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351.
Studies on nitrate reductase of Clostridium perfringens. IV. Identification of metals, molybdenum cofactor, and iron-sulfur cluster 总被引:3,自引:0,他引:3
Nitrate reductase of Clostridium perfringens was purified by an improved method using immuno-affinity chromatography. The purified preparation contained Mo, Fe, and acid-labile sulfide; the Mo content was 1 mol per mol and the Fe 3.7 mol per mol of the enzyme. The inactive enzyme obtained from cells grown in the presence of tungstate did not hold Mo but contained 1 mol of W. The content of Fe was not increased. The presence of molybdenum cofactor in the nitrate reductase was indicated by the formation of molybdopterin form A in the oxidation of the enzyme by iodine and by the complementation of NADPH-nitrate reductase with the heart-treated enzyme in the extract of Neurospora crassa nit-1. The Clostridium nitrate reductase had an absorption maximum at 279 nm and shoulders at 320, 380, 430, and 520 nm. This enzyme seems to contain an iron sulfur cluster since the reduced enzyme showed decreased absorption in visible region. The CD spectrum of the enzyme has a positive peak at 425 nm and negative ones at 310, 360, and 595 nm. It was compared with the CD spectrum of ferredoxin (2Fe-2S or 4Fe-4S cluster) and the nitrate reductase of Plectonema boryanum. 相似文献
352.
353.
Akira Haraguchi 《Ecological Research》1991,6(3):247-263
The relationship between vegetation and seasonal changes in water level was examined in a system of terrestrializing floating
peat mat and pond in a warm temperate zone. The duration of flooding, or drawdown period, is related to vegetation in the
mat. The first process of terrestrialization would be the attenuation of floating-sinking movement of the mat and the consequent
stabilization of water level. Water level at the time when the movement of the mat was attenuated determined the subsequent
vegetation change at the site. Two series of succession according to terrestrialization were recognized, and started from
initial conditions of low and high water levels respectively. Habitats in low initial water levels experienced short flooding
and long drawdown periods. Species changes in the successional series were:Menyanthes trifoliata-Rhynchospora fauriei-Eriocaulon sikokianum-Sphagnum cuspidatum. Submerged peat was experimentally emerged, and the crowded community ofRhynchospora fauriei andEriocaulon sikokianum established within one or two years. Appearance of these species was controlled by the water level of the habitats in winter.
Another series of species changes in terrestrialization process was:Menyanthes trifoliata-Phragmites australis-Carex thunbergii orIsachne globosa. Habitats of these types of vegetation were in the area with relatively high initial water level (long flooding and short
drawdown) when the floating-sinking movement of the mat attenuated. After the temporal paludification, the water level was
lowered by the accumulation of peat in the process of terrestrialization. 相似文献
354.
Stereocontrolled addition of carbon radicals to 4',5'-unsaturated uracil-nucleosides can be accomplished by using organoselenium reagents as a radical source. This provides a new method for C-C bond formation at the 5'-position. 相似文献
355.
356.
H Kumamoto H Tanaka J Ogamino H Suzuki K Haraguchi T Miyasaka 《Nucleic acids symposium series》1999,(42):1-2
Naturally occurring ribonucleosides, uridine and adenosine, were converted to their 3'alpha-CH2CO2Me and 3'alpha-CH2PO(OPh)2 2',3'-dideoxy analogues. The present reaction sequence starts with oxidative cleavage of the 2',3'-cis-diol system, and involves radical-mediated reconstruction of furanose ring as the key step. 相似文献
357.
358.
We found transient hyperthyroidism in the course of hydrocortisone withdrawal in two patients who had undergone unilateral adrenalectomy to resect cortisol-hypersecreting adenoma. A 38-yr-old woman showed clinical thyrotoxicosis 3 months after the operation. Serum T4, T3 and TBG levels were 11.9 micrograms/dl, 310 ng/dl and 16.5 micrograms/ml, respectively. She was given methimazole (MMI) 15 mg/day for 4 weeks. After the cessation of MMI treatment, she eventually recovered to the euthyroid state. The other patient, a 34-yr-old man showed very mild clinical symptoms of hyperthyroidism 2 months after the operation. Serum T4, T3 and TBG levels were 10.4 micrograms/dl, 240 ng/dl and 14.5 micrograms/ml, respectively. In this case, no antithyroid drug was given. Two to three months after the onset of hyperthyroidism, he returned to the euthyroid state spontaneously. We carefully eliminated the possibility of factitious thyrotoxicosis in both cases. They had neither neck pain nor fever. Both had low radioactive iodine uptake by the thyroid. Therefore, we diagnosed them as painless thyroiditis induced after the resection of hypersecreting adrenal adenoma. 相似文献
359.
Akira Haraguchi 《Ecological Research》1992,7(3):205-212
A relationship was sought between species distribution and seasonal change in the redox property of peat in a floating mat
in Mizorogaike Pond, central Japan. The mat surface experienced an annual submergence-emergence cycle due to its sinking-rising
movement. Redox potential (Eh) of the surface peat showed little difference between communities in the mat in the submergence
season (January–June) and early emergence season (July–August). However variation in Eh among communities was clear in the
late emergence season (September–December). Among seven communities in the floating mat, theMenyanthes trifoliata-Rhynchospora fauriei, M. trifoliata-Eriocaulon sikokianum-E. bondoense f.pilosum, Sphagnum cuspidatum andM. trifoliata-Carex thunbergii communities had high Eh (400–600 mV) in the late emergence season, while theMenyanthes trifoliata andPhragmites australis-M. trifoliata communities had lower Eh (200–400 mV). TheM. trifoliata-Isachné globosa community was intermediate (300–500 mV). The earlier the emergence of the peat surface began, the higher the Eh became in
the late emergence season. 相似文献