979

Isolation of intramitochondrial bodies in bovine adrenocortical cells by density gradient centrifugation.

Two method for isolating the intramitochondrial bodies from bovine adrenocortical cells are proposed. Electron microscopic examination shows that discontinuous sucrose density gradient centrifugation can separate the fraction rich in intramitochondrial bodies, but some indistinguishable fragments remain among them. Continuous sucrose density gradient centrifugation is probably superior to the former method in obtaining a highly purified fraction of the bodies. The amido black positive granules, presumed to be intramitochondrial bodies, are collected in the fractions of the sucrose density of around 1.27 (1.23--1.30), which lack cytochrome c oxidase activity.

Adrenal Cortex↗
PubMed1979

Lipid protein interactions in mitochondria. VIII. Effect of general anesthetics on the mobility of spin labels in lipid vesicles and mitochondrial membranes.

We have studied the effect of general anesthetics on the mobility of two stearic acid spin labels (5-doxyl stearic acid and 16-doxyl stearic acid) in bovine heart mitochondria and in phospholipid vesicles made from either mitochondrial lipids or commercial soybean phospholipids. The general anesthetics used include nonpolar compounds (alcohols, halothane, pentane, diethyl ether, chloroform) and the amphiphatic compound, ketamine. All anesthetics tested increase the mobility of the spin labels in phospholipid vesicles to a limited extent up to a concentration where the ESR spectra become those of free spin labels. On the other hand, anesthetics have a pronounced effect on mitochondrial membranes at concentrations as low as those known to produce general anesthesia; the effect is lower near the bilayer surface (5-doxyl stearic acid) and very strong in the bilayer core (16-doxyl stearic acid). The effects of anesthetics are mimicked by the detergent, Triton X-100. We suggest that the discrepancy between the action of anesthetics in mobilizing the spin labels in lipid vesicles and in membranes results from labilization of lipid protein interactions.

Anesthetics↗
PubMed1981

Antimitochondrial antibodies (AMA) in primary biliary cirrhosis. I. Separation of the PBC antigen activity from mitochondrial ATPase activity.

Antimitochondrial antibodies are found in a variety of autoimmune liver diseases, particularly primary biliary cirrhosis. The antigen against which these antibodies are directed is localized on the inner mitochondrial membrane. Earlier work suggested that this antigen was associated with the mitochondrial ATPase. However, we have succeeded in separating the enzyme activity from the antigenic activity using gel filtration and ion-exchange chromatography. Furthermore, the antigenic activity is not affected by modulators of ATPase enzymatic activity like aurovertin or oligomycin. The antigenic activity is, however, very susceptible to reagents which block thiol groups. The mitochondrial antigen, in contrast to the ATPase enzyme, is found in high amounts in brown fat mitochondria. Identification of this antigen may help to explain why specific antimitochondrial antibodies arise in the sera of patients with primary biliary cirrhosis.

Adenosine Triphosphatases↗
PubMed1981

Isolation, characterization, and reconstitution of a solubilized fraction containing the hydrophobic sector of the mitochondrial proton pump.

The hydrophobic sector of the mitochondrial ATPase complex was purified by sequential extraction with cholate and octylglucoside, by further differential solubilization with guanidine and cholate in the presence of phosphatidylcholine, and by fractionation with ammonium sulfate. A polypeptide with a mass of 28,000 dalton was present in the purified hydrophobic section which was cleaved by trypsin, resulting in loss of reconstitution activity. In contrast, dicyclohexylcarbodiimide-binding proteolipid remained unimpaired after exposure to trypsin. The 32Pi-ATP exchange activity of the reconstituted ATPase complex was inhibited by p-hydroxymercuribenzoate, which reacted primarily with the 28,000-dalton protein, as monitored by acrylamide gel electrophoresis with 14C-labeled inhibitor. The function of a 22,000-dalton polypeptide and of some minor components in the region of the proteolipid remains unknown. An examination of the phospholipid requirements for reconstitution of an active complex revealed an unexpected discrepancy. With an excess of phosphatidylethanolamine, optimal reconstitution of 32Pi-ATP exchange and ATP synthesis in the presence of bacteriorhodopsin and light was achieved: at a high phosphatidylcholine:phosphatidylethanolamine ratio, the rate of ATP synthesis remained high, but the rate of 32Pi-ATP exchange dropped precipitously. A new procedure is described for the reconstitution of the ATPase complex with purified phospholipids which is stable for at least 15 days.

