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11.
The inhibitory effects of proline-containing peptides and their derivatives on prolyl endopeptidases from Flavobacterium meningosepticum and bovine brain were compared. Replacement of the carboxyl terminal proline in N-blocked peptides with prolinal resulted in remarkable decreases in Ki values for both prolyl endopeptidases. Further reduction of the prolinal to prolinol led to a decrease in their inhibitory effects. Z-Pro-, Z-Val-, and Suc-Pro-prolinals were similarly inhibitory for both the enzymes with Ki values of nM order. However, the inhibitory effects of Z-Pyr-prolinal and Boc-Pro-prolinal on these enzymes were significantly distinguished: they strongly inhibited the mammalian prolyl endopeptidase with Ki values of nM order, while the Ki values of these compounds for the microbial enzyme were only of microM order. These results suggest that there are some structural differences in the S2 and S3 subsites between the two enzymes, though their substrate specificities are apparently indistinguishable. 相似文献
12.
Identification of an Rts1 DNA fragment conferring temperature-dependent instability to vector plasmids 总被引:4,自引:0,他引:4
The multiphenotypic drug resistance factor Rts1 expresses a temperature-dependent instability characteristic. This plasmid was digested with the restriction enzyme BamHI. A DNA fragment with a molecular weight of 5.6 MDa (the H fragment) was inserted into plasmid pBR322 (pFK896) or into pSC105 (pYH156) at the BamHI site. These plasmids were unstable at 42 degrees C but stable at 32 degrees C. A restriction-enzyme map of the H fragment was constructed and the instability phenotype (Tdi) was localized to a DNA fragment with 0.5 MDa molecular weight. The temperature-dependent loss of the unstable plasmid pFK896 is abrupt and no gradual plasmid loss of this multicopy recombinant plasmid is observed. The possibility that the Tdi phenotype is due to overgrowth of R- cells was eliminated. 相似文献
13.
A. Ajima T. Yoshimoto K. Takahashi Y. Tamaura Y. Saito Y. Inada 《Biotechnology letters》1985,7(5):303-306
Summary A hydrophobic substrate, 10-hydroxydecanoic acid having two functional groups (–OH and –COOH) in the molecule, was polymerized by ester bond formation with the polyethylene glycol-modified lipase in a transparent benzene solution. The polymer of 10-hydroxydecanoic acid was linearly elongated under a quite mild condition. 相似文献
14.
Early replicative intermediates of Escherichia coli chromosome isolated from a membrane complex. 总被引:5,自引:3,他引:2 下载免费PDF全文
The replication origin region of the Escherichia coli chromosome was isolated from an outer membrane fraction. The chromosome was further purified by centrifugation in a cesium chloride gradient. Early replicative intermediates were enriched in the preparation when cytosine-1-beta-arabinofuranoside was added to the culture at the time of initiation of chromosome replication. DNA fragments with an eye structure having two branches of less than 400-500 bp in length were associated with components that were removed by phenol treatment. We conclude that the replication fork usually proceeds counter-clockwise toward the unc operon in the earliest period of replication. 相似文献
15.
The quantity of translatable mRNA of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) in primary cultures of adult rat hepatocytes subjected to different hormonal conditions was determined with a reticulocyte-lysate, cell-free system. The level of glucose-6-phosphate dehydrogenase mRNA was about 5-fold higher in the presence of insulin than in its absence. This increase of glucose-6-phosphate dehydrogenase mRNA reached a maximum 12 h after the addition of insulin. The maximum level of induction of glucose-6-phosphate dehydrogenase mRNA required 10(-8) M insulin. Glucagon and triiodothyronine had no effect on the glucose-6-phosphate dehydrogenase mRNA level. The increase of glucose-6-phosphate dehydrogenase activity correlated with the increase in level of mRNA of this enzyme. This suggests that the changes in glucose-6-phosphate dehydrogenase activity in response to the above hormonal changes are primarily due to changes in the amount of mRNA coding for this enzyme. 相似文献
16.
