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991.
Ueda M Asano T Nakazawa M Miyatake K Inouye K 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2008,150(1):125-130
Novel raw-starch-digesting and cold-adapted alpha-amylases (Amy I and Amy II) from the earthworm Eisenia foetida were purified to electrophoretically homogeneous states. The molecular weights of both purified enzymes were estimated to be 60,000 by SDS-PAGE. The enzymes were most active at pH 5.5 and 50 degrees C and stable at pH 7.0-9.0 and 50-60 degrees C. Both Amy I and II exhibited activities at 10 degrees C. The enzymes were inhibited by metal ions Cu(2+), Fe(2+), and Hg(2+), and hydrolyzed raw starch into glucose, maltose and maltotriose as end products. 相似文献
992.
Repulsive and attractive semaphorins cooperate to direct the navigation of cardiac neural crest cells 总被引:1,自引:0,他引:1
Toyofuku T Yoshida J Sugimoto T Yamamoto M Makino N Takamatsu H Takegahara N Suto F Hori M Fujisawa H Kumanogoh A Kikutani H 《Developmental biology》2008,321(1):251-262
The cardiac neural crest, a subpopulation of the neural crest, contributes to the cardiac outflow tract formation during development. However, how it follows the defined long-range migratory pathway remains unclear. We show here that the migrating cardiac neural crest cells (NCCs) express Plexin-A2, Plexin-D1 and Neuropilin. The membrane-bound ligands for Plexin-A2, Semaphorin (Sema)6A and Sema6B, are expressed in the dorsal neural tube and the lateral pharyngeal arch mesenchyme (the NCC “routes”). Sema3C, a ligand for Plexin-D1/neuropilin-1, is expressed in the cardiac outflow tract (the NCC “target”). Sema6A and Sema6B repel neural crest cells, while Sema3C attracts neural crest cells. Sema6A and Sema6B repulsion and Sema3C attraction are diminished either when Plexin-A2 and Neuropilin-1, or when Plexin-D1, respectively, are knocked down in NCCs. When RNAi knockdown diminishes each receptor in NCCs, the NCCs fail to migrate into the cardiac outflow tract in the developing chick embryo. Furthermore, Plexin-A2-deficient mice exhibit defects of cardiac outflow tract formation. We therefore conclude that the coordination of repulsive cues provided by Sema6A/Sema6B through Plexin-A2 paired with the attractive cue by Sema3C through Plexin-D1 is required for the precise navigation of migrating cardiac NCCs. 相似文献
993.
Sakaguchi M Takezawa M Nakazawa R Nozawa K Kusakawa T Nagasawa T Sugahara Y Kawakita M 《Journal of biochemistry》2008,143(5):625-632
A thermophilic serine protease, Aqualysin I, from Thermus aquaticus YT-1 has two disulphide bonds, which are also found in a psychrophilic serine protease from Vibrio sp. PA-44 and a proteinase K-like enzyme from Serratia sp. at corresponding positions. To understand the significance of these disulphide bonds in aqualysin I, we prepared mutants C99S, C194S and C99S/C194S (WSS), in which Cys69-Cys99, Cys163-Cys194 and both of these disulphide bonds, respectively, were disrupted by replacing Cys residues with Ser residues. All mutants were expressed stably in Escherichia coli. The C99S mutant was 68% as active as the wild-type enzyme at 40 degrees C in terms of k(cat) value, while C194S and WSS were only 6 and 3%, respectively, as active, indicating that disulphide bond Cys163-Cys194 is critically important for maintaining proper catalytic site conformation. Mutants C194S and WSS were less thermostable than wild-type enzyme, with a half-life at 90 degrees C of 10 min as compared to 45 min of the latter and with transition temperatures on differential scanning calorimetry of 86.7 degrees C and 86.9 degrees C, respectively. Mutant C99S was almost as stable as the wild-type aqualysin I. These results indicate that the disulphide bond Cys163-Cys194 is more important for catalytic activity and conformational stability of aqualysin I than Cys67-Cys99. 相似文献
994.
995.
