Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

relationship between levels of cAMP and catabolite repression in yeasts has been investigated. Strains of Saccharomyces cerevisiae, Schizosaccharomyces pombe and Kluyveromyces fragilis were used. The yeasts were grown on different carbon sources to attain various degrees of repression. Galactose repressed as much as glucose, while maltose was less effective. Full derepression was achieved with ethanol. The enzymes tested were fructose-bisphosphatase, malate dehydrogenase, glutamate dehydrogenase (NAD dependent), cytochrome oxidase and isocitrate lyase (this last enzyme was found to be absent in Schizosaccharomyces). The levels of cAMP were 2-3 times higher in the repressed conditions than in the derepressed ones. It is therefore concluded that in yeasts catabolite repression is not mediated by a lowering of the intracellular concentration of cAMP.
 ...
PMID:Catabolite repression in yeasts is not associated with low levels of cAMP. 632 8

Cells of the E3-24 mutant of the strain D273-10B of Saccharomyces cerevisiae, grown in a fermentable substrate not showing catabolite repression of respiration (2% galactose), are able to respire, in spite of their ubiquinone deficiency in mitochondrial membranes. Mitochondria isolated from these mutant cells oxidize exogenous NADH through a pathway insensitive to antimycin A but inhibited by cyanide. Addition of methanolic solutions of ubiquinone homologs stimulates the oxidation rate and restores antimycin A sensitivity in both isolated mitochondria and whole cells. Mersalyl preincubation of isolated mitochondria inhibits both NADH oxidation and NADH-cytochrome c oxido-reductase activity (assayed in the presence of cyanide) with the same pattern. Electrons resulting from the oxidation of exogenous NADH reduce both cytochrome b5 and endogenous cytochrome c. The increase in ionic strength stimulates NADH oxidation, which is also coupled to the ATP synthesis with an ATP/O ratio similar to that obtained with ascorbate plus N,N,N',N'-tetramethyl-p-phenylendiamine (TMPD) as substrate. The effect of cyanide on these activities and on NADH-induced endogenous cytochrome c reduction is also comparable. These results support the existence in vivo and in isolated mitochondria of a energy-conserving pathway for the oxidation of cytoplasmatic NADH not related to the dehydrogenases of the inner membrane, the ubiquinone, and the b-c1 complex, but involving a cytochrome c shuttle between the NADH-cytochrome c reductase of the outer membrane and cytochrome oxidase in the inner membrane.
 ...
PMID:The oxidation of external NADH by an intermembrane electron transfer in mitochondria from the ubiquinone-deficient mutant E3-24 of Saccharomyces cerevisiae. 637 98

Even 70 years ago Gram-negative coccobacilli had been recognized in vaginal discharge and were cultured 30 years ago. The need to have blood in agar medium for cultivation suggested that the organisms might be a Haemophilus species. Later, however, growth characteristics and other features resulted in their being placed in the genus Corynebacterium, before it was realized that this was inappropriate and they were transferred to a new genus and species Gardnerella vaginalis. The organisms are Gram-variable, non-sporing, non-flagellate, non-motile coccobacilli of average size 0.4 X 1-1.5 microns. The cell wall is laminated and some strains possess pili. G. vaginalis is fermentative and dextrose, fructose, galactose, glucose, maltose, mannose, ribose and starch are most likely to be metabolized. However, published patterns of the sugars fermented vary widely and most workers do not rely on such tests as a means of identification. Of many other features exhibited by G. vaginalis, the following are outstanding: it does not produce catalase, cytochrome oxidase, hydrogen sulphide, indole, or urease. Nor does it degrade aesculin, liquefy gelatin, reduce nitrate, or decarboxylate arginine, lysine or ornithine. On the other hand, it is sensitive to hydrogen peroxide, often causes beta-haemolysis and usually hydrolyses hippurate and starch. G. vaginalis is serologically heterogeneous and causes haemagglutination which is mannose resistant. It is resistant to several antibiotics, including amphotericin, colistin, nalidixic acid and gentamicin, which may be incorporated in selective media.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The bacteriology of Gardnerella vaginalis. 639 9

Hexokinase (ATP: D-hexose-6-phosphotransferase, EC 2.7.1.1) activity was determined in subcellular fractions prepared from pea (Pisum sativum) leaf homogenates. About 60% of the total detectable activity of hexokinase was found associated with a particulate fraction consisting essentially of mitochondria and chloroplasts and free of cytosol contamination. The hexokinase specific activity of the particulate fraction was 2-fold higher than that of the homogenate and about 4-fold higher than that of the cytosol. Using a specially designed isokinetic-isopycnic sucrose density gradient centrifugation method, the distribution of hexokinase activity correlated with that of the mitochondrial marker (cytochrome oxidase) and not with that of the chloroplast membrane marker ( chlorophyll ) or that of the cytosol marker (phosphoenolpyruvate carboxylase). Thus, the hexokinase/mitochondria ratio was close to 1.0 along the entire gradient, while the hexokinase/chloroplast ratio varied over a 10-fold range. The results strongly suggest that hexokinase is predominantly bound to mitochondria of pea leaves, and that pea leaf chloroplasts are essentially devoid of any specifically associated hexokinase activity. This work provides the first demonstration of a specific association of hexokinase with mitochondria from photosynthetic tissues of higher plants.
 ...
PMID:Subcellular localization of hexokinase in pea leaves. Evidence for the predominance of a mitochondrially bound form. 673 23