Flavonoids: potent inhibitors of arachidonate 5-lipoxygenase 总被引:2,自引:0,他引:2
T Yoshimoto M Furukawa S Yamamoto T Horie S Watanabe-Kohno 《Biochemical and biophysical research communications》1983,116(2):612-618
Various flavonoids were found to be relatively selective inhibitors of arachidonate 5-lipoxygenase which initiates the biosynthesis of leukotrienes with the activity of slow reacting substance of anaphylaxis. Cirsiliol (3',4',5-trihydroxy-6,7-dimethoxyflavone) was most potent, and the enzyme partially purified from rat basophilic leukemia cells was inhibited by 97% at a concentration of 10 microM (IC50, about 0.1 microM). 12-Lipoxygenases from bovine platelets and porcine leukocytes were also inhibited but at higher concentrations (IC50, about 1 microM), and fatty acid cyclooxygenase purified from bovine vesicular gland was scarcely affected. The compound at 10 microM suppressed by 99% the immunological release of slow reacting substance of anaphylaxis from passively sensitized guinea pig lung (IC50, about 0.4 microM). 相似文献
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Tadao Niijima Takashi Umeda Manabu Kuriyama Hiroyuki Ohmori Yohsuke Matsumura Tomoyasu Tsushima Toyoko Tanahashi Jun Yoshimoto Toshihiko Asahi Norimasa Ike Taiichiro Johsen Noritaka Ishido Naoki Mitsuhata Takeshi Uyama Hiroyoshi Tanaka Hideo Ueda Jisaburo Sakatoku Norio Yamamoto Kazuo Nagata Yukitoshi Fujita Masaaki Morioka Kazuo Kurokawa Susumu Kagawa Tomoyuki Ishibe Yasutoshi Himeno Toyofumi Ueda 《Cancer immunology, immunotherapy : CII》1989,30(2):81-85
Summary In order to examine its clinical efficacy, recombinant human interferon- (rIFN-) was instilled intravesically into 51 patients with superficial bladder cancer. Ten patients, who received intermittent intravesical instillation at a dose of (3–36) × 106 U rIFN- on days 1–3 every week, showed no response. Thirty-two patients received intravesical instillation at a dose of (3–36) × 106 U every day for 10–20 days. Eight patients showed partial response, indicating an efficacy rate of 25%. Nine patients received divided doses of 18 × 106 U twice a day every day for 10–20 days. Six patients showed partial response, indicating an efficacy rate of 67%. This value was significantly higher than that obtained by administering divided doses. The response to intravesical instillation therapy with rIFN- varies with treatment protocol. Frequent and longer exposure to rIFN- may induce better regression of superficial bladder cancer. Six incidences of side-effects were found in five cases (9.8%): pollakiuria in one, pain on micturition in two, fever in two, and eruption in one case. All of these side-effects were slight and reversible after drug withdrawal. Laboratory tests showed only a few changes with low severity. Thus, rIFN- is potentially a new drug for instillation therapy of superficial bladder cancer, in view of the absence of adverse effects. 相似文献
20.
A neutral protease from Bacillus subtilis var. amylosacchariticus was modified with tetranitromethane (TNM) at pH 8.0 for 1 h at 25 degrees C, by which treatment the proteolytic activity toward casein was markedly reduced, whereas activity changes toward N-blocked peptide substrates were variable depending upon the substrate used. The modified enzyme was digested with a Staphylococcus aureus V8 protease at pH 7.9 and the resultant peptides were separated by HPLC. Two peptides which contain nitrotyrosyl residue(s) were purified. One of the peptides was found to have an amino acid sequence of Thr-Ala-Asn-Leu-Ile-Tyr-Glu, which corresponds to residue Nos. 153-159 of the neutral protease, and Tyr-158 was identified as PTH-nitrotyrosine. The other one was the amino-terminal peptide of residue Nos. 1-22, and Tyr-21 was shown to be nitrated. From a comparison with the active site structure of thermolysin, which is a zinc metalloprotease with a high sequence homology to B. subtilis neutral proteases, nitration of Tyr-158 was inferred to be closely related to the activity changes of the neutral protease from B. subtilis var. amylosacchariticus. 相似文献