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31.
A monoclonal antibody that triggers deacylation of an intermediate thrombin-antithrombin III complex
S Asakura M Matsuda N Yoshida S Terukina H Kihara 《The Journal of biological chemistry》1989,264(23):13736-13739
Upon incubation of antithrombin III with thrombin in the presence of a monoclonal antibody recognizing an epitope exposed on the heavy chain part of thrombin-cleaved two-chain antithrombin III, antithrombin III was preferentially cleaved by the enzyme as a substrate, rather than covalently complexed with the enzyme to form an equimolar, stable acyl complex. Once the stable acyl complex was formed between the enzyme and antithrombin III, however, no further liberation of two-chain antithrombin III was observed. Kinetic studies showed that heparin does not affect this reaction, although generation of thrombin-cleaved two-chain antithrombin III is apparently accelerated in accordance with the rate constant for heparin-enhanced thrombin-antithrombin III complex formation. Here we propose the term "switching antibody" for an antibody that triggers deacylation of an intermediate enzyme-inhibitor complex by switching the enzyme-inhibitor reaction from the major pathway of stable acyl complex formation to an alternative pathway of cleavage of the inhibitor as a substrate. 相似文献
32.
Switch circular DNA formed in cytokine-treated mouse splenocytes: evidence for intramolecular DNA deletion in immunoglobulin class switching 总被引:29,自引:0,他引:29
We have characterized circular DNA in mouse splenocytes treated with the mitogen lipopolysaccharide (LPS) and various cytokines, including transforming growth factor beta (TGF-beta) and interleukin 4 (IL-4). Using probes of immunoglobulin heavy chain constant genes (CH), excision products of class switch recombination were identified. The majority of the clones contained the 3' portion of the switch mu (S mu) region and the 5' portion of other switch regions. Some clones contained 3'-S gamma sequences instead of 3'-S mu. This indicates that isotype switching may occur not only from C mu, but also from one of the C gamma genes to other CH genes further down-stream. In the presence of LPS, the cytokine TGF-beta enhanced the detection of 5'-S alpha-positive clones, while the lymphokine IL-4 enhanced 5'-S gamma 1 positives. The data support the notion that TGF-beta and IL-4 can direct isotype-specific class switching. 相似文献
33.
Origin of "fused" glucose-6-phosphate dehydrogenase. 总被引:2,自引:0,他引:2
34.
Y Katagata K Aso M Sato T Yoshida 《Biochemical and biophysical research communications》1992,182(3):1440-1445
To date, the largest keratin peptide(K1, 68 KD) has been absent in cultured human squamous cell carcinomas. Using a low salt aqueous solution, not containing high salt and Triton X-100, as a washing buffer for keratin extraction, followed by two dimensional polyacrylamide gel electrophoresis, immunological techniques and Northern blot analysis, we demonstrated K1 peptide in two kinds of cultured human squamous cell carcinomas. Until now keratin extraction has been done using high salt/Triton X-100 solution during which K1 peptide may be removed together developed an affinity with the buffer. Many investigators may have therefore overlooked K1. 相似文献
35.
Homogeneously purified poly(ADP-ribose) polymerase (PARP) specifically stimulated the activity of immunoaffinity-purified calf or human DNA polymerase by about 6 to 60-fold. Apparently, poly(ADP-ribosyl)ation of DNA polymerase was not necessary for the stimulation. The effects of PARP on DNA polymerase were biphasic: at very low concentrations of DNA, it rather inhibited its activity, whereas, at higher DNA concentrations, PARP greatly stimulated it. The autopoly(ADP-ribosyl)ation of PARP suppressed both its stimulatory and inhibitory effects. By immunoprecipitation with an anti-DNA polymerase antibody, it was clearly shown that PARP may be physically associated with DNA polymerase . Stimulation of DNA polymerase may be attributed to the physical association between the two, rather than to the DNA-binding capacity of PARP, since the PARP fragment containing only the DNA binding domain showed little stimulatory activity. The existence of PARP-DNA polymerase complexes were also detected in crude extracts of calf thymus. 相似文献
36.
