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1.
Stereochemical structure recognized by the L-fucose-specific hemagglutinin produced by Streptomyces sp 总被引:1,自引:0,他引:1
A hemagglutinin has been purified 4000-fold from the culture filtrate of a strain of Streptomyces by affinity chromatography. The purified preparation was judged to be homogeneous by gel electrophoresis and its molecular weight was estimated to be about 70 000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It may exhibit its full hemagglutinating activity in the monomer form. This hemagglutinin strongly agglutinated human blood group O erythrocytes and was inhibited by L-fucose. It was, however, distinct from the known L-fucose-specific hemagglutinins; first, the hemagglutinating activity of the purified preparation was more than 100-times stronger than that of others; second, D-mannose was a potent inhibitor of this hemagglutinin besides L-fucose but not or scarcely inhibitory to others; and third, p-nitrophenyl-beta-L-fucoside was more inhibitory to this hemagglutinin than p-nitrophenyl-alpha-L-fucoside as opposed to the case of others. 相似文献
2.
ATP (1 mM) increased the phospholipase D (PLD) activity of rat submandibular gland (RSMG) ductal cells in a concentration-dependent and calcium-sensitive manner. The response to ATP was reproduced by benzoylbenzoyl-ATP (Bz-ATP, 100 microM) and also partly by adenosine 5'-(gamma-thio)triphosphate (ATPgammaS, 1 mM). A similar stimulation was observed in control mice (P2X7R+/+ mice) but not in mice lacking the P2X7 receptors (P2X7R-/- mice). Oxidized ATP and Coomassie blue or the addition of magnesium or nickel to the incubation medium inhibited the response to ATP. The stimulation of PLD by purinergic agonist was inhibited by about 50% by calphostin C and chelerythrine, two protein kinase C (PKC) inhibitors. The stimulation of PLD by Bz-ATP and by o-tetradecanoylphorbol 13-acetate (TPA), a phorbol ester which activates PKC, were not additive.From these results we can conclude that the activation of P2X7 receptors in RSMG ductal cells is coupled to the activation of a PLD. This activation is partly mediated by protein kinase C. 相似文献
3.
Marcela Aida González María del Carmen Contini Nestor Millen Stella Teresita Mahieu 《Cell biochemistry and function》2012,30(8):701-708
The process of regenerating liver is the result of a balance between stimulating factors and inhibitors of hepatocyte proliferation. Melatonin and its metabolites have been found to protect tissues against oxidative damage generated by a variety of toxic agents and metabolic processes. Furthermore, studies in liver of rats showed a decrease in the liver mitochondrial hydroxylation of drugs returning to the normal state after the administration of antioxidants. This study was designed to determine, in experimental animals, whether the administration of an antioxidant agent such as melatonin could prevent cells events leading to tissue injury and hepatic dysfunction after partial hepatectomy (PH). Biliary flow (BF), oxidative stress in hepatic tissue and Na+/K+ATPase activities in whole plasma membrane were determined. PH decreased the Na+/K+ATPase activity. PH significantly reduced the BF (36%) and promoted oxidative stress with an increase of lipoperoxidation and decrease of glutathione peroxidase and catalase activities. Treatment with melatonin prevented the decrease of BF in rats with hepatectomy and normalized the Na+/K+ATPase activity. Moreover, melatonin markedly attenuated oxidative stress produced by PH. This may be the results of the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes. We suggest that oxidative stress before and during liver regeneration has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage and the impairment in liver transport function induced by PH and that melatonin could modulate the degree of oxidative stress and through it prevent the alterations in liver function carrier. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
Abu-Baker A Laganiere S Fan X Laganiere J Brais B Rouleau GA 《Traffic (Copenhagen, Denmark)》2005,6(9):766-779
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disorder characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. The autosomal dominant form of this disease is caused by a polyalanine expansion from 10 to 12-17 residues, located at the N-terminus of the poly(A)-binding protein nuclear 1 (PABPN1). A distinct pathological hallmark of OPMD is the presence of filamentous intranuclear aggregates in patients' skeletal muscle cells. Wildtype PABPN1 protein is expressed ubiquitously and was shown to be mostly concentrated in discrete nuclear domains called 'speckles'. Using an established cell- culture model, we show that most mutant PABPN1- positive (alanine expanded form) intranuclear aggregates are structures distinct from intranuclear speckles. In contrast, the promyelocytic leukaemia protein, a major component of nuclear bodies, strongly colocalized to intranuclear aggregates of mutant PABPN1. Wildtype PABPN1 can freely shuttle between the nucleus and cytoplasm. We determined whether the nuclear environment is necessary for mutant PABPN1 inclusion formation and cellular toxicity. This was achieved by inactivating the mutant PABPN1 nuclear localization signal and by generating full-length mutant PABPN1 fused to a strong nuclear export sequence. A green fluorescence protein tag inserted at the N-terminus of both wildtype PABPN1 (ala10) and mutant PABPN1 (ala17) proteins allowed us to visualize their subcellular localization. Targeting mutant PABPN1 to the cytoplasm resulted in a significant suppression of both intranuclear aggregates formation and cellular toxicity, two histological consequences of OPMD. Our results indicate that the nuclear localization of mutant PABPN1 is crucial to OPMD pathogenesis. 相似文献
5.
