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221.
One- and two-dimensional NMR studies on the conformation of DNA containing the oligo(dA)oligo(dT) tract. 总被引:8,自引:6,他引:2 下载免费PDF全文
M Katahira H Sugeta Y Kyogoku S Fujii R Fujisawa K Tomita 《Nucleic acids research》1988,16(17):8619-8632
The resonances of the imino protons and all of the non-exchangeable protons (except for H5'/H5') of d(CGCAAAAAAGCG)d(CGCTTTTTTGCG) have been assigned by means of one- and two-dimensional NMR spectroscopies. Qualitative analyses showed that the overall structure is of the B-form, but local conformational deviations exist. The NOEs between the imino protons of thymines and H2 of adenines suggest that the A-T base pairs are propeller-twisted to almost the same degree as in crystals. A remarkable chemical shift of H1' was observed for the residue located just before the oligo(dA)oligo(dT) tract, suggesting the presence of conformational discontinuity at the junctions between the oligo(dA)oligo(dT) tract and the other portions. Analyses of cross peaks in NOESY spectra between H2 of adenines and H1' of the 3'-neighbouring residues on the complementary strand revealed that the minor groove of the oligo(dA)oligo(dT) tract is narrow and compressed gradually, from 5' to 3', along the tract. 相似文献
222.
Selective inhibition of high- but not low-affinity interleukin 2 binding by lectins and anti-interleukin 2 receptor alpha antibody 总被引:1,自引:0,他引:1
The present study demonstrated that various reagents can specifically reduce the affinity of high-affinity interleukin 2 receptor (IL-2R) but not that of low-affinity IL-2R. They included lectins such as wheat germ agglutinin (WGA), concanavalin A and phytohemagglutinin, and a chemical cross-linker, glutaraldehyde, in addition to anti-IL-2R monoclonal antibodies, HIEI and H-47. The affinity of the high-affinity IL-2R was reduced when the cells were treated with WGA or H-47 before, but not after, addition of 125I-labeled interleukin 2 (IL-2). Their inhibitory effects were also demonstrated by the chemical cross-linking method. On treatment with the reagents, the IL-2 binding to both IL-2R alpha and beta chains was inhibited and these inhibitory effects were seen only when the reagents were added before IL-2 addition, like their high-affinity reducing effects. These results support a supposition that the high affinity IL-2R is generated by assembly of the alpha and beta chains, and suggest that the IL-2 binding to IL-2R alpha and beta chains could induce stable constitution of the high-affinity state of IL-2R, but these affinity modulating reagents could perturb the optimum association between alpha and beta chains to generate the high-affinity IL-2R. 相似文献
223.
The semen of six different bulls was used to examine the effects of treatment with caffeine or caffeine plus Ca-ionophre on in vitro fertilization, cleavage and development into morulae of in vitro matured bovine oocytes. In vitro fertilization results (formation of both pronuclei, cleavage and development to >/= four-cell stage were significantly (P<0.01) higher using caffeine plus Ca-ionophre than those using only caffeine. The rates of fertilization and first cleavage were only slightly variable among the bulls. However, the present data showed significant variability in formation of both pronuclei (36 to 75%) of fertilized ova and development to the >/=4cell stage (39 to 71%) by different bulls. Development into morulae of ova recovered from the rabbit oviduct did not show any significant differences in relation to sperm treatments or individual bulls. 相似文献
224.
The anomeric preference in the influx and efflux of D-glucose across the human erythrocyte membrane was studied. beta-D-Glucose was transported 1.5 times faster than alpha-D-glucose into the cells, when washed cells were incubated at 20 degrees C in medium containing either alpha- or beta-D-glucose (100 mM). On the other hand, no difference between half-times of efflux of the two anomers was distinguishable. The result demonstrates the presence of influx-efflux asymmetry in anomeric preference in D-glucose transport across the human erythrocyte membrane, and is consistent with the view (Barnett et al., Biochem. J. 145, 417-429, 1975) that the C-1 hydroxyl group of D-glucose interacts with the D-glucose transport protein only in the influx, but not in the efflux. 相似文献
225.
Characterization of Microtubule-Associated Protein 2 from Mouse Brain and Its Localization in the Cerebellar Cortex 总被引:3,自引:2,他引:1
Michio Niinobe Nobuaki Maeda Hidetoshi Ino Katsuhiko Mikoshiba 《Journal of neurochemistry》1988,51(4):1132-1139
Microtubule-associated protein (MAP) 2 was purified from the microtubule fraction of mouse brain by heat treatment and BioGel A-5m gel filtration. The purified preparation showed a single protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis using both a gradient gel (3.75-12.5%) and a low-percentage gel (5%), a finding indicating that MAP2B was absent under the conditions used. Amino acid analysis revealed that mouse MAP2 was an acidic protein with an isoelectric point (pI 4.5) and amino acid composition similar to those of porcine brain MAP2. Immunoblot analysis indicated that the antigens that reacted with MAP2 antiserum were present in large quantities in mouse brain. However, we also found a weak reaction in various tissues other than brain, and the major antigens involved were recognized to be common molecular species with the same molecular mass, 162 and 170 kilodaltons. Using antiserum against mouse brain MAP2, the developmental localization patterns of MAP2 in the mouse cerebellar cortex were studied by immunohistochemistry. MAP2 was mainly localized in the neuronal cells throughout development, with the expression in Purkinje cell dendrites being especially remarkable in the growth of arborization from postnatal day 3 to day 20. At the mature stage, the reaction was strong in the dendritic tree but very weak in the proximal dendrites and cell bodies. 相似文献
226.