T Fukushima K Mochizuki H Yamazaki Y Watanabe S Yamada T Aoyama Y Sakurai H Mori M Nakazawa 《Jikken dobutsu》1990,39(2):187-192
Pentatrichomonas sp. from the feces of beagles was cultured axenically, and identified as P. hominis. The culture medium used was slightly modified Diamond's medium supplemented with chicken liver extract and rifampicin. Based upon good proliferation after inoculating only a few organisms in this medium, a fecal examination method employing cultivation was developed. Resistance of the trichomonad against disinfectants and metronidazole was tested, and it was found that the protozoan was rather susceptible. After oral administration of the organism to mice and rats, all the treated animals were infected. Since two types of the trichomonad, moving and non-moving, were detected, the presence of any type resistant to standing or drying was ruled out. A possible route of trichomonad infection to beagles is discussed. 相似文献
996.
The reason for the differences in phototoxic potential between the 5 quinolone antibacterial agents lomefloxacin, enoxacin, ciprofloxacin, ofloxacin and DR-3355 (the s-isomer of ofloxacin) in mice was investigated. Superoxide anion, hydrogen peroxide (H2O2), and bleaching of p-nitrosodimethylaniline (B-NDMA) were detected in quinolone solutions during irradiation with ultraviolet-A (UVA). Apparent levels of H2O2 and the B-NDMA per mole of quinolone paralleled the phototoxic potentials in the mice. The N-NDMA induced by quinolones and UVA was inhibited partially by treatment with D-mannitol and dimethylsulfoxide, and also with diethylenetriamine-pentaaceticacid (DTPA), suggesting that Haber-Weiss and Fenton reactions occurred. UVA concentration-dependently increased the level of the B-NDMA in H2O2 solution and the swelling in the ear pretreated by intra-auricular injection of H2O2. Both augmentations were inhibited by DTPA or DMSO. The swelling induced by the 5 quinolones and UVA was completely inhibited by pretreatment with dimethylsulfoxide. Oxygen consumption was detectable during the photodegradation, and increased with time. These results showed that the phototoxic potentials of the 5 quinolones were probably related to the amounts of toxic oxygens generated in the target cells during irradiation. 相似文献
997.
Toshiharu Nagatsu Tokio Yamaguchi Takeshi Kato Takashi Sugimoto Sadao Matsuura Miki Akino Shoichiro Tsushima Nobuhiko Nakazawa Hiroshi Ogawa 《Analytical biochemistry》1981,110(1):182-189
Specific antibodies against l-erythro-biopterin have been prepared in rabbits using the conjugates to bovine serum albumin. The antiserum against l-erythro-biopterin distinguished among l-erythro-tetrahydro- or 7,8-dihydro-biopterin, the other three stereoisomers of biopterin, d-erythro-neopterin, folic acid, and other synthetic pteridines. Using the specific antiserum against l-erythro-biopterin, a radioimmunoassay has been developed to measure the biopterin concentrations in urine, serum, cerebrospinal fluid, and tissues. The conjugate of l-erythro-biopterin with tyramine, 4-hydroxy-2-[2-(4-hydroxyphenyl)ethylamino]-6-(l-erythro-1,2-dihydroxypropyl)pteridine (BP-TYRA), was synthesized and labeled with 125I as the labeled ligand for the radioimmunoassay. BP-125I-TYRA had similar binding affinity as the natural l-erythro-biopterin and was thus permitted to establish a highly sensitive radioimmunoassay for biopterin. The limit of sensitivity of the radioimmunoassay with BP-125I-TYRA as labeled ligand was 0.5 pmol. The total concentration of biopterins, i.e., biopterin, 7,8-dihydro-, quinonoid dihydro and tetrahydrobiopterins, in the biological samples was obtained by iodine oxidation under acidic conditions prior to the radioimmunoassay, whereas iodine oxidation under alkaline conditions gave the concentration only of the former two. Biopterin in urine could be measured directly using 1 μl of urine, but a pretreatment with a small Dowex 50-H+ column was required for serum, cerebrospinal fluid, and brain tissues. 相似文献
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