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121.
Hiroshi Kase Haruo Tanaka Kiyoshi Nakayama 《Bioscience, biotechnology, and biochemistry》2013,77(13):2089-2096
Fifteen strains of bacteria were treated with ultraviolet light or N-methyl-N′-nitro-N-nitrosoguanidine to derive auxotrophic mutants, which were screened for their ability to produce l-threonine. A number of auxotrophs were derived from each strain. Among them, those which produced a large amount of l-threonine were found in Aerobacter aerogenes, Serratia marcescens and Escherichia coli, the members of the family Enterobacteriaceae. Nutritional requirements of these threonine producers were proved to be methionine, lysine, or α, ε-diaminopimelic acid (DAP).In A. aerogenes and E. coli, double and triple auxotrophs were derived with futher mutational treatment. As a, rule, imposition of additional block led to the increase of l-threonine production. In E. coli, many triple auxotrophs (DAP?, Met?, He?) and their isoleucine revertants were screened for their ability to produce l-threonine. Enhancement of l-threonine production was achieved with these mutants.One of the isoleucine revertants, KY8280, was used to investigate some cultural conditions. As a result, l-threonine accumulation reached to a level of 13.8 mg/ml with the medium containing 7.5% fructose. 相似文献
122.
Mitsuru Niwano Etsuko Mirumachi Masakazu Uramoto Kiyoshi Isono 《Bioscience, biotechnology, and biochemistry》2013,77(5):1359-1360
The Maillard reaction of DNA with ketoses was investigated. Several days of incubation of d-fructose 6-phosphate with deoxyribonucleotides or with polymer DNA in an aqueous buffer resulted in the formation of chromophores and fluorophores. Aminoguanidine and sodium cvanoborohydride inhibited the formation of fluorophores. Transition metal ions such as Cu2+, Fe3+, Fe2+, or Mn2 + promoted the formation of chromophores and fluorophores. Metal-chelating agents such as DETAPAC, citrate, and Desferal inhibited the formation of fluorophores. Superoxide dismutase and catalase also inhibited the formation of fluorophores. The transition metal ion-catalyzed autoxidation of d-fructose 6-phosphate or of the Heyns rearrangement products were to be partially involved in the glycation of DNA and subsequent formation of chromophores and of fluorophores. 相似文献
123.
Masaki Nakahara Nobuaki Kitahara Kiyoshi Hamano Mamoru Arat Hiroshi Okazaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):1821-1826
Studies on lipopolysaccharide (LPS) from the cells of Proteus mirabilis RMS-203 were focused upon reduction of lethal toxicity and of pyrogenicity by biological and chemical modification. A heptoseless mutant, strain N-434, was isolated by the use of phage resistancy as a tool. LPS from that heptoseless mutant was completely deficient in neutral sugars and mainly composed of 2-keto-deoxy-octonic acid (KDO), glucosamine and fatty acids. It revealed almost the same antitumor activity as LPS of the wild type but it was less toxic and less pyrogenic.Hydroxylaminolysis and reduction with LiAlH4 resulted in removal of fatty acids from LPS accompanied with decrease in lethal toxicity and antitumor acitivity but not in pyrogenicity.Lipid A fractions showed almost the same antitumor activity as intact LPS but less lethality and less pyrogenicity. 相似文献
124.
The present report describes the successful isolation procedure and some physico-chemical properties of an unknown blue-violet fluorescent substance existing in spinach leaves. Through the isolation steps of water extraction of leaves (200 kg), active carbon adsorption, extraction by organic solvents, and column chromatographies with various adsorbents and ion exchange resins, a purified compound was obtained in colorless planeary crystal of long parallelogram (40 mg; mp. 195°C; C13H17O9N1). The UV-, IR- and NMR-spectra, the results of organic tests, and behaviors on chromatographies and electrophoreses are presented. 相似文献
125.
Kiyoshi Isono Junsaku Nagatsu Kimie Kobinata Kazuya Sasaki Saburo Suzuki 《Bioscience, biotechnology, and biochemistry》2013,77(2):190-199
Seven additional components, polyoxins C, D, E, F, G, H and I were isolated from polyoxin complex. They have molecular formulae corresponding to C11H15N3O8, C17H23N5O14, C17H23N5O13, C23H30N6O15, C17H25N5O12, C23H32N6O13 and C19H24N4O12, respectively. These polyoxins except inactive polyoxins C and I were highly active against various kinds of phytopathogenic fungi. The close structural similarity among them including polyoxins A and B is also discussed. 相似文献
126.