Adenosine Triphosphatases↗
PubMed1978

Oxidation-reduction midpoint potentials of mitochondrial flavoproteins and their intramitochondrial localization.

Spectrophotometric and fluorimetric substrate couple titrations and potentiometric spectrophotometric titrations were used to determine the oxidation-reduction potentials of components showing absorbance or fluorescence at the wavelengths attributable to the flavoproteins of mitochondria fractionated using digitonin together with sonication. A pure mitoplast fraction devoid of cytochrome b5 contamination could be obtained using 230 micrograms digitonin/mg of mitochondrial protein. The digitonin-soluble fraction contained a species having Em7.4 = -123 mV and probably represents the outer membrane flavoproteins. The inner membrane-matrix fraction, treated with ultrasound, provided evidence of a flavoprotein species with redox potential (Em7.4 = -302 mV) in the matrix fraction. The -302 mV component is probably lipoamide dehydrogenase. A high redox potential species with Em7.4 = +19 mV in titrations with the succinate fumarate couple was located in the inner membrane vesicles and is probably identical with succinate dehydrogenase. The electron-transferring flavoprotein (ETF) was isolated from bovine heart mitochondria and its Em7.4 = -74 mV determined. The component in the matrix fraction with an apparent Em7.4 = -56 mV probably represents ETF, and that in the inner membrane fraction with an apparent Em7.4 = -43 mV the NADH dehydrogenase flavoprotein. A component in an apparently low concentration with Em7.4 = +30 mV was detected in the inner membrane fraction. This probably represents the ETF-dehydrogenase flavoprotein. The origin of the flavoprotein fluorescence of mitochondria and intact tissues is discussed.

Animals↗
PubMed1986

Is there sufficient experimental evidence to consider the mitochondrial cytochrome bc1 complex a proton pump? Probably no.

The electron flow through the cytochrome bc1 complex of the mitochondrial respiratory chain is accompanied by vectorial proton translocation, though the mechanism of the latter phenomenon has not yet been clarified. Several proposed hypotheses are briefly presented and discussed here. Recently, a number of papers have appeared claiming the existence of a proton pump in the enzyme mainly on the basis of the interaction of the complex with N,N'-dicyclohexylcarbodiimide. These data are reviewed here with the aim of showing their ability to fit multiple interpretations. This together with some other arguments leads to the conclusion that a proton pump in the mitochondrial bc1 complex has not yet been demonstrated.

Animals↗
PubMed1982

Mitochondrial chemiluminescence elicited by acetaldehyde.

Acetaldehyde-dependent chemiluminescence has been found to be a sensitive technique for the study of superoxide and hydrogen peroxide formation in beef heart mitochondria. The system responds to ATP and antimycin A with increased emission intensities and to ADP and rotenone with decreased intensities, indicating that the chemiluminescence reflects the energy status of the mitochondrion. These effects are based on the ability of acetaldehyde to react with superoxide and hydrogen peroxide to form metastable intermediates which decay spontaneously with the emission of light. Additionally, these intermediates can react with cyanide to give alternative products which can also decay with the emission of light, the cyanide-evokable chemiluminescence. The interaction of acetaldehyde with mitochondria is complex because acetaldehyde can serve as a hydrogen source for NADH and as an inhibitor (at high concentration) of electron transport, and appears to be a reducing agent for a heat-stable site that autoxidatively generates HOOH from O2-.. Inasmuch as acetaldehyde is a metabolite of ethanol, this broad spectrum of reactivity may play a role in the hepatic and cardiac toxicity that is associated with alcoholism. The heat-stable site that generates HOOH from O2-. has been studied further and appears to contain vicinal dithiol which is primarily responsible for the cyanide-evokable chemiluminescence.

