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  • 1
    Electronic Resource
    Electronic Resource
    ATP-dependent H+-pumping of a low-density fraction of pea stem microsomes (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 71 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A low-density fraction of pea (Pisum sativum L. cv. Alaska) stem microsomes, obtained from a discontinuous sucrose gradient, possessed an H+-ATPase able to generate a proton gradient and an electrical potential. The proton pumping was insensitive to monovalent cations, to vanadate and oligomycin, required a permeant anion and was inhibited by nitrate, N, N'-dicyclohexylcarbodiimide and diethylstilbestrol. The H+-ATPase had a pH optimum around 6.0–6.5 and was saturable with respect to the substrate Tris-ATP (Km≅ 0.4 mM). Ca2+ (0.05–1 mM) induced a dissipation of the ATP-generated δpH without affecting ATPase activity. At physiological concentrations (1–5 mM), nitrate caused an initial slight increase of the ATP-generated proton gradient followed by a complete dissipation after 2–3 min. The dissipating effect was not caused by inhibition of ATPase activity, since ATP prevented the nitrate-induced collapse of δpH. On the other hand, ATPase activity, evaluated as release of Pi, was not inhibited by concentrations lower than 20 mM KNO3. These results indicate that nitrate entered the vesicles in response to an electrical potential and then could exit in symport with protons, while Ca2+ entered in exchange for protons (antiport).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb04614.x
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  • 2
    Electronic Resource
    Electronic Resource
    K+ATP channel opening prevents succinate-dependent H2O2 generation by plant mitochondria (2003)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 118 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of a recently identified K+ATP channel in preventing H2O2 formation was examined in isolated pea stem mitochondria. The succinate-dependent H2O2 formation was progressively inhibited, when mitochondria were resuspended in media containing increasing concentration of KCl (from 0.05 to 0.15 M). This inhibition was linked to a partial dissipation of the transmembrane electrical potential (ΔΨ) induced by KCl. Conversely, the malate plus glutamate-dependent H2O2 formation was not influenced. The succinate-sustained H2O2 generation was also unaffected by nigericin (a H+/K+ exchanger), but completely prevented by valinomycin (a K+ ionophore). In addition, cyclosporin A (a K+ATP channel opener) inhibited this H2O2 formation, while ATP (an inhibitor of the channel opening) slightly increased it. The inhibitory effect of ATP was strongly stimulated in the presence of atractylate (an inhibitor of the adenine nucleotide translocase), thus suggesting that the receptor for ATP on the K+ channel faces the intermembrane space. Finally, the succinate-dependent H2O2 formation was partially prevented by phenylarsine oxide (a thiol oxidant).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00109.x
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  • 3
    Electronic Resource
    Electronic Resource
    H+/PPi stoichiometry of a membrane-bound pyrophosphatase of plant mitochondria (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The H+/PPi stoichiometry of the mitochondrial H+-PPiase from pea (Pisum sativum L.) stem was determined by two kinetic approaches, and compared with the H+/substrate stoichiometries of the mitochondrial H+-ATPase, and the vacuolar H+-PPiase and H+-ATPase. Using sub-mitochondrial particles or preparations enriched in vacuolar membranes, the rates of substrate-dependent H+-transport were evaluated: by a mathematical model, describing the time-course of H+-gradient (ΔpH) formation; or by determining the rate of H+-leakage following H+-pumping inhibition by EDTA at the steady-state ΔpH. When the H+-transport rates were divided by those of PPi or ATP hydrolysis, measured under identical conditions, apparent stoichiometries of ca 2 were determined for the mitochondrial H+-PPiase and H+-ATPase, and for the vacuolar H+-ATPase. The stoichiometry of the vacuolar H+-PPiase was found to be ca 1. From these results, it is suggested that the mitochondrial H+-PPiase may, in theory, function as a primary H+-pump poised towards synthesis of PPi and, therefore, acting in parallel with the main H+-ATPase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030302.x
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  • 4
    Electronic Resource
