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1.
Cecilia PC Soh Alastair SR Donald James Feeney Walter TJ Morgan Winifred M Watkins 《Glycoconjugate journal》1989,6(3):319-332
The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and1H-500 MHz NMR spectroscopy. In Sda serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity. 相似文献
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Muscarinic Acetylcholine Receptors in Torpedo Electric Organ: Effect of Guanine Nucleotides 总被引:2,自引:2,他引:0
Abstract: The effect of guanine nucleotides on the binding properties of presynaptic muscarinic receptors has been studied in a membrane preparation from the electric organ of Torpedo marmorata by measuring the competitive displacement of the radiolabelled antagonist, [3 H]quinuclidinyl benzilate, by nonradioactive muscarinic ligands. The binding of the antagonists, atropine, scopolamine and pirenzepine was to a single class of sites [slope factors (pseudo Hill coefficients) close to 1] and was unaffected by 0.1 m M GTP. The binding of the N -methylated antagonists, N -methylatropine and N -methyl-scopolamine was more complex (slope factors <1) but also insensitive ( N- methylatropine) to 0.1 m M GTP. Agonist binding was complex and could be resolved into two binding sites with relatively high and low affinities. The proportion of high-affinity sites varied with the nature of the agonist (15–80%). Agonist binding was depressed by 0.1 m M GTP, and the order of sensitivity was oxotremorine-M > carbamoylcholine > muscarine > acetylcholine > arecoline > oxotremorine. The binding of pilocarpine, a partial agonist, was unaffected by GTP. With carbamoylcholine as a test ligand the GTP effect on agonist binding was half-maximal at 12 μM. GDP and guanylylimidodiphosphate produced comparable inhibition of carbamoylcholine binding, but GMP and cyclic GMP were ineffective, as were various adenine nucleotides. Analysis of agonist binding in terms of a two-site model indicates that the predominant effect of guanine nucleotides is to reduce the number of sites of higher affinity. 相似文献
3.
Transformation of peripheral blood lymphocytes after exposure to connective tissue antigens was measured in patients with adult (n = 35) and juvenile rheumatoid arthritis (n = 34), osteoarthritis (n = 21), ankylosing spondylitis (n = 15), and systemic lupus erythematosus (n = 26) and in control subjects (n = 36). The connective tissue antigens included homologous cartilage-type proteoglycan, cyanogen bromide-derived peptides of type I, II, and III collagens, and type I and II helical collagens. Lymphocyte transformation was not detected in the osteoarthritic and control groups, with one exception. Sensitization to at least one connective tissue antigen was detected in approximately one-third of the rheumatoid arthritic and lupus patients and in one-quarter of the juvenile rheumatoid patients. In ankylosing spondylitis, positive responses occurred to proteoglycan in 20% of patients tested but never to collagens or peptides. Sensitivity to proteoglycan was detected only in ankylosing spondylitis except for one patient with juvenile rheumatoid arthritis. In patients with systemic lupus erythematosus and both forms of rheumatoid arthritis, lymphocyte transformation was usually more frequently detected to peptides than to the helical collagens. In adult rheumatoid arthritis, type II peptides elicited an elevated number of responses (14%) as did type I (9%) and III (8%) peptides to lesser degrees. Responses to type I (4%) and II (4%) helical collagens were infrequent. Rheumatoid arthritic patients usually exhibited sensitivity to only one antigen and lymphocyte transformation was often detected when the arthritis was improving. In juvenile rheumatoid arthritis, lymphocyte transformation was detected to peptides of type I (16%), II (9%), and III (29%) collagens and to helical type I (12%) and II (8%) collagens. In systemic lupus erythematosus, sensitization was detected to peptides of type I (13%), II (20%), and III (14%) collagens and to helical type I collagen (18%) but not type II collagen. Simultaneous sensitivity to several antigens often occurred in both systemic lupus erythematosus and juvenile rheumatoid arthritis. Examination of individual patients in all three rheumatic disease groups revealed that immune sensitivity developed to collagen peptides rather than to the helical molecules, particularly in the case of type II collagen. Thus, some patients with inflammatory arthritis exhibit immune responses to connective tissue components which are, as a group, characteristic for each type of arthritis. These responses, which were not obviously associated with disease activity, may develop as a result of inflammation or trauma which destroys connective tissue and exposes molecules, in either a native or degraded state, to cells of the immune system. Expression of sensitivity to these tissue antigens may contribute to the chronicity of the inflammatory arthritides. 相似文献
4.
E. L. Rech T. J. Golds T. Husnain M. H. Vainstein B. Jones N. Hammatt B. J. Mulligan M. R. Davey 《Plant cell reports》1989,8(1):33-36
Seedling hypocotyl explants ofGlycine canescens were inoculated withAgrobacterium rhizogenes carrying a chimaeric NPTII gene cointegrated into the TL-DNA of pRiA4. Transformed roots produced shoots on B5 based medium with 10.0 mgl–1 BAP, 0.05 mgl–1 IBA and 50 gml–1 kanamycin. Cultured roots and regenerated plants expressed NPTII enzyme activity which was correlated with the presence of Ri TL-DNA and the structural sequence of the NPTII gene.Abbreviations BAP
6-benzylaminopurine
- BSA
bovine serum albumin
- DTT
dithiothreitol
- EDTA
ethylenediaminetetraacetic acid
- IBA
indole-butyric acid
- PAGE
polyacrylamide gel electrophoresis
- NPTII
neomycin phosphotransferase II
- PMSF
phenylmethylsulphonyl fluoride
- SDS
sodium dodecylsulphate 相似文献
5.
