Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To study the effect of fertilizer N and Ca on tomato plant, a pot experiment was conducted with meadow soil in Shenyang. The results showed that under the experimental condition, the N contents in stems, leaves and fruits decreased gradually along with the growth stages. For all treatments, the NO3(-)-N content in fruits, which was within the raw eatable standard, had a positive correlation to N fertilization level. Adequate application of Ca was useful to control the NO3(-)-N content. The response of N contents in stems, leaves and fruits to fertilizer N and Ca was in line with the law of diminishing marginal returns. From flowering stage to fruit expanding stage, the response of fertilizer N was most activated. The nitrate reductase activity in leaves might be greatly affected by fertilizer N, while adequate Ca fertilization could decrease it. A combined application of N and Ca could promote the nitrate reductase activity. Both soil NO3(-)-N content and electric conductivity (EC) were increased with the increasing amount of applied fertilizer N.
 ...
PMID:[Interactive effect of N and Ca on N uptake by tomato]. 1533 67

The influence of different NH4+/NO3- ratios on nitrogen metabolism of cotton was studied under controlled hydroponics. The results showed that compared with single nitrate nutrition, solutions with 25/75, 50/50, 75/25 and 100/0 of NH4+/NO3- significantly increased the soluble protein accumulation in leaves and roots of cotton, and the maximum content of soluble protein in leaves and roots appeared respectively in the solution with 50/50 and 75/25 of NH4+/NO3-. The soluble protein content in roots was increased with the increase of NH4+ percentage, but was slightly less in the solution of 100/0 than 75/25, which was probably related to the excess NH4+ limiting boot metabolism. With the increase of NH4+ percentage, the nitrate content in petiole and the nitrate reductase activity in functional blade declined, but ammoniac nitrogen content increased in every organ of cotton. These results showed that foreign nitrogen affected the nitrogen metabolism of cotton in a different way, and the nitrogen absorption by cotton was probably related to different forms of foreign nitrogen.
 ...
PMID:[Influence of different NH4+/NO3- ratios on nitrogen metabolism of cotton]. 1533 79

The Central Asian Taklamakan desert is characterized by a hyperarid climate with less than 50 mm annual precipitation but a permanent shallow groundwater table. The perched groundwater (2-16 m) could present a reliable and constant source of nitrogen throughout the growing season and help overcome temporal nitrogen limitations that are common in arid environments. We investigated the importance of groundwater and nitrogen fixation in the nitrogen metabolism of desert plants by assessing the possible forms and availability of soil N and atmospheric N and the seasonal variation in concentration as well as isotopic composition of plant N. Water availability was experimentally modified in the desert foreland through simulated flooding to estimate the contribution of surface water and temporally increased soil moisture for nutrient uptake and plant-water relations. The natural vegetation of the Taklamakan desert is dominated by plants with high foliar nitrogen concentrations (2-3% DM) and leaf nitrate reductase activity (NRA) (0.2-1 micromol NO2- g(-1) FW h(-1)). There is little evidence that nitrogen is a limiting resource as all perennial plants exhibited fast rates of growth. The extremely dry soil conditions preclude all but minor contributions of soil N to total plant N so that groundwater is suggested as the dominant source of N with concentrations of 100 microM NO3-. Flood irrigation had little beneficial effect on nitrogen metabolism and growth, further confirming the dependence on groundwater. Nitrogen fixation was determined by the 15N natural abundance method and was a significant component of the N-requirement of the legume Alhagi, the average contribution of biologically fixed nitrogen in Alhagi was 54.8%. But nitrogen fixing plants had little ecological advantage owing to the more or less constant supply of N available from groundwater. From our data we conclude that the perennial species investigated have adapted to the environmental conditions through development of root systems that access groundwater to satisfy demands for both water and nutrients. This is an ecologically favourable strategy since only groundwater is a predictable and stable resource.
 ...
PMID:Nitrogen fixation and metabolism by groundwater-dependent perennial plants in a hyperarid desert. 1537 87

The influence of varying levels of salinity (0, 100, 200 and 400 mM) on the activities of nitrate reductase (NR, E.C. 1.6.6.1), acid phosphatase (ACP, E.C. 3.1.3.2), and alkaline phosphatase (ALP, EC 3.1.3.1 ) as well as on nitrate and phosphate uptake and total nitrogen levels in leaves of a true mangrove Bruguiera parviflora was investigated under hydroponic culture conditions. NR activity increased in 100mM NaCl treated plants, whereas it decreased gradually in 200 and 400 mM treated plants, relative to the controls. Decreased activity of NR by NaCl stress was also accompanied by a decrease in total nitrogen level and nitrate uptake. Decreases in NR activity, nitrate (NO3-), and total nitrogen level due to high salinity may be responsible for a decrease in growth and biomass production in this plant. However, salinity caused an increase in both ACP and ALP activity. Activity staining of ACP by native polyacrylamide gel electrophoresis revealed three isoforms: ACP-1, ACP-2, and ACP-3. We observed a preferential enhancement in the ACP-3 isoform by salinity. In order to understand whether the salinity-induced increase in phosphatase activity was due to inhibition in phosphate uptake, we monitored phosphate (Pi) levels in leaves and noted that phosphate levels decreased significantly under salinity. These results suggest that the induction of acid and ALP under salt stress may be due to a phosphorous deficiency.
 ...
PMID:Effects of NaCI stress on nitrogen and phosphorous metabolism in a true mangrove Bruguiera parviflora grown under hydroponic culture. 1538 3

