共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Chatterjee K. K. Mukherjee M. C. Mondal S. K. Chakravarti M. S. Chakraborty 《Folia microbiologica》1995,40(3):345-348
A study was undertaken with a view to assess the distinct pattern of sero-prevalence of influenza A viruses in the city of
Calcutta population during the years of 1981–90. Concurrently, based on the fact of increasing pig population, a study was
carried out to establish the activity of the human influenza A virus among pigs with a view to the potential threat of emergence
of a new strain of influenza A virus that may surface following co-infection with swine and human influenza A viruses. The
percentage positivity of the H3N2 antigen was found to be highest (46%), followed by H1N1 (43%), H2N2 (35%) and H0N1 (19%). A similar pattern was noted with pig sera. 相似文献
2.
Milena Popovi? Joycelynn D. Nelson Kersten T. Schroeder Nancy L. Greenbaum 《RNA (New York, N.Y.)》2012,18(11):2093-2103
The branch site helix from Saccharomyces cerevisiae with pseudouridine (ψ) incorporated in a phylogenetically conserved position of U2 snRNA features an extrahelical branch site adenosine (A) that forms a base triple interaction with the minor groove edge of a widely conserved purineU2 strand-pyrimidineintron strand (RU2-Yintron) base pair two positions upstream. In these studies, NMR spectra of a duplex in which 2-aminopurine (2ap), a fluorescent analog of adenine lacking the proposed hydrogen bond donor, was substituted for the branch site A, indicated that the substitution does not alter the extrahelical position of the branch site residue; thus, it appears that a hydrogen bond between the adenine amino group and the R-Y pair is not obligatory for stabilization of the extrahelical conformation. In contrast, reversal of the orientation of AU2-Uintron to UU2-Aintron resulted in an intrahelical position for the branch site A or 2ap. Fluorescence intensity of 2ap substituted for the branch site A with the original RU2-Yintron orientation (AU or GC) was high, consistent with an extrahelical position, whereas fluorescence in helices with the reversed R-Y orientation, or with a mismatched pair (A-U → G•A or U•C), was markedly quenched, implying that the residue was stacked in the helix. The A 5′ to the branch site residue was not extrahelical in any of the duplexes. These findings suggest that the RU2-Yintron base pair orientation in the ψ-dependent branch site helix plays an important role in positioning the branch site A for recognition and/or function. 相似文献
3.
Kenneth M. Newrock Neil Freedman Candido Rodriguez Alfageme Leonard H. Cohen 《Developmental biology》1982,89(1):248-253
H2Aα1, the principal H2A histone synthesized prior to the blastula stage of the sea urchin, was isolated free of other putative H2A subtypes and other histones. Its amino acid composition provides confirmation that H2Aα1 is the H2A protein encoded in the histone gene cluster carried by pCO2. An antibody prepared against this protein cross-reacts strongly with CS2A (a putative H2A synthesized only during the cleavage stage) as well as with H2Aβ, H2Aγ, and H2Aδ (putative H2As synthesized principally after the blastula stage) but not with non-H2A core histones or other nuclear proteins. The data support the view that CS2A, H2Aα1, H2Aβ, H2Aγ, and H2Aδ are all H2A proteins. 相似文献
4.
