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31.
Hiroshi Kagawa Toshihisa Kuwajima Hiroshi Asai 《Biochimica et Biophysica Acta (BBA)/General Subjects》1974,338(2):496-504
A fluorescent ATP analog, β-naphthyl triphosphate, was hydrolyzed to β-naphthyl diphosphate and orthophosphate by heavy meromyosin ATPase. In the process of hydrolysis the fluorescence intensity of β-naphthyl triphosphate changed remarkably. Thus, the rate of β-naphthyl triphosphate hydrolysis is evaluated directly and continuously by measuring the time course of fluorescence intensity.In the presence of Ca2+, the Michaelis constant (Km) of β-naphthyl triphosphate hydrolysis by heavy meromyosin was similar to that of ATP hydrolysis. While, in the presence of Mg2+ the Km of β-napthyl triphosphate hydrolysis was 9.0·10−6 M, much larger than the value of ATP hydrolysis, indicating that the apparent affinity of the enzyme for β-naphthyl triphosphate is less than that for ATP.The pH dependence of β-naphthyl triphosphatase activity resembled that of ATPase activity, suggesting a similarity in the mechanism of hydrolysis of the two substrates. 相似文献
32.
K Kopaczyk J Asai D W Allmann T Oda D E Green 《Archives of biochemistry and biophysics》1968,123(3):602-621
33.
Ichiro Shimada Yuji Maki Hiroshi Sugiyama 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,165(2):193-196
Summary
N-Acylation changed nonstimulatory Dvaline into a clear stimulant of the sugar receptor of the fleshfly,Boettcherisca peregrina. Of theN-acyl-D-valines, the most stimulatory wasN-acetyl-D-valine. Similar changes into stimulants were also observed in other aliphatic amino acids such as leucine and methionine. Dose-response curves ofN-acetyl-D-valine suggested an increase of binding affinity, compared with that ofN-acetyl-L-valine. By treatment experiment with pronase 10 mg/ml, stimulatoryN-acetyl-D-amino acids were suggested to react with the specific alkyl site (R site), which was presumed to discriminate between L- and D-forms of the amino acids through steric hindrance between its own spatial barrier and D-amino acids (Shimada and Isono 1978; Shimada and Tanimura 1981).This change of chiral recognition cannot be explained by simple steric hindrance at the R site. It means, instead, that a hydrophobic subsite rather than a spatial barrier must be postulated. 相似文献
34.
Ten distinct monoclonal antibodies (MAbs) against alpha toxin of Clostridium perfringens were produced by the fusion of SP2/O with spleen cells of mice immunized with alpha toxoid, and alpha toxin mixed with or without ethylenediamine-tetraacetate (EDTA). The antibody activity was evaluated by antigen-binding activity in an enzyme linked immunosorbent assay (ELISA), by phospholipase C (PLC)-neutralizing activity using both egg yolk lecithin and p-nitrophenylphosphoryl-choline (PNPPC) hydrolysis reactions and by anti-lethal activity in mice. Since the toxin-neutralizing activities of each MAb were not parallel, it has been suggested that the three biological activities may not be located in the same site in the toxin molecule. This report also describes the development of a simple purification of the toxin by affinity chromatography and a sensitive immunoassay for quantitation of the toxin using the monoclonal antibody. 相似文献
35.
Nakayama Ishizue; Miyazawa Takeshige; Kobayashi Masatomo; Kamiya Yuji; Abe Hiroshi; Sakurai Akira 《Plant & cell physiology》1990,31(2):195-200
The effects of a novel plant growth regulator (PGR) prohexadionecalcium (BX-112; calcium 3,5-dioxo-4-propionylcyclohexanecarboxylate)on shoot elongation caused by exogenously applied GA1, GA3,GA4) GA19 and GA20 were investigated in rice (Oryza sativa L.cv. Nihonbare and cv. Tan-ginbozu) seedling test. Dependingon the dose, BX-112 reduced shoot elongation in both cultivarscaused by GA19 and GA20, but not by GA1. When a high dose ofBX-112 (e.g. 250 ng/plant and over) was applied with GA1, orGA4, shoot elongation was even promoted. This promotive effect,however, was not observed with GA3. These results suggest thatBX-112 inhibits gibberellin (GA) biosynthesis in the rice plantat the 3ß- and 2ß-hydroxylation of GAs,namely steps of activation and inactivation, respectively. (Received September 6, 1989; Accepted November 27, 1989) 相似文献
36.
Application of ozone disinfection to remove Enterococcus seriolicida, Pasteurella piscicida, and Vibrio anguillarum from seawater. 总被引:2,自引:1,他引:1
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H Sugita T Asai K Hayashi T Mitsuya K Amanuma C Maruyama Y Deguchi 《Applied microbiology》1992,58(12):4072-4075
Survival of bacterial fish pathogens, including Enterococcus seriolicida, Vibrio anguillarum, and Pasteurella piscicida, in ozonated seawater was determined in a batch system. Bacterial counts of all fish pathogens decreased at more than 0.040 to 0.060 mg of total residual oxidants (TROs) per liter, whereas no decrease in viable counts was observed at less than 0.018 to 0.028 mg of TROs per liter. The 99% inactivation point was achieved at concentrations of 0.111 mg/liter for E. seriolicida, 0.063 mg/liter for P. piscicida, and 0.064 mg/liter for V. anguillarum within 1 min. Moreover, the mean 99 and 99.9% killing concentration-contact time (C.t) products were 0.123 and 0.186 mg.min/liter for E. seriolicida, 0.056 and 0.084 mg.min/liter for P. piscicida, and 0.081 and 0.123 mg.min/liter for V. anguillarum, respectively. However, the mean 99 and 99.9% C.t products for the mixed population in coastal seawater were 0.200 and 0.621 mg.min/liter. These results strongly suggest that ozone treatment at more than 1.0 mg of TROs per liter for several minutes is able to disinfect seawater for mariculture efficiently. 相似文献
37.