Acetaldehyde↗
PubMed1987

On the mechanism of the reconstitution of F1-depleted ATPase complex with purified F1: possible conformational effects.

The membrane sector (F0) of H+-ATPase was prepared by trypsin and urea treatment of F1-F0 and reconstituted with purified F1. The oligomycin sensitivity of the reconstituted F1-F0 complex obtained by treating F1 or F0 with Mg2+ before binding is much higher than that obtained without Mg2+ treatment. The greater change in the intrinsic fluorescence of the reconstituted F1-F0 complex obtained by Mg2+ treatment suggests that conformational changes may occur during the reconstitution. We deduce that Mg2+ binds to membrane lipids, thus decreasing membrane fluidity and changing the physical state of the lipids to provide a suitable microenvironment for conformational changes in F0. The data also suggest that the conformational change in the F0 portion of the F1-F0 complex can be transmitted to the F1 portion, the conformation of which is in turn altered, resulting in the formation of an F1-F0 complex with high oligomycin sensitivity. On the other hand, Mg2+ may act on F1 directly to induce a suitable conformational change which is then transmitted to F0, resulting in the formation of an H+-ATPase with greater sensitivity to oligomycin.

Animals↗
PubMed1981

Structure of F1-ATPase.

F1-ATPases are large multimeric proteins that can be isolated from the membrane bound system that catalyzes the phosphorylation of ADP by inorganic phosphate in bacteria, plants, and mitochondria. They can be visualized in electron micrographs of the inner mitochondrial membranes where they appear as large protruding spheres 90 A in diameter. The purified F1-ATPases have a molecular weight of 320,000 to 400,000 daltons and are composed of five non-identical subunits (alpha, beta, gamma, delta and epsilon). The stoichiometry of these subunits in the complex is still unknown but compositions of the type alpha3beta3gamma delta epsilon and alpha2beta2gamma2delta2epsilon2 were found to be consistent with some of the available experimental data. This review discusses the recent data and the experimental approaches utilized for the structural characterization of F1-ATPases.

Adenosine Triphosphatases↗
PubMed1993

Inhibition of membrane-bound succinate dehydrogenase by fluorescamine.

Fluorescamine rapidly inactivated membrane-bound succinate dehydrogenase. The inhibition of the enzyme by this reagent was prevented by succinate and malonate, suggesting that the group modified by fluorescamine was located at the active site. The modification of the active site sulfhydryl group by 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) did not alter the inhibitory action of fluorescamine. However, the protective effect of malonate against fluorescamine inhibition was abolished in the enzyme modified at the thiol.

Animals↗
PubMed1990

On the nature of the uncoupling effect of fatty acids.

The effect of palmitic acid on the electrical potential differences delta psi across the inner mitochondrial membrane appears to depend on the medium in which mitochondria are incubated. In medium A (cf. Luvisetto et al. (1987), Biochemistry, 26, 7332-7338) delta psi decreases much more than in medium B (cf. Rottenberg and Hashimoto (1986), Biochemistry, 25, 1747-1755) at concentrations of fatty acid which equally stimulate the rate of respiration in state 4. Valinomycin and NaCl were both present in medium B and absent in medium A. However, in both media the pattern of the P/O ratio as a function of antimycin in the presence of a constant amount of palmitic acid or of FCCP shows similar behaviour. We conclude that in both media palmitic acid increases the membrane conductance to protons, but for unclear reasons the delta psi assay fails to measure the decline of delta psi in medium B. However, the increase in membrane conductance induced by palmitic acid does not quantitatively account for the stimulation of the rate of respiration.

Adenosine Triphosphate↗
PubMed1990

The use of amphipathic maleimides to study membrane-associated proteins.