Regulation of antibody production by helper T cell clones in experimental autoimmune myasthenia gravis 总被引:4,自引:0,他引:4
Ten acetylcholine receptor (AChR)-specific T cell clones from Lewis rats were studied. These clones had various AChR subunit and peptide specificities, and proliferated in response to antigen on appropriate APC. All the T cell clones were CD4+CD8- and OX22-, helped anti-AChR antibody production by AChR-primed lymph node B cells, and could secrete IL-2. However, several lines of evidence suggested that IL-2 was not the lymphokine that mediated T cell help. B cells primed with native AChR and then exposed in culture to very low concentrations of native AChR effectively presented the Ag to the T cell lines, presumably due to uptake via Ag receptors, but primed B cells were no more effective than were non-specific APC at presenting a synthetic AChR peptide which is recognized by AChR-specific T cells but not by AChR-specific B cells. Increasing AChR doses produced an antibody production response that was bell shaped and low doses stimulated, whereas higher AChR concentrations suppressed the antibody production response. Evidence suggested that AChR exerted its inhibitory effect through the T cells, but not via IL-2. 相似文献
227.
A glycoprotein (GP57) was purified by ion-exchange and hydroxylapatite column chromatography from the 70%-ethanol precipitate of culture medium of non-embryogenic carrot cells (Daucus carota L.) grown with 2,4-dichlorophen-oxyacetic acid (2,4-D). Its apparent molecular mass (M
r) was estimated to be 57000 by sodium dodecylsulfate-polyacrylamide gel electrophoresis and 50000 by gel filtration. GP57 contained 14% (w/w) carbohydrate; the M
r of the peptide portion was estimated to be 55000 after deglycosylation by trifluoromethanesulfonic acid. GP57 is composed of two polypeptides with the same Mr and with very similar amino-acid composition but different pI values, 8.8 and 9.5. Both are rich in aspartic acid, serine and threonine, and may possess N-linked oligosaccharide chains, including fucose and xylose. A monoclonal antibody (MAb) against the purified GP57 reacted with both the pI 8.8 and the 9.5 components, as well as the deglycosylated GP57. Immunoblotting with the MAb indicated that GP57 is synthesized in and released from cultured cells which have been supplied with auxin. In immunocytochemical studies, GP57 was found in the space between the embryo and the endosperm of dry seeds, and its content decreased during germination. GP57 was also found in the endodermis and epidermis of young roots, the periderm of mature taproots, and the epidermis of petioles and young leaves.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- GP57
M
r-57000 glycoprotein
- GP65
M
r-65000 glycoprotein
- MAb
monoclonal antibody
-
M
r
apparent molecular mass
- SDS-PAGE
sodium dodecylsulfate-polyacrylamide gel electrophoresis
- TFMS
trifluoromethanesulfonic acid 相似文献
228.
H Miyazaki T Fujii H Amejima N Mikuriya K Nambu A Kagemoto M Nakao Y Oh-e K Matsumoto Y Matsui 《Biotherapy》1988,1(1):7-18
Disposition of [125I]rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation. After i.v. administration, [125I]rHu-TNF measured by radioactivity and immunoreactivity biphasically decreased in plasma. Tumor level of [125I]rHu-TNF was the maximum at 1 h, then decreased and finally remained essentially constant. After i.t. administration, plasma level reached the maximum at 1 h. Tumor level decreased quickly and then became essentially constant. [125I]rHu-TNF was suggested to be degraded to small fragments in the tumor. Significant distribution of [125I]rHu-TNF was found in the kidney, lung, liver and tumor. Most tissue levels decreased with time in parallel with plasma levels. [125I]rHu-TNF radioactivity was found in proximal convoluted tubules of kidney and in those areas of tumor consisting of degenerating cells with pyknotic nuclei. Urine contained most of administered radioactivity, which being neither immunoreactive nor protein-bound. 相似文献
229.
A Ohtsu K Fujii S Kurozumi 《Prostaglandins, leukotrienes, and essential fatty acids》1988,33(1):35-39
Angiogenic activities of several chemically stable prostacyclin analogs (isocarbacyclins and 7-fluoro prostacyclin) were evaluated by the chick embryo chorioallantoic membrane assay. These compounds showed potent angiogenic activity at very low concentration (0.1 micrograms/egg 1.0 micrograms/egg), whereas naturally occurring prostaglandins such as prostacyclin and PGE1 were almost ineffective up to 1 microgram/egg. Pretreatment of chorioallantoic membranes with dexamethasone or indomethacin inhibited the angiogenic response induced by these chemically stable prostacyclin analogs. These results indicate that these prostacyclin analogs induce the angiogenic response of chick chorioallantoic membranes via a mechanism involving activation of inflammatory cells, as well as through their direct angiogenic activity. 相似文献
230.
Kazuhiro Nakaya 《Ichthyological Research》1988,34(4):431-442
Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length. 相似文献