Kazuma Ogawa Katsuichi Ohtsuki Tomomi Shibata Miho Aoki Morio Nakayama Yoji Kitamura Masahiro Ono Masashi Ueda Tomoki Doue Masahisa Onoguchi Kazuhiro Shiba Akira Odani 《PloS one》2013,8(12)
99mTc-HYNIC-annexin A5 can be considered as a benchmark in the field of apoptosis imaging. However, 99mTc-HYNIC-annexin A5 has characteristics of high uptake and long retention in non-target tissues such as kidney and liver. To minimize this problem, we developed a novel 99mTc-labeled annexin A5 using a bis(hydroxamamide) derivative [C3(BHam)2] as a bifunctional chelating agent, and evaluated its usefulness as an imaging agent for detecting apoptosis. The amino group of C3(BHam)2 was converted to a maleimide group, and was coupled to thiol groups of annexin A5 pretreated with 2-iminothiolane. 99mTc labeling was performed by a ligand exchange reaction with 99mTc-glucoheptonate. Biodistribution experiments for both 99mTc-C3(BHam)2-annexin A5 and 99mTc-HYNIC-annexin A5 were performed in normal mice. In addition, in tumor-bearing mice, the relationship between the therapeutic effects of chemotherapy (5-FU) and the tumor accumulation of 99mTc-C3(BHam)2-annexin A5 just after the first treatment of 5-FU was evaluated. 99mTc-C3(BHam)2-annexin A5 was prepared with a radiochemical purity of over 95%. In biodistribution experiments, 99mTc-C3(BHam)2-annexin A5 had a much lower kidney accumulation of radioactivity than 99mTc-HYNIC-annexin A5. In the organs for metabolism, such as liver and kidney, radioactivity after the injection of 99mTc-HYNIC-annexin A5 was residual for a long time. On the other hand, radioactivity after the injection of 99mTc-C3(BHam)2-annexin A5 gradually decreased. In therapeutic experiments, tumor growth in the mice treated with 5-FU was significantly inhibited. Accumulation of 99mTc-C3(BHam)2-annexin A5 in tumors significantly increased after 5-FU treatment. The accumulation of radioactivity in tumor correlated positively with the counts of TUNEL-positive cells. These findings suggest that 99mTc-C3(BHam)2-annexin A5 may contribute to the efficient detection of apoptotic tumor response after chemotherapy. 相似文献
5.
A molecular basis for the inhibition of brain protein phosphatase 2A (PP2A) activity by oxidative stress was examined in a
high-speed supernatant (HSS) fraction from rat cerebral cortex. PP2A activity was subject to substantial disulfide reducing
agent-reversible inhibition in the HSS fraction. Results of gel electrophoresis support the conclusions that inhibition of
PP2A activity was associated with the both the disulfide cross-linking of the catalytic subunit (PP2AC) of the enzyme to other brain proteins and with the formation of an apparent novel intramolecular disulfide bond in PP2AC. Additional findings that the vicinal dithiol cross-linking reagent phenylarsine oxide (PAO) produced a potent dithiothreitol-reversible
inhibition of PP2A activity suggest that the cross-linking of PP2AC vicinal thiols to form an intramolecular disulfide bond may be sufficient to inhibit PP2A activity under oxidative stress.
We propose that the dithiol–disulfide equilibrium of a vicinal thiol pair of PP2AC may confer redox sensitivity on cellular PP2A. 相似文献
6.
Margaret R. Cunningham Shaista P. Nisar Alexandra E. Cooke Elizabeth D. Emery Stuart J. Mundell 《Traffic (Copenhagen, Denmark)》2013,14(5):585-598
P2Y12 receptor internalization and recycling play an essential role in ADP‐induced platelet activation. Recently, we identified a patient with a mild bleeding disorder carrying a heterozygous mutation of P2Y12 (P341A) whose P2Y12 receptor recycling was significantly compromised. Using human cell line models, we identified key proteins regulating wild‐type (WT) P2Y12 recycling and investigated P2Y12‐P341A receptor traffic. Treatment with ADP resulted in delayed Rab5‐dependent internalization of P341A when compared with WT P2Y12. While WT P2Y12 rapidly recycled back to the membrane via Rab4 and Rab11 recycling pathways, limited P341A recycling was observed, which relied upon Rab11 activity. Although minimal receptor degradation was evident, P341A was localized in Rab7‐positive endosomes with considerable agonist‐dependent accumulation in the trans‐Golgi network (TGN). Rab7 activity is known to facilitate recruitment of retromer complex proteins to endosomes to transport cargo to the TGN. Here, we identified that P341A colocalized with Vps26; depletion of which blocked limited recycling and promoted receptor degradation. This study has identified key points of divergence in the endocytic traffic of P341A versus WT‐P2Y12. Given that these pathways are retained in human platelets, this research helps define the molecular mechanisms regulating P2Y12 receptor traffic and explain the compromised receptor function in the platelets of the P2Y12‐P341A‐expressing patient. 相似文献
7.