Washed human spermatozoa had an endogenous oxygen uptake of 2.14 +/- 0.17 nmol O2/10(8) spermatozoa/min (mean +/- s.e..m., n = 35) which was stimulated by succinate (Vmax = 9.64 +/- 0.44 nmol O2/10(8) spermatozoa/min) but not by other substrates. The ATP concentration in freshly washed spermatozoa was 12.18 +/- 0.54 (s.e.m.) nmol/10(8) spermatozoa (n = 26) and was maintained for 2 h in the presence of 2 mM-D-glucose but fell to 9.56 +/- 0.73 (s.e.m.) nmol/10(8) spermatozoa (n = 13) in its absence. The presence of 2 microM-antimycin A, 2 microM-rotenone, 0.4 microM-carbonyl cyanide m-chlorophenyl hydrazone or 8 microM-oligomycin caused the ATP concentration to fall to less than 2 nmol/10(8) spermatozoa but their effect was partly alleviated by 2 mM-glucose. Sodium malonate (5 mM) prevented the stimulation of respiration by succinate but had no effect on the ATP concentration of the spermatozoa or their ability to produce 14CO2 from [U-14C]glucose. The least active of the tricarboxylic acid cycle enzymes was 2-oxoglutarate dehydrogenase (EC 1.2.4.2) (3.1 +/- 0.6 (s.e.m.) nmol substrate transformed/10(8) spermatozoa/h (n = 4). Cytochrome c oxidase (EC 1.9.3.1) was much less active than in rat spermatozoa (22.3 +/- 6.0 (s.e.m., n = 4) and 615 +/- 87 (n = 4) nmol transformed/10(8) spermatozoa/min). It is concluded that human spermatozoa can obtain ATP by the respiration of endogenous substrate but the substrates and metabolic pathways involved remain obscure.
 ...
PMID:The role of oxidative phosphorylation in the generation of ATP in human spermatozoa. 727 30

Complete DNA sequences encoding the Arabidopsis thaliana STP1 monosaccharide/H+ symporter or a histidine-tagged STP1-His6 protein were expressed in baker's yeast Saccharomyces cerevisiae. Both wild-type STP1 and the recombinant his-tagged protein were located in the plasma membranes of transformed yeast cells. The C-terminal modification caused no loss of transport activity compared with the wild-type protein. Anti-STP1-antibodies were used to confirm the identity of the protein in yeast and to compare the apparent molecular weights of STP1 proteins in membrane extracts from yeast or Arabidopsis thaliana. Purified yeast plasma membranes were fused with proteoliposomes consisting of Escherichia coli lipids and beef heart cytochrome-c oxidase. Addition of ascorbate/TMPD/cytochrome-c to these fused vesicles caused an immediate formation of membrane potential (inside negative; monitored with [3H]tetraphenylphosphonium cations) and a simultaneous, uncoupler-sensitive influx of D-glucose into the energized vesicles. STP1-His6 protein is functionally active after solubilization with octyl-beta-D-glucoside, which was shown by insertion of the protein into proteoliposomes by detergent dilution and determination of the resulting transport capacity. Detergent extracts from either total membranes or plasma membranes of transgenic yeast cells were used for one-step purification of the STP1-His6 protein on Ni(2+)-NTA columns. The identity of the purified protein was checked by immunoblotting and N-terminal sequencing.
 ...
PMID:Functional reconstitution of the solubilized Arabidopsis thaliana STP1 monosaccharide-H+ symporter in lipid vesicles and purification of the histidine tagged protein from transgenic Saccharomyces cerevisiae. 792 Jul 12

An in vitro system was established to measure secondary active transport mediated by plant H+ symporters. For this purpose plasma membranes of Schizosaccharomyces pombe cells transformed with the HUP1 gene coding for the H+/hexose symporter of Chlorella kessleri were fused with cytochrome-c oxidase containing proteoliposomes. After energization with ascorbate/TMPD/cytochrome c these vesicles built up a protonmotive force of > 130 mV consisting mainly of a membrane potential of > 100 mV (inside negative). Energized vesicles accumulated D-glucose in a pH-dependent way up to 30-fold which was not the case with control vesicles prepared from cells transformed with the plasmid not containing the HUP1 gene. The Km value for D-glucose uptake was 5 x 10(-5) M. The pH-dependence of accumulation was not due to a difference in protonmotive force, but reflected the pH-dependence of the carrier activity, i.e., the accumulation was determined by kinetic and by thermodynamic parameters. In the system both components of protonmotive force delta psi and delta pH can be manipulated individually, which allows to evaluate to what extent they contribute to sugar accumulation. The results indicate that under certain conditions the internal pH may be a limiting factor for D-glucose accumulation.
 ...
PMID:The HUP1 gene product of Chlorella kessleri: H+/glucose symport studied in vitro. 807 29