A series of amphiphilic polymethlyenecarboxymaleimides has been synthesized for use as sulfhydryl reagents applicable to membrane proteins. Physical properties of the compounds which are relevant to their proposed mode of action have been determined. By comparing rates of reaction in aqueous and aprotic solvents, the compounds have been shown to react exclusively with the thiolate ion. The effects of the reagents on three membrane-associated proteins are reported, and in two cases a comparative study has been made of the effects on the proteins in the absence of membranes. A mechanism is proposed whereby the reagents are anchored at the lipid/water interface by the negatively charged carboxyl group, thus sitting the reactive maleimide in a plane whose depth is defined by the length of the reagent. Supporting evidence for this model is provided by the inability of the reagents to traverse membranes, and variation of their inhibitory potency with chain length when the proteins are embedded in the membrane, but not when extracted into solution. As examples of general use of the reagents to probe sulfhydryl groups in membrane proteins, the reagents have been used to (a) determine the depths in the membrane at which two populations of sulfhydryl groups occur in the mitochondrial phosphate transporter; (b) locate a single sulfhydryl associated with the active site of D-beta-hydroxybutyrate dehydrogenase in the inner mitochondrial membrane; (c) examine sulfhydryl groups in the D-3-glyceraldehyde phosphate dehydrogenase associated with the human red blood cell membrane.

Animals↗
PubMed1987

Specific polypeptide differences in normal versus malignant human breast tissues by two-dimensional electrophoresis.

Postmitochondrial and cytosolic polypeptides were extracted from human breast tumors and non-malignant breast tissue and analyzed using high resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Approximately 800-1000 postmitochondrial and 600-800 silver stained cytosolic polypeptides were detected over the pH range of 4.8 to 7.5 and molecular weight range of 18-120 kDa. The 2D-PAGE patterns of polypeptides from normal and malignant tissue were very similar, although both qualitative and quantitative polypeptide differences were noted. Six cytosolic polypeptides (pI/molecular weight X 10(-3) 5.20/80 kDa, 5.75/43, 6.25/40, 5.43/35, 5.45/34.5, 5.50/34 and 6.15/24 were expressed only in malignant tissues. One constitutive polypeptide, 7.25/52, was not detected in any of the malignant tissue samples. Quantitatively, marked differences in spot density were noted in polypeptides localized mainly in the molecular weight ranges of 22-40 kDa and pI ranges of 5.65-7.00. A general increase in polypeptide expression was noted in malignant tissues as compared to normal. Twenty-two polypeptides were significantly and consistently increased in tumor samples while only one polypeptide was decreased. One polypeptide, p24 (6.15/24) was expressed in greatest concentrations in tumors which also expressed the greatest estrogen receptor content. Expression of p24 was markedly reduced in normal tissue and malignant tissues expressing low levels of estrogen and progesterone receptors.

Biomarkers, Tumor↗
PubMed1987

Purification and characterization of the voltage-dependent anion channel from the outer mitochondrial membrane of yeast.

The outer mitochondrial membranes of all organisms so far examined contain a protein which forms voltage-dependent anion selective channels (VDAC) when incorporated into planar phospholipid membranes. Previous reports have suggested that the yeast (Saccharomyces cerevisiae) outer mitochondrial membrane component responsible for channel formation is a protein of 29,000 daltons which is also the major component of this membrane. In this report, we describe the purification of this 29,000-dalton protein to virtual homogeneity from yeast outer mitochondrial membranes. The purified protein readily incorporates into planar phospholipid membranes to produce ionic channels. Electrophysiological characterization of these channels has demonstrated they have a size, selectivity and voltage dependence similar to VDAC from other organisms. Biochemically, the purified protein has been characterized by determining its amino acid composition and isoelectric point (pI). In addition, we have shown that the purified protein, when reconstituted into liposomes, can bind hexokinase in a glucose-6-phosphate dependent manner, as has been shown for VDAC purified from other sources. Since physiological characterization suggests that the functional parameters of this protein have been conserved, antibodies specific to yeast VDAC have been used to assess antigenic conservation among mitochondrial proteins from a wide number of species. These experiments have shown that yeast VDAC antibodies will recognize single mitochondrial proteins from Drosophila, Dictyostelium and Neurospora of the appropriate molecular weight to be VDAC from these organisms. No reaction was seen to any mitochondrial protein from rat liver, rainbow trout, Paramecium, or mung bean. In addition, yeast VDAC antibodies will recognize a 50-kDa mol wt protein present in tobacco chloroplasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