Senka S. Vidović Ibrahim O. Mujić Zoran P. Zeković Žika D. Lepojević Vesna T. Tumbas Aida I. Mujić 《Food biophysics》2010,5(1):49-58
Considering the growing interest for mushrooms and the demand search of natural antioxidants sources, the aim of this study
was to investigate the antioxidant properties of two edible widely used Boletus species, Boletus edulis, and Boletus auranticus, collected from Istra region in Croatia in late summer 2007. To evaluate the antioxidant properties and content of antioxidant
compounds, scavenging capacity on DPPH˙, OH˙, and O2˙− radicals, reducing power and capacity to inhibit lipid peroxidation has been investigated. It is determined that content
of total phenols (41.82 ± 0.08 mg gallic acid equivalent per gram of dry extract) was higher for B. edulis. Using high performance liquid chromatography/diode array detector analysis, the main antioxidant compound, variegatic acid,
has been detected and quantified. 1,1-Diphenyl-2-picryl-hydrazyl-hydrate assay was used as a preliminary free radical–scavenging
evaluation. By this assay, it has been found that B. edulis dry mushroom extract exhibits 50% of inhibition value at the extract concentration of 0.016 ± 0.0003 mg/ml. The extracts
were capable of reducing iron(III) and, thus, are capable of donating electrons. Using electron paramagnetic resonance spin-trapping
and spin-probing techniques, activity against relevant reactive species, ˙OH and O2˙− radical, was analyzed for both mushroom extracts. Both investigated extracts are determined as good inhibitors for ˙OH radical
reduction, and both exhibited significant capacity for scavenging O2˙− radical and for that could help to prevent or meliorate oxidative damage. Only B. edulis extract prevents lipid peroxidation. Investigated mushroom extracts could represent easily accessible natural antioxidant
resource. 相似文献
6.
Seil M El Ouaaliti M Fontanils U Etxebarria IG Pochet S Dal Moro G Marino A Dehaye JP 《Purinergic signalling》2010,6(4):405-416
The response to ATP of peritoneal macrophages from wild-type (WT) and P2X7-invalidated (KO) mice was tested. Low concentrations (1–100 μM) of ATP transiently increased the intracellular concentration
of calcium ([Ca2+]i) in cells from both mice. The inhibition of the polyphosphoinositide-specific phospholipase C with U73122 inhibited this
response especially in WT mice suggesting that the responses coupled to P2Y receptors were potentiated by the expression of
P2X7 receptors. One millimolar ATP provoked a sustained increase in the [Ca2+]i only in WT mice. The response to 10 μM ATP was potentiated and prolonged by ivermectin in both mice. One millimolar ATP increased
the influx of extracellular calcium, decreased the intracellular concentration of potassium ([K+]i) and stimulated the secretion of interleukin-1β (IL-1β) only in cells from WT mice. Ten micromolar ATP in combination with
3 μM ivermectin reproduced these responses both in WT and KO mice. The secretion of IL-1β was also increased by nigericin
in WT mice and the secretory effect of a combination of ivermectin with ATP in KO mice was suppressed in a medium containing
a high concentration of potassium. In WT mice, 150 μM BzATP stimulated the uptake of YOPRO-1. Incubation of macrophages from
WT and KO mice with 10 μM ATP resulted in a small increase of YOPRO-1 uptake, which was potentiated by addition of 3 μM ivermectin.