Hiroshi Hagino Hajime Yoshida Fumio Kato Yuko Arai Ryoichi Katsumata Kiyoshi Nakayama 《Bioscience, biotechnology, and biochemistry》2013,77(9):2001-2005
Polyauxotrophic mutants of Corynebacterium glutamicum which have additional requirements to L-phenylalanine were derived from L-tyrosine producing strains of phenylalanine auxotrophs, C. glutamicum KY 9189 and C. glutamicum KY 10233, and screened for L-tyrosine production. The increase of L-tyrosine production was noted in many auxotrophic mutants derived from both strains. Especially some double auxotrophs which require phenylalanine and purine, phenylalanine and histidine, or phenylalanine and cysteine produced significantly higher amounts of L-tyrosine compared to the parents, A phenylalanine and purine double auxotrophic strain LM–96 produced L-tyrosine at a concentration of 15.1 mg per ml in the medium containing 20% sucrose. L-Tyrosine production by the strain decreased at high concentrations of L-phenylalanine. 相似文献
127.
Hiroki Hayase Nobumoto Watanabe Chung Liang Lim Toshihiko Nogawa Keisuke Komatsuya Kiyoshi Kita 《Bioscience, biotechnology, and biochemistry》2013,77(4):633-635
Quinomycin A and its derivatives were identified as potent antimalarial (Plasmodium falciparum) agents in a screen of the RIKEN NPDepo chemical library. IC50 values of quinomycin A and UK-63,598 were approximately 100 times lower than that of the antimalarial drug chloroquine. This activity was mitigated by the addition of plasmid DNA, suggesting that these compounds act against parasites by intercalating into their DNA. 相似文献
128.
Hajime Yoshida Yoshitake Tanaka Kiyoshi Nakayama 《Bioscience, biotechnology, and biochemistry》2013,77(9):2121-2126
Six strains of bacteria belonging to Vibrio and Pseudomonas were selected as good producers of L-DOPA from L-tyrosine out of various bacteria. The condition for the formation of L-DOPA by Vibrio tyrosinaticus ATCC 19378 was examined and the following results were obtained. (1) Intermittent addition of L-tyrosine in small portions gave higher titer of L-DOPA than single addition of L-tyrosine. (2) Higher amount of L-DOPA was produced in stationary phase of growth than in logarithmic phase. (3) Addition of antioxidant, chelating agent or reductant such as L-ascorbic acid, araboascorbic acid, hydrazine, citric acid and 5-ketofructose increased the amount of L-DOPA formed. (4) L-Tyrosine derivatives such as N-acetyl-L-tyrosine amide, N-acetyl-L-tyrosine, L-tyrosine amide, L-tyrosine methyl ester and L-tyrosine benzyl ester were converted to the corresponding L-DOPA derivatives.In the selected condition about 4 mg/ml of L-DOPA was produced from 4.3 mg/ml of L-tyrosine. 相似文献
129.
Vimbai Samukange Masayuki Kamo Kiyoshi Yasukawa 《Bioscience, biotechnology, and biochemistry》2013,77(9):1522-1528
Neutral salts activate and stabilize thermolysin. In this study, to explore the mechanism, we analyzed the interaction of 8-anilinonaphthalene 1-sulphonate (ANS) and thermolysin by ANS fluorescence. At pH 7.5, the fluorescence of ANS increased and blue-shifted with increasing concentrations (0–2.0?μM) of thermolysin, indicating that the anilinonaphthalene group of ANS binds with thermolysin through hydrophobic interaction. ANS did not alter thermolysin activity. The dissociation constants (Kd) of the complex between ANS and thermolysin was 33?±?2?μM at 0?M NaCl at pH 7.5, decreased with increasing NaCl concentrations, and reached 9?±?3?μM at 4?M NaCl. The Kd values were not varied (31?34?μM) in a pH range of 5.5?8.5. This suggests that at high NaCl concentrations, Na+ and/or Cl– ions bind with thermolysin and affect the binding of ANS with thermolysin. Our results also suggest that the activation and stabilization of thermolysin by NaCl are partially brought about by the binding of Na+ and/or Cl– ions with thermolysin. 相似文献
130.
Studies were made on the incorporation of 14C of acetate-1-14C into the lipids of the liver and carcass, and changes in the concentrations of nucleotides, citric acid, and free fatty acids in the liver, using rats fed diets consisting of starch and casein, or starch and corn oil, at different ratios. Lipogenesis was stimulated with an increase in the content of starch both in the starch-casein and starch-corn oil diets. There was a rapid drop in lipogenesis in rats fed the diet with a little increment in the content of corn oil. Lipogenesis decreased gradually with an increment in the content of casein in the starch-casein diet. A positive correlation was found between lipogenesis and the level of ATP in the liver. The concentration of citric acid decreased with an increase in lipogenesis in the liver. Changes in dietary composition did not produce any significant alteration in the concentration of free fatty acids in the liver. 相似文献