Nur Syafiqah Abdul Ghani Roghayeh Abedi Karjiban Mahiran Basri Nur Hana Faujan Wui Zhuan Lim 《International journal of peptide research and therapeutics》2017,23(3):393-407
Alzheimer’s disease (AD) is a neurodegenerative disorder caused by overproduction and accumulation of amyloid beta-peptide (Aβ). The hallmarks associated with this AD are the presence of Aβ plaques between the nerve cell in the brain which leading to synaptic loss in memory. The amyloid plaques contain of transition metals like zinc, copper and iron. In a healthy brain, the metal ions are present in balance concentration. High concentrations of Zn are normally released during neurotransmission process. The release of Zn might cause the aggregation of Aβ leading to AD. Amyloid-β1–42 is the main type of Aβ in amyloid plaque. There still have limited explanation on how Aβ1–42 interaction with Zn metal, as well as the effect of Zn metal on the Aβ structure in different solvents in atomic detail. Therefore, we investigated the structural changes of Aβ1–42 in water (Aβ-H2O) and the mixed hexafluoroisopropanol (HFIP) with water (Aβ-HFIP/H2O). The mixed solvent consisted of hexafluoroisopropanol (HFIP) and water was used with the ratio of HFIP:H2O (80:20). The effect of zinc ion was also examined for the interaction of Aβ peptide with zinc in water (Aβ-Zn-H2O) and mixed solvent (Aβ-Zn-HFIP/H2O) using all atom level molecular dynamics (MD) calculations for 1 μs. We found that Aβ-Zn-HFIP/H2O contained more α-helix compared to Aβ-HFIP/H2O while Aβ-H2O and Aβ-Zn-H2O produced well-dissolved structure and they contained more β-sheets. β-turns are possible to bind with the receptor proteins and may induce the aggregation process in AD. Thus, Aβ-H2O and Aβ-Zn-H2O have higher possibility leading to AD compared to Aβ-Zn-HFIP/H2O and Aβ-HFIP/H2O models. 相似文献
8.
9.
Wendy A. Wallner Michael J. P. Lawman Michael D. P. Boyle 《Applied microbiology and biotechnology》1987,27(2):168-173
Summary The interaction of bovine immunoglobulins with staphylococcal Protein A and a group C streptococcal bacterial Fc receptor (FcRc) were compared. The isolated group C streptococcal receptor was reactive with both bovine IgG1 and IgG2. The reactivity of the streptococcal FcRc with IgG2 was approximately 40 fold greater than that observed with IgG1. By contrast, protein A reacted only poorly with bovine IgG2 and no detectable reactivity was observed with IgG1. A two stage competitive binding assay to measure bovine IgG in serum and secretions using 125I-labeled protein A as tracer was developed. This assay was found to be sensitive and reproducible and was used to measure serum IgG levels in cattle of differing ages and breeds. 相似文献
10.
Hager Jouili Houda Bouazizi Michel Rossignol Gisle Borderies Elisabeth Jamet Ezzeddine El Ferjani 《Plant Physiology and Biochemistry》2008,46(8-9):760-767
Treatment of 14-day-old sunflower seedlings with a toxic amount of copper (50 μM of CuSO4) during 5 days caused significant increase in peroxidase activity in roots. Qualitative analysis of soluble proteins using native anionic PAGE followed by detection of peroxidase activity with guaïacol as electron donor in the presence of H2O2 revealed five stimulated peroxidases, named A1, A2, A3, A4, and A5. These peroxidases had differential behavior during the period of treatment. A1, A2, A3 and A4 were stimulated in the first period of stress, but rapidly suppressed at 72 h. A5 showed a progressive stimulation which was even increased at 120 h. A1 was partially purified, identified using liquid chromatography coupled to mass spectrometry (LC-MS/MS), and characterized. Effects of pH and temperature on its activity were determined with guaïacol as electron donor. Optima were obtained at pH 8 and at 40 °C. Analysis of substrate specificity showed that A1 was active on coniferyl alcohol but not on IAA. Enzymatic activity was inhibited by a high concentration of H2O2. 相似文献
11.