Bacterial dissolution of pyrite by Thiobacillus ferrooxidans 总被引:5,自引:0,他引:5
The kinetics of the dissolution of pure pyrite (FeS2) particles by Thiobacillus ferrooxidans were studied both theoretically and experimentally. Adsorption and dissolution experiments were carried out at 30 °C and pH=2, by using a batch reactor. The adsorption process of T. ferrooxidans to pyrite surface was rapid in comparison with the bacterial dissolution process. The experimental results for the adsorption equilibrium were well correlated by the Langmuir type isotherm. The growth rate of adsorbed bacteria was found to be proportional to the product of the number of adsorbed cells and the fraction of solid surface unoccupied by cells. A new kinetic model for the bacterial dissolution was presented, and shown to correlate well with the experimental data for the rate of bacterial dissolution and for the time variation in the number of cells in the liquid phase. The specific growth rate of adsorbed bacteria was also evaluated.List of Symbols
f
weight fraction of iron in pyrite
-
K
A
m3/cells
equilibrium constant for cell adsorption
-
R
A
cells/d m3-mixture
growth rate of bacteria adsorbed on solid surface
-
R
L
cells/d m3-mixture
growth rate of free bacteria in the liquid phase
-
t d
time
-
V m3
volume of solid-liquid mixture
-
W kg
weight of pyrite
-
W
0 kg
initial weight of pyrite
-
X
A
cells/kg-solid
number of adsorbed cells on solid surface
-
X
Am
cells/kg-solid
maximum adsorption capacity
-
X
L
cells/m3-liquid
number of free cells existing in the liquid phase
-
X
T
cells/m3-mixture
total number of cells
-
X
TO
cells/m3
initial total number of cells
-
Y
A
cells/kg-FeS2
growth yield of adsorbed bacteria
-
Y
L
cells/kg-Fe2+
growth yield of free bacteria
- [Fe]
T
kg/m3-liquid
concentration of total iron in the liquid phase
-
fraction of pyrite dissolved
-
V
fraction of adsorption sites unoccupied by cells
-
A
d–1
specific growth rate of adsorbed bacteria
-
L
d–1
specific growth rate of free bacteria
-
volume fraction of solid particles in solid-liquid mixture 相似文献
38.
The DNA replication priming protein, PriA, is required for homologous recombination and double-strand break repair. 总被引:26,自引:5,他引:21
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The PriA protein, a component of the phiX174-type primosome, was previously shown to be essential for damage-inducible DNA replication in Escherichia coli, termed inducible stable DNA replication. Here, we show that priA::kan null mutants are defective in transductional and conjugational homologous recombination and are hypersensitive to mitomycin C and gamma rays, which cause double-strand breaks. The introduction of a plasmid carrying the priA300 allele, which encodes a mutant PriA protein capable of catalyzing the assembly of an active primosome but which is missing the n'-pas-dependent ATPase, helicase, and translocase activities associated with PriA, alleviates the defects of priA::kan mutants in homologous recombination, double-strand break repair, and inducible stable DNA replication. Furthermore, spa-47, which was isolated as a suppressor of the broth sensitivity of priA::kan mutants, suppresses the Rec- and mitomycin C sensitivity phenotypes of priA::kan mutants. The spa-47 suppressor mutation maps within or very near dnaC. These results suggest that PriA-dependent primosome assembly is crucial for both homologous recombination and double-strand break repair and support the proposal that these processes in E. coli involve extensive DNA replication. 相似文献
39.
Katsunori Kohda Yuji Tsuji Masahiro Takagi Tadayuki Imanaka 《Biotechnology letters》1996,18(9):1061-1066
Genes homologous to groES and groEL, which are recognized as molecular chaperone genes, from Bacillus stearothermophilus SIC1 were cloned and sequenced. By addition of GroES, GroEL and ATP in vitro, remaning activity of the alcohol dehydrogenase from Saccharomyces cerevisiae after heat treatment at 50°C for 6 min was improved from 55% to 90%. Furthermore, even though inclusion bodies were formed when a single chain Fv(sFv) was expressed in E. coli cells, during in vivo coexpression with molecular chaperone, a significant amount of the antibody protein could be recovered from the soluble fraction. 相似文献
40.
Tokuma Yanai Haruaki Taniguchi Hiroki Sakai Kazunori Yoshida Naoto Kimura Akira Katou Yuji Oishi Toshiaki Masegi 《Journal of medical primatology》1996,25(4):309-312
Abstract: A rare case of bilateral adrenal myelolipomas in a female cotton-top tamarin is reported. Large bilateral masses in the adrenal glands were composed of mature adipose cells containing varying amounts of hematopoietic cells of the myeloid, erythroid, and megakaryocyte series. The gross and histologic features of this case closely resemble human “giant” adrenal myelolipomas. 相似文献