Bioenergetic
Mostrando 25-36 de 69 artigos, teses e dissertações.
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25. Correlation of bioenergetic parameters with cell death in Listeria monocytogenes cells exposed to nisin.
In Listeria monocytogenes, nisin induced ATP efflux, reduced the intracellular ATP concentration within 1 min, and dissipated the proton motive force within 2 min. Efflux accounted for only 20% of the ATP depletion, suggesting that ATP hydrolysis also occurred. ATP efflux depended on nisin concentration and followed saturation kinetics. These results suggest
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26. Incorporation of specific exogenous fatty acids into membrane lipids modulates protonophore resistance in Bacillus subtilis.
Attempts to manipulate the level of C16:1 fatty acids in membrane phospholipids were made by using Bacillus subtilis and its protonophore-resistant mutants to test the hypothesis that C16:1 fatty acid levels relate to the bioenergetic properties of the mutant strains. Growth of the three mutants in the presence of palmitoleic acid restored the level of C16:1
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27. Enzymatic basis for bioenergetic differences of alveolar versus peritoneal macrophages and enzyme regulation by molecular O2.
Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different O2 environments. In the present studies, the impact of different O2 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differenc
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28. Theoretical aspects of translocation on DNA: adenosine triphosphatases and treadmilling binding proteins.
The basic kinetic and bioenergetic theory is outlined for two kinds of translocation on DNA: (i) helicases that use ATP to move along single-stranded DNA or to move on and invade double-stranded DNA at a replication fork; and (ii) DNA-binding proteins (not ATPases) that form bound aggregates on single-stranded DNA and facilitate replication by steady-state t
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29. Biosynthetic and Bioenergetic Functions of Citric Acid Cycle Reactions in Rhodopseudomonas capsulata
Rhodopseudomonas capsulata can grow in a number of alternative modes, including (i) photosynthetic, defined here as anaerobic growth with light as the energy source, and (ii) heterotrophic, referring to aerobic heterotrophic growth in darkness. The functions of citric acid cycle sequences in these growth modes were investigated using wild-type and appropriat
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30. Microfilament or microtubule assembly or disassembly against a force.
Microtubules (tubulin) or bundles of microfilaments (actin) are thought to cause movement, in some instances, by disassembly or assembly of subunits. Possible examples are the pulling of a chromosome toward a pole in mitosis (anaphase) or the deformation of a cell membrane to change the shape of a cell. This paper examines the relevant elementary bioenergeti
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31. Bioenergetic aspects and polymer length distribution in steady-state head-to-tail polymerization of actin or microtubules.
Wegner's theory of steady-state head-to-tail polymerization of actin (or microtubules) is extended somewhat in order to show the explicit role of the ATP (or GTP) free energy of hydrolysis (X) in the steady-state kinetics. The monomer flux and the ATP flux can both be expressed in terms of X and rate constants of the model. Both fluxes approach zero as X lea
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32. Cyclic adenosine 3',5'-monophosphate regulation of membrane energetics in Escherichia coli.
Mutants of Escherichia coli K-12 lacking functional adenylate cyclase (cya) or the cyclic adenosine 3',5'-monophosphate (cAMP) receptor protein (crp) were compared with their wild type to evaluate the role played by the cAMP-cAMP receptor protein complex in regulating this organism's membrane-associated bioenergetic functions. Both mutants were found to be e
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33. High phosphorylation efficiency and depression of uncoupled respiration in mitochondria under hypoxia
Mitochondria are confronted with low oxygen levels in the microenvironment within tissues; yet, isolated mitochondria are routinely studied under air-saturated conditions that are effectively hyperoxic, increase oxidative stress, and may impair mitochondrial function. Under hypoxia, on the other hand, respiration and ATP supply are restricted. Under the
The National Academy of Sciences.
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34. Noninvasive, nondestructive approaches to cell bioenergetics.
To demonstrate the feasibility of using NMR spectra of human limbs and larger animals for continuous, noninvasive, nondestructive evaluation of cell bioenergetics, we have constructed a relatively simple and inexpensive 31P NMR apparatus. This apparatus consists of an 18-cm (7-in.) bore superconducting magnet and appropriate transmit-receive components for F
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35. Subunit treadmilling of microtubules or actin in the presence of cellular barriers: possible conversion of chemical free energy into mechanical work.
Free microtubule or actin filaments, along with the monomeric forms of the protein, hydrolyze GTP or ATP to produce a flux of subunits through the polymer. This flux, called treadmilling, produces no useful work. In the cell, however, these filaments are likely to be constrained between nucleating sites and other barriers that will limit polymer growth. We s
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36. Bioenergetic properties of alkalophilic Bacillus sp. strain C-59 on an alkaline medium containing K2CO3.
Alkalophilic Bacillus sp. strain C-59 could grow well on an alkaline medium containing K2CO3, as well as Na2CO3, but did not grow on K+-depleted medium. Right-side-out membrane vesicles, energized in the absence of Na+, however, could not take up [14C]methylamine actively, while vesicles equilibrated with 10 mM NaCl actively took up [14C]methylamine. The upt