Understanding of the influences of root-zone CO2 concentration on nitrogen (N) metabolism is limited. The influences of root-zone CO2 concentration on growth, N uptake, N metabolism and the partitioning of root assimilated 14C were determined in tomato (Lycopersicon esculentum). Root, but not leaf, nitrate reductase activity was increased in plants supplied with increased root-zone CO2. Root phosphoenolpyruvate carboxylase activity was lower with NO3(-)- than with NH4(+)-nutrition, and in the latter, was also suppressed by increased root-zone CO2. Increased growth rate in NO3(-)-fed plants with elevated root-zone CO2 concentrations was associated with transfer of root-derived organic acids to the shoot and conversion to carbohydrates. With NH4(+)-fed plants, growth and total N were not altered by elevated root-zone CO2 concentrations, although 14C partitioning to amino acid synthesis was increased. Effects of root-zone CO2 concentration on N uptake and metabolism over longer periods (> 1 d) were probably limited by feedback inhibition. Root-derived organic acids contributed to the carbon budget of the leaves through decarboxylation of the organic acids and photosynthetic refixation of released CO2.
 ...
PMID:The influence of root assimilated inorganic carbon on nitrogen acquisition/assimilation and carbon partitioning. 1572 Jun 30

The study showed that different ecological environment and cultivation system in various ecological regions of Zhejiang Province resulted in some different physiological characteristics of nitrogen nutrition and stress-resistance, especially in the aspect of NO3(-)-N and NH4+-N concentrations, between film-mulched and conventional flooded rice. Owing to the heat stress in Hangjiahu plain, the NO3(-)-N concentration of film-mulched rice decreased to some extent, but NH4+-N concentration increased markedly at tillering, jointing and booting stages, compared to conventional flooded rice. In Jinqu basin, the NO3(-)-N concentration of film-mulched rice at booting stage was higher, while the NH4+-N concentration in its roots was notably lower than those of conventional flooded rice, with NH4+-N concentration in its basal stems and leaves somewhat increased. Generally, the glutamine synthetase (GS) and nitrate reductase (NR) activities in film-mulched rice leaves were enhanced at booting stage, while malondiadehyde (MDA), soluble sugar (SS) and proline (Pro) concentrations had little changes. In conclusion, film-mulched cultivation was beneficial to the rice growth and its high yielding.
 ...
PMID:[Physiological characteristics of nitrogen nutrition and stress-resistance of film-mulched rice in various ecological regions of Zhejiang Province]. 1585 22

Kinetics of the oxygen atom transfer reactions [M(IV)(QC6H2-2,4,6-Pr(i)3)(S2C2Me2)2]1- + XO --> [M(VI)O(QC6H2-2,4,6-Pr(i)3)(S2C2Me2)2]1- + X in acetonitrile with substrates XO = NO3- and (CH2)4SO have been determined. The reactants are bis(dithiolene) complexes with M = Mo, W and sterically encumbered axial ligands with Q = O, S to stabilize mononuclear square pyramidal structures. The complex [MoIV(SC6H2-2,4,6-Pr(i)3)(S2C2Me2)2]1- is an analogue of the active site of dissimilatory nitrate reductase which in the reduced state contains a molybdenum atom bound by two pyranopterindithiolene ligands and a cysteinate residue. Nitrate reduction was studied with tungsten complexes because of unfavorable stability properties of the molybdenum complexes. Product nitrite was detected by a colorimetric method. All reactions with both substrates are second-order with associative transition states (deltaS approximately -20 eu). Variation of atoms M and Q, together with data from prior work, allows certain kinetics comparisons to be made. Among them, k2W/k2Mo = 25 for (CH2)4SO reduction (Q = S), an expression of the kinetic metal effect. Further, k2S/k2O = 28 and approximately 10(4) for nitrate and (CH2)4SO reduction, respectively, effects attributed to relatively more steric congestion in achieving the transition state with hindered phenolate vs thiolate ligands. The effect is more pronounced with the larger substrate. These results demonstrate the feasibility of tungsten-mediated nitrate reduction by direct atom transfer using molecules with both axial thiolate and phenolate ligands. Complexes of the type [M(IV)(OR)(S2C2Me2)2] are capable of reducing biological N-oxide, S-oxide, and nitrate substrates and thus constitute functional analogue reaction systems of enzymic transformations.
 ...
PMID:Reaction systems related to dissimilatory nitrate reductase: nitrate reduction mediated by bis(dithiolene)tungsten complexes. 1585 88