Homotropic cooperativity of 1-alkoxy-4-nitrobenzene substrates and also their heterotropic cooperative binding interactions with the iron ligand 1,4-phenylene diisocyanide (Ph(NC)2) had been demonstrated previously with rabbit cytochrome P450 (P450) 1A2 [G.P. Miller, F.P. Guengerich, Biochemistry 40 (2001) 7262-7272]. Multiphasic kinetics were observed for the binding of Ph(NC)2 to both ferric and ferrous P450 1A2, including relatively slow steps. Ph(NC)2 induced an apparently rapid change in the circular dichroism spectrum, consistent with a structural change, but had no effect on tryptophan fluorescence. Ph(NC)2 binds the P450 iron in both the ferric and ferrous forms; ferric P450 1A2 was reduced rapidly in the absence of added ligands, and the rate was attenuated when Ph(NC)2 was bound. No oxidation products of Ph(NC)2 were detected. Docking studies with a rabbit P450 1A2 homology model based on the published structure of a human P450 1A2·α-naphthoflavone (αNF) complex indicated adequate room for a complex with either two 1-isopropoxy-4-nitrobenzene molecules or a combination of one 1-isopropoxy-4-nitrobenzene and one Ph(NC)2; in the case of αNF no space for an extra ligand was available. The patterns of homotropic cooperativity seen with 1-alkoxy-4-nitrobenzenes (biphasic plots of v vs. S) differ from those seen with polycyclic hydrocarbons (positive cooperativity), suggesting that only with the latter does the ligand interaction produce improved catalysis. Consistent with this view, Ph(NC)2 inhibited the oxidation of 1-isopropoxy-4-nitrobenzene and other substrates. 相似文献
12.
Jun-O Jin Valeria V. Shastina Sung-Won Shin Joo-In Park Sergey A. Avilov Valentin A. Stonik Jong-Young Kwak 《FEBS letters》2009,583(4):697-34
Frondoside A is a pentaoside having an acetyl moiety at the aglycon ring and xylose as a third monosaccharide residue. Cucumarioside A2-2 is a pentaoside having glucose as a third monosaccahride unit. We compared the effects of frondoside A and A2-2 for cell death-inducing capability with close attention paid to structure-activity relationships. Both frondoside A and A2-2 strongly induced apoptosis of leukemic cells. Frondoside A-induced apoptosis was more potent and rapid than A2-2-induced apoptosis. A2-2-induced but not frondoside A-induced apoptosis was caspase-dependent. This suggests that holothurians may induce apoptosis of leukemic cells caspase-dependently or -independently, depending on the holothurian structure. 相似文献
13.
B Strulovici Y Weinstein U Zor 《Biochemical and biophysical research communications》1981,103(2):638-646
Prolonged exposure (> 6 h) of cultured granulosa cells to Prostaglandin E2 (PGE2; 1 μg/ml) led to a near-total loss of the cyclic AMP response to subsequent addition of fresh hormone. Pre-treatment of the cells with concanavalin A (ConA; 2.0 μg/ml) for 1 h blocked the desensitizing action of PGE2, so that the decline in the response was reduced by 60% with the hormone at high concentration (1.0 μg/ml); a full response was preserved at submaximal concentration of PGE2 (0.1 – 0.3μg/ml). Other lectins (succinyl Con a, peanut agglutinin and, to a lesser extent, phytohemagglutinin and wheat germ agglutinin) had a stabilizing effect similar to that of Con A. Addition of alpha-methyl-mannoside either with Con A or various times following the addition of Con A to the cells prevented the protective effect of Con A. Concomitant treatment with colchicine or cytochalasin B abolished the ability of Con A to prevent PGE2-induced desensitization. 相似文献
14.
During growth of Acetobacterium woodii on fructose, glucose or lactate in a medium containing less than 0.04% bicarbonate, molecular hydrogen was evolved up to 0.1 mol per mol of substrate. Under an H2-atmosphere growth of A. woodii with organic substrates was completely inhibited whereas under an H2/CO2-atmosphere rapid growth occurred. Under these conditions H2+CO2 and the organic substrate were utilized simultaneously indicating that A. woodii was able to grow mixotrophically.
Clostridium aceticum differed from A. woodii in that H2 was only evolved in the stationary phase, that the inhibition by H2 was observed at pH 8.5 but not at pH 7.5, anf that in the presence of fructose and H2+CO2 only fructose was utilized.The hydrogenase activity of fructose-grown cells of C. aceticum amounted to only 12% of that of H2+CO2-grown cells. With A. woodii a corresponding decrease of the activity of this enzyme was not observed. 相似文献
15.
