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1.
The rate of H+-induced Na/H-exchange in erythrocytes of patients with occlusive and with floating types of acute deep venous thromboses, and in control volunteers, was estimated. In patients with occlusive thrombi Na/H-exchange was revealed to be fourfold higher in comparison with patients with floating thrombi and with controls, while no difference was observed between the two latter groups.  相似文献   

2.
Oncogenic transformation involves reprogramming of cell metabolism, whereby steady-state levels of intracellular NAD+ and NADH can undergo dramatic changes while ATP concentration is generally well maintained. Altered expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD+-salvage, accompanies the changes in NAD(H) during tumorigenesis. Here, we show by genetic and pharmacological inhibition of NAMPT in glioma cells that fluctuation in intracellular [NAD(H)] differentially affects cell growth and morphodynamics, with motility/invasion capacity showing the highest sensitivity to [NAD(H)] decrease. Extracellular supplementation of NAD+ or re-expression of NAMPT abolished the effects. The effects of NAD(H) decrease on cell motility appeared parallel coupled with diminished pyruvate-lactate conversion by lactate dehydrogenase (LDH) and with changes in intracellular and extracellular pH. The addition of lactic acid rescued and knockdown of LDH-A replicated the effects of [NAD(H)] on motility. Combined, our observations demonstrate that [NAD(H)] is an important metabolic component of cancer cell motility. Nutrient or drug-mediated modulation of NAD(H) levels may therefore represent a new option for blocking the invasive behavior of tumors.  相似文献   

3.
10 mM isatin (2,3-dioxoindole) inhibited glucose influx into human erythrocytes by over 30%. The inhibition is of the competitive type, where the affinity constant (Kt) was increased from 5.71 (control) to 11.11 mM in the presence of isatin with no change in Vmax (130 nmol/min/ml packed cells). The observed inhibition of sugar transport by isatin was not mediated through membrane–SH groups accessible to iodoacetate, iodoacetamide, DTNB, DNP or sodium arsenite. Isatin inhibited sugar transport in the presence of 2 mM harmaline, an alkaloid inhibitor of Na+, K+–ATPase activity. The inhibition was non additive which suggests that these two compounds interact with the same or a similar site on the erythrocyte membrane.  相似文献   

4.
The exposure of phosphatidylserine (PS) at the cell surface plays a critical role in blood coagulation and serves as a macrophage recognition moiety for the engulfment of apoptotic cells. Previous observations have shown that a high extracellular [K+] and selective K+ channel blockers inhibit PS exposure in platelets and erythrocytes. Here we show that the rate of PS exposure in erythrocytes decreases by ~50% when the intracellular [K+] increases from 0 to physiological concentrations. Using resealed erythrocyte membranes, we further show that lipid scrambling is inducible by raising the intracellular [Ca2+] and that K+ ions have a direct inhibitory effect on this process. Lipid scrambling in resealed ghosts occurs in the absence of cell shrinkage and microvesicle formation, processes that are generally attributed to Ca2+-induced lipid scrambling in intact erythrocytes. Thus, opening of Ca2+-sensitive K+ channels causes loss of intracellular K+ that results in reduced intrinsic inhibitory effect of these ions on scramblase activity. Received 11 September 2008; received after revision 17 October 2008; accepted 27 October 2008  相似文献   

5.
Summary The O2– and Ca2+-paradoxes have a number of features in common and it is suggested that release of cytosolic proteins in both paradoxes is initiated by the activation of a sarcolemma NAD(P)H dehydrogenase which can generate a transmembrane flow of H+ and e and also oxygen radicals or recox cycling which damage ion channels and membrane proteins (phase I). Entry of Ca2+ through the damaged ion channels then exacerbates the damage by further activating this system, either directly or indirectly, and the redox cycling and/or oxygen radicals cause further damage to integral and cytoskeletal proteins of the sarcolemma resulting in microdamage to the integrity of the membrane (phase II) and the consequent release or exocytosis of cytoplasmic proteins and, under specialised condition, the blebbing of the sarcolemma. The system may be primed either by removal of extracellular Ca2+ or by raising [Ca2+]i by a variety of measures, these two actions being synergistic. The system is initially activated in the Ca2+-paradox by the membrane perturbation associated with removal of extracellular Ca2+; prolonged anoxia in the metabolically active cardiac muscle causes a depletion of the ATP supply, particularly in the absence of glucose, and hence a rise in [Ca2+]i in phase I of the oxygen paradox with the consequent activation of the NAD(P)H oxidase at the sarcolemma. Oxygen radicals are probably generated in both paradoxes and may have a partial role in the genesis of damage, but are not essential in the Ca2+-paradox which continues under anoxia. Massive entry of Ca2+ also activates an intracellularly localised dehydrogenase (probably at the SR) which produces myofilament damage by redox cycling.  相似文献   