Immature zygotic embryos from spring barley cv. Dissa were used to induce somatic embryogenenesis. Up to 158 germinated somatic embryos could be recovered per plated zygotic embryo. Critical factors for obtaining a high yield of regenerants were the size of the explant, the level of 2,4-D used for callus induction and the careful division of callus at each subculture. Use of microsections of immature embryos as explants revealed a pronounced gradient of callus formation and embryogenic response across the scutellum. Sections from the scutellar tissue at the coleoptilar end of the embryo gave the most callus and were highly embryogenic. The regeneration response of sectioned explants was comparable to that recovered from intact embryos of similar size. 相似文献
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Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport 总被引:11,自引:9,他引:2 下载免费PDF全文
Catecholamines induce net salt and water movements in duck red cells incubated in isotonic solutions. The rate of this response is approximately three times greater than a comparable effect observed in 400 mosmol hypertonic solutions in the absence of hormone (W.F. Schmidt and T. J. McManus. 1977 a.J. Gen. Physiol. 70:59-79. Otherwise, these two systems share a great many similarities. In both cases, net water and salt movements have a marked dependence on external cation concentrations, are sensitive to furosemide and insensitive to ouabain, and allow the substitution of rubidium for external potassium. In the presence of ouabain, but the absence of external potassium (or rubidium), a furosemide-sensitive net extrusion of sodium against a large electrochemical gradient can be demonstrated. When norepinephrine-treated cells are incubated with ouabain and sufficient external sodium, the furosemide-sensitive, unidirectional influxes of both sodium and rubidium are half- maximally saturated at similar rubidium concentrations; with saturating external rubidium, the same fluxes are half-maximal at comparable levels of external sodium. In the absence of sodium, a catecholamine-stimulated, furosemide-sensitive influx of rubidium persists. In the absence of rubidium, a similar but smaller component of sodium influx can be seen. We interpret these results in terms of a cotransport model for sodium plus potassium which is activated by hypertonicity or norepinephrine. When either ion is absent from the incubation medium, the system promotes an exchange-diffusion type of movement of the co-ion into the cells. In the absence of external potassium, net movement of potassium out of the cell leads to a coupled extrusion of sodium against its electrochemical gradient. 相似文献
8.
Sara Rosati Ewald TJ van den Bremer Janine Schuurman Paul WHI Parren Johannis P Kamerling Albert JR Heck 《MABS-AUSTIN》2013,5(6):917-924
Here, we describe a fast, easy-to-use, and sensitive method to profile in-depth structural micro-heterogeneity, including intricate N-glycosylation profiles, of monoclonal antibodies at the native intact protein level by means of mass spectrometry using a recently introduced modified Orbitrap Exactive Plus mass spectrometer. We demonstrate the versatility of our method to probe structural micro-heterogeneity by describing the analysis of three types of molecules: (1) a non-covalently bound IgG4 hinge deleted full-antibody in equilibrium with its half-antibody, (2) IgG4 mutants exhibiting highly complex glycosylation profiles, and (3) antibody-drug conjugates. Using the modified instrument, we obtain baseline separation and accurate mass determination of all different proteoforms that may be induced, for example, by glycosylation, drug loading and partial peptide backbone-truncation. We show that our method can handle highly complex glycosylation profiles, identifying more than 20 different glycoforms per monoclonal antibody preparation and more than 30 proteoforms on a single highly purified antibody. In analyzing antibody-drug conjugates, our method also easily identifies and quantifies more than 15 structurally different proteoforms that may result from the collective differences in drug loading and glycosylation. The method presented here will aid in the comprehensive analytical and functional characterization of protein micro-heterogeneity, which is crucial for successful development and manufacturing of therapeutic antibodies 相似文献
9.
The diageotropica mutation alters auxin induction of a subset of the Aux/IAA gene family in tomato 总被引:5,自引:0,他引:5
The diageotropica (dgt) mutation has been proposed to affect either auxin perception or responsiveness in tomato plants. It has previously been demonstrated that the expression of one member of the Aux/IAA family of auxin-regulated genes is reduced in dgt plants. Here, we report the cloning of ten new members of the tomato Aux/IAA family by PCR amplification based on conserved protein domains. All of the gene family members except one (LeIAA7) are expressed in etiolated tomato seedlings, although they demonstrate tissue specificity (e.g. increased expression in hypocotyls vs. roots) within the seedling. The wild-type auxin-response characteristics of the expression of these tomato LeIAA genes are similar to those previously described for Aux/IAA family members in Arabidopsis. In dgt seedlings, auxin stimulation of gene expression was reduced in only a subset of LeIAA genes (LeIAA5, 8, 10, and 11), with the greatest reduction associated with those genes with the strongest wild-type response to auxin. The remaining LeIAA genes tested exhibited essentially the same induction levels in response to the hormone in both dgt and wild-type hypocotyls. These results confirm that dgt plants can perceive auxin and suggest that a specific step in early auxin signal transduction is disrupted by the dgt mutation. 相似文献
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