The severity of the incidence of the fungal disease, potato scab, varies with different soil groups at the same soil pH. At a soil pH of 5.3, potato scab is easily controlled in soils of western Hokkaido (soil group A) by simply decreasing soil pH, but in soils from eastern Hokkaido (soil group B) it is not so easily controlled. The difference appears to be due to higher levels and exchangeable aluminium in Group A.Addition of sufficient aluminium or ferrous sulfate to a group B soil decreased the incidence of potato scab in a field experiment. Higher levels of aluminium sulfate depressed crop production. It is concluded that aluminium ions control the incidence of potato scab in acid soils. It is suggested that, in soils with low exchange acidity Y1, potato scab can be controlled by adding sufficient aluminium to increase their exchange acidity Y1 to above 7–8. 相似文献
37.
A new regulatory element that augments the Tax-dependent enhancer of human T-cell leukemia virus type 1 and cloning of cDNAs encoding its binding proteins. 总被引:5,自引:3,他引:2 下载免费PDF全文
The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) trans activates the 21-bp enhancer of HTLV-1. A sequence of more than two copies of the 21-bp enhancer is efficiently activated by Tax, but one copy is not activated extensively. Another sequence (TRE-2, positions -163 to -117) adjacent to the 21-bp enhancer in the long terminal repeat of HTLV-1 can enhance a single copy of the 21-bp enhancer activity in trans activation by Tax. This sequence contains motifs related to the Ets- and NF-kappa B-binding sequences, but mutations at these sites indicated that neither is responsive to cooperation with the 21-bp enhancer. A deletion mutation of TRE-2 identified 25 bases at positions -158 to -134 (TRE-2S) as an essential sequence, and TRE-2S was sufficient to give maximum cooperation with one copy of the 21-bp enhancer in trans activation by Tax protein. Using TRE-2S as a probe, we screened a cDNA library of HUT102 cells by the Southwestern (DNA-protein) procedure and isolated two cDNA clones, THP-1 and -2. These two clones encode TRE-2S-binding proteins, and they differ by only an extra 17 amino acids in THP-2. Both THP proteins contain five zinc finger motifs which are strikingly similar to those of the GLI family, an amplified gene product in glyoma cells. The binding site of THP-1 and -2 was GAACCACCCA in TRE-2S, which is highly homologous to the GLI-binding site. These results suggest that binding of THP to TRE-2S may be involved in cooperation with one copy of the 21-bp enhancer in responding to Tax trans activation. 相似文献
38.
Aruto Yoshida Tomoka Hara Hiroshi Ikenaga Makoto Takeuchi 《Glycoconjugate journal》1995,12(6):824-828
By employing a bovine UDP-N-acetylgalactosamine: polypeptideN-acetylgalactosaminyl transferase (O-GalNAc transferase) cDNA as a probe, we isolated four overlapping cDNAs from a porcine lung cDNA library. Both the nucleotide sequence of the porcine cDNA and the predicted primary structure of the protein (559 amino acids) proved to be very similar to those of the bovine enzyme (95% and 99% identity, respectively). Transient expression of the clone in COS-7 cells, followed by enzymatic activity assays, demonstrated that this cDNA sequence encodes a porcine O-GalNAc transferase. The intracellular O-GalNAc transferase activity was increased approximately 100-fold by transfecting cells with the porcine cDNA.Abbreviations O-GalNAc transferase
UDP-N-acetylgalactosamine: polypeptideN-acetylgalactosaminyltransferase
- PCR
polymerase chain reaction
- SDS
sodium dodecyl sulfate
- PAGE
polyacrylamide gel electrophoresis
- GnT-III
UDP-N-acetylglucosamine: -mannoside -1,4N-acetylglucosaminyltransferase III 相似文献
39.
Two key issues in the application of plant-cell-culture technology to the production of valuable secondary metabolites are reviewed: the selection of cell lines with suitable genetic, biochemical and physiological characteristics; and the optimization of bioreactor environments. Although great progress has been made in recent years in the design, selection and optimization of bioreactor hardware, optimization of environmental factors such as medium components, light irradiation and O2 supply needs detailed investigations for each case. With a better understanding of plant cell metabolism and physiology, further developments in cultivation processes, such as process integration and on-line monitoring and control, can be expected in the near future.J.-J. Zhong and J.-T. Yu are with the Research Institute of Biochemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China T. Yoshida is with the International Center of Cooperative Research in Biotechnology (ICBiotech), Faculty of Engineering, Osaka University, Suita, Osaka 565, Japan. 相似文献