6.
Summary Nicotinamide adenine dinucleotide phosphate phosphomonoesterase was isolated and partially purified from wheat (Triticum aestivum L. var. Selkirk) leaves. The enzyme hadK NADP value of 1.4×10–4 M and a pH optimum of 5.9.In vitro activity of this enzyme was unaffected by precursors of NAD (nicotinamide and nicotinic acid) or cytokinis (kinetin and benzimidazole). However, when detached wheat leaves were treated with solutions of these compounds, the precursors lowered the specific activity while the cytokinins enhanced the activity. It is suggested that spatial separation and compartmentation of the enzyme and its substrate NADP account for the similar effect of benzimidazole on both.This work was supported by a grant No. A2698 from the National Research Council, Canada.  相似文献   

7.
To evaluate how chloroquine kills malaria parasites, hemoglobin catabolism was studied at the various stages of intraerythrocytic parasite development. We found that hemoglobin catabolism is switched off whenPlasmodium falciparum parasites mature to the late trophozoite or early schizont stages and is switched on again during the ring stage. When hemoglobin catabolism is switched off, the parasites are resistant to the morphologic effects of chloroquine. Although the ring stage parasites failed to mature in the presence of chloroquine, some of them switched on hemoglobin ingestion and became stuffed with hemoglobin-filled vesicles, indicating a distal block in catabolism. In fact, we demonstrated a high-grade block in hemozoin production during a 22 h incubation of synchronized ring forms; ferriprotoporphyrin IX (FP) incorporation into the -hematin of hemozoin decreased from 900 to 50 pmol/106 parasitized erythrocytes. We propose that the primary effect of chloroquine on hemoglobin catabolism is to block FP polymerization to -hematin. Secondarily, toxic FP and FP-chloroquine complexes accumulate and are available to exert their several toxicities, which include inhibition of hemoglobindegrading proteases and membrane damage. As a consequence, maturation is arrested and eventually the parasites die and lyse.  相似文献   

8.
Zusammenfassung Der Einfluss der Azidose auf die Glykolyse der Erythrozyten wurde in vitro untersucht. Es resultiert eine Erniedrigung der Milchsäureproduktion bei gleichzeitiger Erhöhung des Glukose-6-Phosphat-Gehalts und des Laktat/Pyruvat/Quotienten. Die Befunde weisen auf eine direkte Beeinflussung der Glykolyse infolge verändertem NAD/NADH-Redox-Zustand durch erhöhte H+-Konzentration.  相似文献   

9.
Summary From the spongeHaliclona chilensis (Thiele) a minor keto-sterol was isolated and characterized as 24-keto-cholesta-5,25-dien-3-ol by means of spectroscopic (1H and13C-FT NMR, MS) methods.  相似文献   

10.
Summary The mechanism of incorporation of different mental ions into phthalocyaninetetrasulfonic acid in aqueous solution has been investigated. It was found that the rate of the reacion with Cu2+ depends on the dissociation rate of the N-H-bond of this porphyrin-like chelating agent, whereas the reaction rate with other metal ions, like Zn2+, does not.

II. Mitt. Siehe I. Mitt.:K. Bernauer undS. Fallab, Helv.44, 1287 (1961).

Herrn Prof. Dr.H. Erlenmeyer sind wir für sein reges Interesse an dieser Arbeit zu bestem Dank verpflichtet.  相似文献   

11.
Direct observations of the enzymatic hydrolysis of C10 acyclic allylic isoprenyl diphosphates by an acid phosphatase from the leaves ofCinnamomum camphora (camphor tree) were made using1H and31P NMR spectrometers. The measurements indicated that the allylic primary diphosphates, geranyl diphosphate and neryl diphosphate, were hydrolyzed to their corresponding alcohols in a sequential manner via their corresponding monophosphates, whereas the allylic tertiary diphosphate, linalyl diphosphate, was hydrolyzed only to its corresponding monophosphate.  相似文献   

12.
Summary The presence of an oxalate oxidase (EC 1.2.3.4) has been demonstrated in 15,000×g supernatants prepared from 10-day-old seedlings of three genotypes ofSorghum vulgare: grain sorghum hybrid (CSH-5), grain-cum-forage sorghum (PC-6) and forage sorghum (PC-1). The specific activity of the enzyme in the different tissues of seedlings was found to be present in the order leaves > stems > roots in PC-6 and PC-1, but this order was reversed in CSH-5. A comparison of the different properties of the leaf enzyme of these three genotypes of sorghum revealed that the enzyme has maximum activity in the acidic pH range from 4.0 to 5.0 and in the temperature range from 37°C to 40°C. The enzyme was stimulated by Cu2+ and Fe2+. The rate of H2O2 formation in the enzyme reaction was linear up to 5 min and was stoichiometrically related to oxalate consumption. The enzyme is unaffected by Na+ at physiological concentration (0.15 M). The superiority of this enzyme over moss and other plant enzymes for enzymic determination of urinary oxalate is discussed.  相似文献   