    Electronic Resource
    Pyrophosphate import and synthesis by plant mitochondria (2002)
    Oxford, UK : Blackwell Science, Ltd
    Physiologia plantarum 114 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The matrix level of pyrophosphate (PPi) in mitochondria isolated from etiolated pea (Pisum sativum L. cv. Alaska) stems was evaluated, on the basis of an enzymatic assay, to be approx. 0.2 mM. Pyrophosphate could enter from the cytoplasm to the mitochondria via adenine nucleotide translocase (ANT), because F– and Ca2+ (two penetrating PPiase inhibitors) and atractylate (ANT inhibitor) inhibited PPiase activity in isolated mitochondria supplied with PPi. This result was also confirmed by measuring oxygen consumption and membrane potential (ΔΨ) in succinate-energized mitochondria. In a medium free of phosphate (Pi), the addition of PPi before the substrate rendered possible an ADP-stimulated oxygen consumption that was inhibited by F– or Ca2+. In a similar experiment, ADP induced the dissipation of ΔΨ when it was added after the succinate-generated ΔΨ had reached a steady state and, again, F– inhibited this dissipation. These results imply that PPi enters the mitochondria where it is hydrolyzed to 2 Pi which become available for the H+-ATPase (EC 3.6.1.34). In addition, PPi may be synthesized by the H+-PPiase (EC 3.6.1.1), acting as a synthase. This evidence arises from the observation that Pi stimulated an oxygen consumption (respiratory control ratio of 1.7) that was inhibited by F– or Ca2+. The physiological role of the mitochondrial H+-PPiase is discussed in the light of the consideration that this enzyme can catalyse a readily reversible reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1140403.x
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  • 5
    Electronic Resource
    Electronic Resource
    Proton pumping pyrophosphatase from higher plant mitochondria (1999)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 105 (1999), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In higher plant cells, there are some enzymes capable of utilizing pyrophosphate (PPi) as an energy donor. Among these, membrane-bound proton pumping pyrophosphatases (H+-PPiase) have been identified. In addition to the well-known vacuolar H+-PPiase (V-PPiase), there is evidence for the presence of a mitochondrial H+-PPiase. This enzyme is localized on the inner surface of the inner membrane and catalyzes the specific hydrolysis of PPi, coupled to proton transport, with a H+/PPi stoichiometry of ca 2. This activity is Mg2+-requiring, is stimulated by monovalent cations, and is inhibited by Ca2+, F− and diphosphonates. The H+-PPiase contains a catalytic head which is constituted by a 35-kDa protein which is loosely bound to the inner membrane. This protein exhibits a PPiase activity, stimulated by phospholipids, with characteristics very similar to the membrane-bound enzyme. The mitochondrial PPiase is distinct from the V-PPiase, because an antibody raised against the 35-kDa protein does not react with tonoplast membranes. The mitochondrial H+-PPiase seems to have an F-type structure, similar to the F-ATP synthase and the membrane-bound PPiases from mammalian and yeast mitochondria. It is suggested that, beside synthesizing PPi, this enzyme may act as a buffer for the electrochemical proton gradient, by hydrolyzing PPi, during conditions of oxygen deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1999.105422.x
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  • 6
    Electronic Resource
    Electronic Resource
    Salicylate-collapsed membrane potential in pea stem mitochondria (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 67 (1986), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Salicylate, acetylsalicylate, benzoate and 3,5-diiodosalicylate were examined for their effects on pea (Pisum sativum L. cv. Alaska) stem mitochondria and on a tonoplast-enriched fraction. Salicylate collapsed the transmembrane electrochemical potential of mitochondria and the ATP-dependent proton gradient of the tonoplast-enriched vesicle preparation. Benzoate and acetylsalicylate did not show any effect, while 3,5-diiodosalicylate inhibited both basal O2 consumption and ATPase activity of pea mitochondria. Salicylate seems to act as a protonophore. However, its effect is evident only at concentrations higher than those required by classical protonophores and, in addition, can be abolished after removing salicylate from the incubation medium. The activity of salicylate appears linked to the presence of the free phenolic hydroxyl on the benzene ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1986.tb02434.x