Verónica Sáez-Jiménez Sandra Acebes Victor Guallar Angel T. Martínez Francisco J. Ruiz-Due?as 《PloS one》2015,10(4)
Ligninolytic peroxidases are enzymes of biotechnological interest due to their ability to oxidize high redox potential aromatic compounds, including the recalcitrant lignin polymer. However, different obstacles prevent their use in industrial and environmental applications, including low stability towards their natural oxidizing-substrate H2O2. In this work, versatile peroxidase was taken as a model ligninolytic peroxidase, its oxidative inactivation by H2O2 was studied and different strategies were evaluated with the aim of improving H2O2 stability. Oxidation of the methionine residues was produced during enzyme inactivation by H2O2 excess. Substitution of these residues, located near the heme cofactor and the catalytic tryptophan, rendered a variant with a 7.8-fold decreased oxidative inactivation rate. A second strategy consisted in mutating two residues (Thr45 and Ile103) near the catalytic distal histidine with the aim of modifying the reactivity of the enzyme with H2O2. The T45A/I103T variant showed a 2.9-fold slower reaction rate with H2O2 and 2.8-fold enhanced oxidative stability. Finally, both strategies were combined in the T45A/I103T/M152F/M262F/M265L variant, whose stability in the presence of H2O2 was improved 11.7-fold. This variant showed an increased half-life, over 30 min compared with 3.4 min of the native enzyme, under an excess of 2000 equivalents of H2O2. Interestingly, the stability improvement achieved was related with slower formation, subsequent stabilization and slower bleaching of the enzyme Compound III, a peroxidase intermediate that is not part of the catalytic cycle and leads to the inactivation of the enzyme. 相似文献
16.
A method for the preparation of a highly purified sample of rabbit blood monocytes is described. The metabolism of arachidonic acid (AA) in these cells was studied. Mononuclear cells were prepared by centrifugation on Ficoll-Paque gradients and the monocytes were obtained by further centrifugation and adherence onto plastic culture dishes. These procedures provided a preparation which contained 95% monocytes (non-specific esterase positive). Incubation of [1-14C]-AA with these cells produced four major metabolites which were separated by TLC; these corresponded to prostaglandin (PG) D2, thromboxane (TX) B2, 12-hydroxyheptadecatrienoic acid (HHT) and 12-/15- hydroxyeicosatetraenoic acid (HETE). A minor product which co-migrated with PGE2 was also detected but neither 6-keto-PGF1α nor PGF2α were detected. Also, there was no evidence of the formation of 5-lipoxygenase products (5-HETE and LTB4) by rabbit monocytes with or without calcium-ionophore A23187-stimulation. The production of PGD2, TXB2 and PGE2 was further confirmed by analyzing [3H]-AA metabolites using high-performance liquid chromatography (HPLC) with tritiated standards as references. The biosynthesis of these compounds from endogenous substrate in A23187-stimulated monocytes was confirmed by specific radioimmunoassays with or without prior HPLC separation. The synthesis of immunoreactive LTB4 and LTC4 by A23187-stimulated cells was also monitored and found to be relatively low. The synthesis of PGD2, TXB2 and PGE2 from both exogenous and endogenous substrate was suppressed by treatment of the monocytes with indomethacin (10−6 M). 相似文献
17.
《Peptides》2016
Neurite outgrowth is an important process in neural regeneration and plasticity, especially after neural injury, and recent evidence indicates that several Gαi/o protein-coupled receptors play an important role in neurite outgrowth. The neuropeptide (NP)FF system contains two Gαi/o protein-coupled receptors, NPFF1 and NPFF2 receptors, which are mainly distributed in the central nervous system. The aim of the present study was to determine whether the NPFF system is involved in neurite outgrowth in Neuro 2A cells. We showed that Neuro 2A cells endogenously expressed NPFF2 receptor, and the NPFF2 receptor agonist dNPA inhibited cyclic adenosine monophosphate (cAMP) production stimulated by forskolin in Neuro 2A cells. We also demonstrated that NPFF and dNPA dose-dependently induced neurite outgrowth in Neuro 2A cells, which was completely abolished by the NPFF receptor antagonist RF9. Pretreatment with mitogen-activated protein kinase inhibitors PD98059 and U0126 decreased dNPA-induced neurite outgrowth. In addition, dNPA increased phosphorylation of extracellular signal-regulated kinase (ERK) in Neuro 2A cells, which was completely antagonized by pretreatment with U0126. Our results suggest that activation of NPFF2 receptor stimulates neurite outgrowth in Neuro 2A cells through activation of the ERK signaling pathway. Moreover, NPFF2 receptor may be a potential therapeutic target for neural injury and degeneration in the future. 相似文献
18.