13.
Poly-ADP-ribose polymerases (PARPs) use NAD+ as substrate to generate polymers of ADP-ribose. We targeted the catalytic domain of human PARP1 as molecular NAD+ detector into cellular organelles. Immunochemical detection of polymers demonstrated distinct subcellular NAD+ pools in mitochondria, peroxisomes and, surprisingly, in the endoplasmic reticulum and the Golgi complex. Polymers did not accumulate within the mitochondrial intermembrane space or the cytosol. We demonstrate the suitability of this compartment-specific NAD+ and poly-ADP-ribose turnover to establish intra-organellar protein localization. For overexpressed proteins, genetically endowed with PARP activity, detection of polymers indicates segregation from the cytosol and consequently intra-organellar residence. In mitochondria, polymer build-up reveals matrix localization of the PARP fusion protein. Compared to presently used fusion tags for subcellular protein localization, these are substantial improvements in resolution. We thus established a novel molecular tool applicable for studies of subcellular NAD metabolism and protein localization.  相似文献   

14.
Summary Cu2+-complexes with different monodentate ligands PYR, e.g. pyridine, 2,4,6-collidine and imidazole, catalyse the oxidation ofo-phenylenediamine (H2B) to 3,5-dihydro-2-amino-3-iminophenazine (PHEN) by O2. Investigation of the electron paramagnetic resonance during reaction gives interesting details on the function of Cu2+ as a catalyser. The formation of mixed complexes (H2B)Cu2+(PYR) and its influence on the reaction rated[PHEN]/dt is demonstrated. In the ratedetermining reaction, Cu2+ is reduced to Cu+, which is reoxidized by O2. During reaction the ratio [Cu2+]/[Cu+] is determined by means of e.p.r. measurements.  相似文献   

15.
Summary D-3-Dodecanoyltetradecanoic acid has been separated from the lipid A ofYersinia pseudotuberculosis and its structure has been established by chromato-mass-spectrometry and13C NMR spectroscopy, by comparison with authentic samples.  相似文献   

16.
The tritium-labeled bis-norleucine analog ofHelicoverpa zea pheromone biosynthesis-activating neuropeptide ([3H]NLPBAN) was incubated in vitro with hemolymph fromManduca sexta orH. zea adult females. The incubations resulted in the formation of several tritium-labeled degradation products. At a [3H]NLPBAN concentration of 0.9 μM the degradation proceeded at a very slow but physiologically plausible rate (2–10 fmol/min/μl hemolymph). The primary [3H]NLPBAN degradation reaction inM. sexta hemolymph was not inhibited by 20 μM leupeptin, 0.1 mM amastatin, 1 mM EDTA, 1 mM EGTA, 1 mM 1,10-phenanthroline, or 2 mM 4-(2-aminoethyl)benzenesulfonyl fluoride; but secondary reactions may have been affected, as some of the inhibitors changed the radio-HPLC profile of the degradation products. It is concluded that hemolymph ofM. sexta andH. zea contains peptidase(s) capable of inactivating circulating PBAN.  相似文献   

17.
Summary Na+, K+-ATPase inhibitors extracted from plasma of healthy human subjects displaced3H-ouabain binding to human erythrocytes and inhibited the Na+ efflux catalyzed by the Na+, K+-pump and unexpectedly the Na+, K+-cotransport system without alteration of the Na+, Na+-exchange or the Na+ passive permeability. This suggests the presence in healthy human plasma of endogenous factors with ouabain-like and furosemide-like activities.Acknowledgments. We are indebted to Dr M. A. Devynck for her advice on chemical measurements and to Dr R. P. Garay for his help with flux measurements  相似文献   

18.
The nest cell lining ofHylaeus bisinuatus (Hymenoptera: Colletidae) was shown by high-resolution solidstate [13C]NMR to be composed of lipid polymer and protein. The lipid polymer was shown by reduction and subsequent GC/MS analysis to be comprised of -hydroxy fatty acids (C20, C22, C24 and C26) and fatty alcohols (C16 to C30). The protein portion of the lining had a silk-like amino acid composition.  相似文献   

19.
A rapid, sensitive and simple spectrophotometric method for the detection of1O2 produced by photodynamic photosensitizers in slightly acid and air-saturated aqueous solutions has been developed. The method is based on the reaction of1O2 (produced by photodynamic processes) with I in the presence of ammonium molybdate as a catalyst. The reaction product I3 , proportional to1O2, is followed spectrophotometrically at 355 nm. Several ways of avoiding interference with other oxidizing compounds, either present before or produced during the irradiation, are described.The method could be used to measure the efficiency of water-soluble photodynamic photosensitizers.  相似文献   

20.
Summary The effect of adrenaline on the Na+-pump in bullfrog (Rana catesbeiana) sympathetic ganglion cells was studied by use of electrophysiological methods. The rate of removal of excess Na+ injected into a ganglion cell was increased by adrenaline. The K+-activated hyperpolarization of cell membrane, which might be produced by an electrogenic Na+-pump, was also increased by adrenaline. These results suggested that adrenaline was able to accelerate the Na+-pump, possibly the electrogenic Na+-pump.  相似文献   

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