The uptake of this dye was unaffected by pannexin-1 blockers. In conclusion, prolonged stimulation of P2X4 receptors by a combination of low concentrations of ATP plus ivermectin produced a sustained activation of the non-selective
cation channel coupled to this receptor. The ensuing variations of the [K+]i triggered the secretion of IL-1β. Pore formation was also triggered by activation of P2X4 receptors. Higher concentrations of ATP elicited similar responses after binding to P2X7 receptors. The expression of the P2X7 receptors was also coupled to a better response to P2Y receptors. 相似文献
7.
Covalent modifier NEDD8 is essential for SCF ubiquitin-ligase in fission yeast 总被引:6,自引:0,他引:6 下载免费PDF全文
Osaka F Saeki M Katayama S Aida N Toh-E A Kominami K Toda T Suzuki T Chiba T Tanaka K Kato S 《The EMBO journal》2000,19(13):3475-3484
A ubiquitin-like modifier, NEDD8, is covalently attached to cullin-family proteins, but its physiological role is poorly understood. Here we report that the NEDD8-modifying pathway is essential for cell viability and function of Pcu1 (cullin-1 orthologue) in fission yeast. Pcu1 assembled on SCF ubiquitin-ligase was completely modified by NEDD8. Pcu1(K713R) defective for NEDD8 conjugation lost the ability to complement lethality due to pcu1 deletion. Forced expression of Pcu1(K713R) or depletion of NEDD8 in cells resulted in impaired cell proliferation and marked stabilization of the cyclin-dependent kinase inhibitor Rum1, which is a substrate of the SCF complex. Based on these findings, we propose that covalent modification of cullin-1 by the NEDD8 system plays an essential role in the function of SCF in fission yeast. 相似文献
8.
Hona Hosseinpoor Aida Iraji Najmeh Edraki Somayeh Pirhadi Mahshid Attarroshan Mahsima Khoshneviszadeh Mehdi Khoshneviszadeh 《化学与生物多样性》2020,17(8)
Tyrosinase is a type 3 copper enzyme responsible for skin pigmentation disorders, skin cancer, and enzymatic browning of vegetables and fruits. In the present article, 12 small molecules of 2‐benzylidenehydrazine‐1‐carbothioamide were designed, synthesized and evaluated for their anti‐tyrosinase activities followed by molecular docking and pharmacophore‐based screening. Among synthesized thiosemicarbazone derivatives, one compound, (2E)‐2‐[(4‐nitrophenyl)methylidene]hydrazine‐1‐carbothioamide, is the strongest inhibitor of mushroom tyrosinase with IC50 of 0.05 μM which demonstrated a 128‐fold increase in potency compared to the positive control. Kinetic studies also revealed mix type inhibition by this compound. Docking studies confirmed the complete fitting of the synthesized compounds into the tyrosinase active site. The results underline the potential of 2‐benzylidenehydrazine‐1‐carbothioamides as potent pharmacophore to extend the tyrosinase inhibition in drug discovery. 相似文献
9.
Effect of Drying Medium on Residual Moisture Content and Viability of Freeze-Dried Lactic Acid Bacteria 总被引:4,自引:1,他引:4 下载免费PDF全文
Graciela F. de Valdez Graciela S. de Giori Aida P. de Ruiz Holgado Guillermo Oliver 《Applied microbiology》1985,49(2):413-415
The effect of various substances on the relationship between residual moisture content and the viability of freeze-dried lactic acid bacteria has been studied. Compounds such as polymers, which display considerable ability in displacing water, showed no protective action during freeze-drying. Adonitol, on the other hand, produced the smallest change in water content at various times during drying and allowed the highest rate of survival. 相似文献
10.