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  • 7
    Electronic Resource
    Electronic Resource
    Generation of superoxide anion and hydrogen peroxide at the surface of plant cells (1991)
    Springer
    Journal of bioenergetics and biomembranes 23 (1991), S. 409-423 
    Details
    ISSN: 1573-6881
    Keywords: Anion superoxide ; cell wall ; hydrogen peroxide ; NADH oxidase ; plant cell ; plasma membrane ; surface peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract In addition to well-known cell wall peroxidases, there is now evidence for the presence of this enzyme at the plasma membrane of the plant cells (surface peroxidase). Both are able to catalyze, through a chain of reactions involving the superoxide anion, the oxidation of NADH to generate hydrogen peroxide. The latter is oxidized by other wall-bound peroxidases to convert cinnamoyl alcohols into radical forms, which, then polymerize to generate lignin. However, there are other enzymes at the surface of plasma membranes capable of generating hydrogen peroxide (cell wall polyamine oxidase), superoxide anion (plasma membrane Turbo reductase), or both (plasma membrane flavoprotein?). These enzymes utilize NAD(P)H as a substrate. The Turbo reductase and the flavoprotein catalyze the univalent reduction of Fe3+ and then of O2 to produce Fe2+ and $$O_2^{\bar \cdot } $$ , respectively. The superoxide anion, in the acidic environment of the cell wall, may then dismutate to H2O2. These superoxide anion- and hydrogen peroxide-generating systems are discussed in relation to their possible involvement in physiological and pathological processes in the apoplast of plant cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00771012
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  • 8
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    Mitochondrial bioenergetics linked to the manifestation of programmed cell death during somatic embryogenesis of Abies alba (2009)
    Springer
    Details
    Publication Date: 2009-10-16
    Print ISSN: 0032-0935
    Electronic ISSN: 1432-2048
    Topics: Biology
    Published by Springer
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  • 9
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    Generation of superoxide anion and hydrogen peroxide at the surface of plant cells (1991)
    Springer
    Details
    Publication Date: 1991-06-01
    Print ISSN: 0145-479X
    Electronic ISSN: 1573-6881
    Topics: Biology , Chemistry and Pharmacology , Physics
    Published by Springer
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  • 10
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    Protein Hydrolysates from Anchovy (Engraulis encrasicolus) Waste: In Vitro and In Vivo Biological Activities (2020)
    Molecular Diversity Preservation International
    Details
    Publication Date: 2020-01-28
    Description: Fish waste utilization to obtain protein hydrolysates has been demonstrated to be a useful strategy to face both environmental and economic impacts while obtaining high-value products with remarkable biological and nutritional properties. In the present study, protein hydrolysates obtained from anchovy Engraulis encrasicolus (APH) by-products were assessed for their potential biological activities in both in vitro and in vivo models. The treatment with APH exerted a significant protection against LPS-induced inflammation in RAW 264.7 cells, decreasing the protein expression of pro-inflammatory mediators (i.e., COX-2) and inhibiting the nuclear translocation of NF-κB through IκB-α. Moreover, APH modulated the expression of iNOS, MnSOD and HO-1, thus decreasing the severity of oxidative stress. The supplementation of APH in the diet of ApoE knockout mice down-regulated the proinflammatory cytokines (i.e., TNF-α, IL-1α, IL-1β, IL-6) in both aorta and heart tissues, and modulated the expression of oxidative stress-related genes (Cu/ZnSod, MnSod, Cat, Gpx and Ho), indicating that APH can exert a beneficial role, having anti-inflammatory and antioxidant activities. The nutritional properties of APH, together with their biological activities herein reported, highlight the possibility of obtaining bioactive molecules from fish waste and encourage their use as potential nutraceuticals in food and pharmaceutical industries in the next future.
    Electronic ISSN: 1660-3397
    Topics: Chemistry and Pharmacology
    Published by Molecular Diversity Preservation International
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