This study compared the effects of aerobic exercise training and chronic administration of the selective beta 2-adrenergic agonist clenbuterol on whole body and skeletal muscle insulin resistance in obese (fa/fa) Zucker rats. Obese rats were randomly assigned to training, clenbuterol, or sedentary control groups. Lean littermates served as a second control group. After 4-5 wk of treatment, an oral glucose tolerance test was performed, followed 1 wk later by hindlimb perfusion, during which time the rates of glucose uptake and 3-O-methyl-D-glucose (3-MG) transport were assessed in the presence of a submaximal (500 microU/ml) insulin concentration. Training resulted in a significant increase in citrate synthase and cytochrome oxidase activity in the recruited muscles. Clenbuterol induced a large increase in muscle mass but provoked a significant decrease in oxidative enzyme activity and beta-adrenergic receptor density. Both treatments increased glucose tolerance and reduced the postglucose insulin response, with the improvements being more pronounced in the clenbuterol group. However, only exercise training improved insulin-stimulated hindlimb muscle glucose uptake (11.37 +/- 0.65, 8.73 +/- 0.77, and 8.27 +/- 0.41 mumol.g-1.h-1 for trained, clenbuterol, and sedentary control groups, respectively) and 3-MG transport. These results suggest that aerobic exercise training attenuated the insulin-resistant condition in the obese Zucker rat by a mechanism other than or in addition to beta 2-adrenergic receptor activation.
 ...
PMID:Exercise training and clenbuterol reduce insulin resistance of obese Zucker rats. 838 91

In this work, we developed and implemented a multimodality multidimensional imaging system which is capable of generating and displaying anatomical and functional images of selected structures and processes within a vertebrate's central nervous system (CNS). The functional images are generated from [14C]-2-deoxy-D-glucose (2DG) autoradiography whereas the anatomic images are derived from cytochrome oxidase (CO) histochemistry. This multi-modality imaging system has been used to study mechanisms underlying information processing in the rat brain. We have applied this technique to visualize and measure the plasticity (deformation) observed in the rat's whisker system due to neonatal lesioning of selected peripheral sensory organs. Application of this imaging system revealed detailed information about the shape, size, and directionality of selected cortical and subcortical structures. Previous 2-D imaging techniques were unable to deliver such holistic information. Another important issue addressed in this work is related to image registration problems. We developed an image registration technique which employs extrinsic fiduciary marks for alignment and is capable of registering images with subpixel accuracy. It uses the information from all available fiduciary marks to promote alignment of the sections and to avoid propagation of errors across a serial data set.
 ...
PMID:Multimodality multidimensional image analysis of cortical and subcortical plasticity in the rat brain. 873 64

The phenotypic effects of the human mitochondrial 12S rRNA gene mutation at position 1555 associated with maternally inherited non-syndromic deafness and sensitivity to aminoglycoside-induced deafness have been analyzed in 25 lymphoblastoid cell lines derived from members of a large family carrying this mutation in homoplasmic form and from control individuals. A clear decrease in the rates of growth in galactose medium, mitochondrial protein synthesis, total oxygen consumption, and complex I-, complex III- and complex IV-dependent respiration was observed in two groups of nine and 10 mutant cell lines derived, respectively, from symptomatic and asymptomatic members of the family, as compared with six control cell lines. The severity of mitochondrial dysfunction in the mutant cell lines was correlated with the presence or absence of hearing loss in the donor individuals. These observations strongly suggest a role of a nuclear factor(s) in the phenotypic manifestation of the mutation. The approach used here provides a paradigm for the analysis of the nuclear background involvement in other mtDNA-linked disorders, including the putative ones associated with neurodegenerative diseases. Exposure of the cell lines derived from several symptomatic or asymptomatic individuals from the same family to high concentrations of neomycin or paromomycin decreased to a significant, nearly identical extent their rate of growth in glucose-containing medium, as contrasted with the unchanged growth rate of control cell lines or of mtDNA-less cells. These results support the hypothesis that the main target of the antibiotics is the mitochondrial 12S rRNA carrying the 1555 mutation, without any apparent role of the nuclear background.
 ...
PMID:Biochemical evidence for nuclear gene involvement in phenotype of non-syndromic deafness associated with mitochondrial 12S rRNA mutation. 881 31


<< Previous 1 2 3 4 5 6 Next >>