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71.
72.
Isao Matsui Masaharu Kamei Shuzo Otani Seiji Morisawa Anthony E. Pegg 《Biochemical and biophysical research communications》1982,106(4):1155-1160
Spermidine acetylase activity was detected in extracts prepared from and there was a marked increase in activity over the early period of growth. This increase reached a maximum 3 h after inoculation and was followed by an increase in ornithine decarboxylase activity. The acetylase was also able to use spermine as a substrate, but not putrescine. With spermidine and acetyl-CoA as substrate, the product formed was exclusively N1-acetyl-spermidine. This is the first evidence for the occurrence in bacteria of spermidine-N1-acetyltransferase, an enzyme which has previously been described in mammalian cells. These results suggest that acetylation of spermidine may be involved in the growth of and in the regulation of its polyamine content. 相似文献
73.
74.
Carboxyphosphonoenolpyruvate phosphonomutase, a novel enzyme catalyzing C-P bond formation. 总被引:4,自引:3,他引:1
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T Hidaka S Imai O Hara H Anzai T Murakami K Nagaoka H Seto 《Journal of bacteriology》1990,172(6):3066-3072
An enzyme catalyzing the formation of an unusual C-P bond that is involved in the biosynthesis of the antibiotic bialaphos (BA) was isolated from the cell extract of a mutant (NP71) of Streptomyces hygroscopicus SF1293. This enzyme, carboxyphosphonoenolpyruvate (CPEP) phosphonomutase, was first identified as a protein lacking in a mutant (NP213) defective in one of the steps in the pathway to BA. The first 30 residues of the amino terminus of this protein were identical to those predicted by the nucleotide sequence of the gene that restored BA production to NP213. The substrate of the enzyme, a P-carboxylated derivative of phosphoenolpyruvate named CPEP, was also isolated from the broth filtrate of NP213 as a new biosynthetic intermediate of BA. CPEP phosphonomutase catalyzes the rearrangement of the carboxyphosphono group of CPEP to form the C-P bond of phosphinopyruvate. 相似文献
75.
Isao Umemura Hirosuke Fukuda Yasuki Fukuda Akira Kimura 《Applied microbiology and biotechnology》1982,15(2):133-137
Summary The regulatory mechanism of ATP regeneration by the glycolytic pathway in Hansenula jadinii cells was investigated by analyzing the initial stage of CDP-choline fermentation. As a result, the on-off of ATP regeneration was found to be determined by the ATP concentration overcoming the inhibitory effect of phosphate buffer on hexokinase activity. The concentration of ATP at the initial stage of fermentation was greatly influenced by the kinds and amounts of glycogen in cells. Based on these results, the regulatory mechanism of ATP regeneration by the glycolytic pathway is discussed in detail. 相似文献
76.
The ubiquinone protein, QP-C, in reduced ubiquinone-cytochrome c reductase (the b?c1-III complex) shows a stable ubisemiquinone radical when the enzyme is reduced by succinate in the presence of catalytic amounts of succinate dehydrogenase and QP-S. At room temperature using EPR technique the redox titration of the b?c1-III complex in the presence of redox dyes or succinate/fumarate couple reveals that the ubisemiquinone radical has a midpoint potential of approximately +67 mV at pH 8.0. Further analysis yields E1 of +83 mV and E2 of +51 mV corresponding to () and () or other electronated forms, respectively. The equilibrium radical concentration has been found to be affected both by pH and succinate/fumarate couple. At pH 9.0 the radical shows the maximal amplitude and stability. Below pH 7.0, little radical was detected. The electron spin relaxation behavior of ubisemiquinone radical, as examined by microwave power saturation, indicates that the ubisemiquinone radical of QP-C is somewhat isolated from other paramagnetic centers. The effects of phospholipids, QP-S, and other agents on ubisemiquinone radical formation as well as the enzymatic activity of QP-C have been studied in detail. 相似文献
77.
Controlled alkaline hydrolysis of 16α-bromo-17-keto steroids , and with potassium carbonate and tetra-n-butylammonium hydroxide (n-Bu4NOH) and synthesis of 2α-hydroxy-3-ones , and by the controlled hydrolysis of the corresponding 2α-bromo-3-ones , and are described. Treatm carbonate in aqueous acetone or with n-Bu4NOH in aqueous dimethylformamide (DMF) gave 16α-hydroxy-17-ones , and in 85–90% yield, respectively. 2α-Hydroxy-3-ones , and were obtained by hydrolysis of the corresponding bromoketones , and in high yields using the above conditions or sodium hydroxide in pyridine or DMF, respectively. Deuterium labeling experiments suggested that equilibration between the 2α-bromoketone and the 2β-bromo isomer precedes the formation of the ketol in which the true intermediate might be the 2β-isomer . However, rearranged androstane derivatives, 3β-hydroxy-2-ones and , were stereoselectively obtained by treatment of the bromoketones and with an excess amount of sodium hydroxide. 相似文献
78.
Isao Katsura 《Journal of molecular biology》1981,146(4):493-512
Viable mutants of bacteriophage lambda having small major tail protein molecules in their virion have been isolated as pseudo-revertants of a defective prophage mutant (defK244) in gene V, which codes for the major tail protein. According to deletion mapping, the defK244 mutation is located near the translation terminal of gene V, whereas some mappable reversion mutations leading to small major tail protein molecules map upstream to defK244 but still downstream to all the amber mutations tested. This suggests (if not proves) that the removable part is located at or near the carboxyl terminal of the major tail protein. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis and buoyant density measurements of the mutant phage particles show that as much as one-third of the major tail protein molecule can be removed without losing its capacity to maintain the total shape and infectivity of the phage particles. In the three-dimensional structure of the tail the removable part of the molecule exists as a protrusion at the outer part of the tail tube according to electron microscopy and hydrodynamic calculations based on sedimentation velocity experiments. 相似文献
79.
80.
Motohiko Hikuma Hiroshi Suzuki Yakeo Yasuda Isao Karube Shuichi Suzuki 《Applied microbiology and biotechnology》1979,8(4):289-297
Summary A microbial electrode consisting of immobilized living whole cells of yeasts, porous membrane and an oxygen electrode was prepared for continuous estimation of biochemical oxygen demand (BOD). Immobilized Trichosporon cutaneum was employed for the microbial electrode sensor for BOD. When a sample solution containing the equivalent amount of glucose and glutamic acid was injected into the sensor system, the current of the electrode decreased markedly with time until steady state was reached. The response time was within 18 min. A linear relationship was observed between the current decrease and the concentration below 41 mg l
– of glucose and 41 mg l
– glutamic acid (5-day BOD 60 mg l
–). The current decrease was reproducible within ± 6% of the relative error when a sample solution containing 27 mg l
– of glucose and 27 mg l
– of glutamic acid (5-day BOD 40 mg l
–) was employed. The microbial electrode sensor was applied to untreated waste waters from a fermentation factory. Good comparative results were obtained between BOD estimated by the microbial electrode and that determined by the conventional 5-day method (regression coefficient was 1.2). Furthermore, the effect of various compounds on BOD estimation was also examined. The current output of the microbial electrode sensor was almost constant for 17 d and 400 tests. 相似文献