Detached cowpea nodules that contained a nitrous oxide reductase-positive (Nor+) rhizobium strain (8A55) and a nitrous oxide reductase-negative (Nor−) rhizobium strain (32H1) were incubated with 1% 15N2O (95 atom% 15N) in the following three atmospheres: (i) aerobic with C2H2 (10%), (ii) aerobic without C2H2, and (iii) anaerobic (argon atmosphere) without C2H2. The greatest production of 15N2 occurred anaerobically with 8A55, yet very little was formed with 32H1. Although acetylene reduction activity was slightly higher with 32H1, about 10 times more 15N2 was produced aerobically by 8A55 than by 32H1 in the absence of acetylene. The major reductive pathway of N2O reduction by denitrifying rhizobium strain 8A55 is by nitrous oxide reductase rather than nitrogenase. 相似文献
19.
Alan S. Bowman Jack W. Dillwith Robin D. Madden John R. Sauer 《Archives of insect biochemistry and physiology》1995,29(3):309-327
An important regulatory step for prostaglandin synthesis is the availability of the precursor, free arachidonic acid (AA). In isolated salivary glands of the lone star tick, Amblyomma americanum (L.), the level of free AA appears to depend on higher phospholipase A2 (PLA2) activity rather than decreased rates of re-esterification by lysophosphatide acyl transferase (LAT). This conclusion is supported by experiments where inhibition of LAT with merthiolate was without effect, while the calcium ionophore A23187, a PLA2 stimulant, increased levels of free AA. The PLA2 activity in A. americanum was reduced by the substrate analog, PLA2 inhibitor, oleyloxyethyl phosphorylcholine in a dose-dependent manner, but was insensitive to the other mammalian PLA2 inhibitors mepacrine (20μM), aristolochic acid (45μM), and dexamethasone (50μM). No substrate preference was observed for the functional group of the phospholipid, with phosphatidylcholine and phosphatidylethanolamine being equal sources of AA in A23187-stimulated glands. Compared to phospholipids containing other fatty acids, only arachidonyl-phospholipid (arachidonyl-PL) was significantly hydrolyzed by PLA2 activity in A23187-stimulated glands. Dopamine was as effective as A23187 as a stimulant of PLA2 activity in isolated glands, but this effect was abolished in the presence of the calcium channel blocking agent verapamil. It is concluded that free AA levels in tick salivary glands are increased through activation of a Type IV-like PLA2 following an increase of intracellular calcium caused by the opening of voltage-dependent calcium channels due to dopamine stimulation. © 1995 Wiley-Liss, Inc. 相似文献
20.
《Process Biochemistry》2007,42(4):599-605
A novel process was developed and demonstrated that a coupled syntrophic acetogenesis with homoacetogenesis reaction was able to enhance acetate production from high strength synthetic wastewater containing glucose by mixed cultures. A coupling system was constructed with two bioreactors which were connected via a silicon rubber pipe. The first reactor (bioreactor A) was for syntrophic acetogenesis, in which glucose was converted to volatile fatty acids consisting primarily of acetate. The second (bioreactor H) was for homoacetogenesis in which CO2 and H2 from bioreactor A were converted to acetate. Acetate yield in the coupling system was 87% higher than that in control 1, in which the homoacetogenesis did not occur. Also, acetate yield in the coupling system was 52% higher than that in control 2, which consisted of only bioreactor A and the gas in the headspace was released manually once a day. Enhancement of acetate production was contributed principally to relieve of the products (H2 and CO2) inhibition to syntrophic acetogenesis in bioreactor A, in which the degradation of glucose and the conversion of ethanol were enhanced. This coupling process provides a strategy for increasing acetate production and the degradation rate of the substrate. 相似文献