Excessive nitrate accumulated in plants affects vegetable quality severely and excessive nitrate ingestion would do harm to human health. Assimilatory NADH: nitrate reductase (NR, EC 1.6.6.1), a complex Mo-pterin-, cytochrome b(557)- and FAD-containing protein, catalyzes the regulated and rate-limiting step in the utilization of inorganic nitrogen by higher plants. Enhancing the activity of NR is conducive to reduce the concentration of nitrate in plants. The experiments were conducted to investigate the activity of nitrate reductase in different plant tissues and the relationship between external inducing solution concentration and NR activity (NRA) in plant leaves. Six plant seedlings growing in solution culture were deprived of an external nitrogen (N) supply for 2 weeks. On selected days, three of six plant seedlings were exposed to 50mmol/L NO3- for 0, 2, 5, 8, 11h, and four of the six plant seedlings were exposed to 0, 10, 30, 50mmol/L NO3- for 2h. The NRA was determined in vivo at 538nm using spectrophotometer. The results showed that NRA increased when those plant seedlings were induced by nitrate solution. The change trends of NRA in roots and in leaves of cole, pea and tomato were different during treating time. The NRA in cole leaves was higher than that in its root and in other two plants and increased along with inducing time, but the NRA in bea and tomato was highest when the treating time was 8h and 2h, respectively. The highest NRA in leaves of three kinds of Chinese cabbages and tomato was induced by different concentrations of KNO3 solution. In tomato leaves, the highest NRA was induced by 10 - 30mmol/L KNO3 solution. In three Chinese cabbages, Brassica chinensis L. cv. AJH, XBC and KR-605, the highest NRA was induced by 10, 30, 10mmol/L KNO3 solution, respectively. The results indicated that the response manners of NRA in plants to external nitrate solutions were different. According to these results, the level of NR mRNA in plants could be enhanced by nitrate inducement. The total RNA was isolated from tomato leaves and root which induced by 30mmol/L KNO3 solution for 2h, and NR cDNA was obtained by RT-PCR using the specific primers. The fragments of PCR products were cloned and sequenced. There are 2736 base pairs in the whole cDNA fragment. The deduced protein sequence contains 911 amino acids. The NR gene can be fused to the CaMV 35S promoter, then introduced to higher plants, such as vegetables. It is hoped to decrease drastically the nitrate content of the transgenic plants.
 ...
PMID:[Induced activity of nitrate reductase by nitrate and cloning of nitrate reductase gene]. 1596 98

Structural-functional analogue of the reduced site of dissimilatory nitrate reductase is synthesized as [Et4N][MoIV(SPh)(PPh3)(mnt)2].CH2Cl2 (1). PPh3 in 1 is readily dissociated in solution to generate the active site of the reduced site of dissimilatory nitrate reductase. This readily reacts with nitrate. The nitrate reducing system is characterized by substrate saturation kinetics. Oxotransfer to and from substrate has been coupled to produce a catalytic system, NO3- + PPh3 --> NO2- + OPPh3, where NO3- is the substrate for dissimilatory nitrate reductase. The corresponding chloro complex, [Et4N][MoIV(Cl)(PPh3)(mnt)2].CH2Cl2 (2), responds to similar PPh3 dissociation but is unable to react with nitrate, showing the indispensable role of thiolate coordination for such oxotransfer reaction. This investigation provides the initial demonstration of the ligand specificity in a model system similar to single point mutation involving site directed mutagenesis in this class of molybdoenzymes.
 ...
PMID:Chemistry of [Et4N][MoIV(SPh)(PPh3)(mnt)2] as an analogue of dissimilatory nitrate reductase with its inactivation on substitution of thiolate by chloride. 1656 72

Previous research showed that nano-TiO2 could significantly promote photosynthesis and greatly improve growth of spinach, but we also speculated that an increase of spinach growth by nano-TiO2 treatment might be closely related to the change of nitrogen metabolism. The effects of nanoanatase TiO2 on the nitrogen metabolism of growing spinach were studied by treating them with nano-anatase TiO2. The results showed that nano-anatase TiO2 treatment could obviously increase the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and glutamic-pyruvic transaminase during the growing stage. Nano-anatase TiO2 treatment could also promote spinach to absorb nitrate, accelerate inorganic nitrogen (such as NO3--N and NH4+-N) to be translated into organic nitrogen (such as protein and chlorophyll), and enhance the fresh weight and dry weights.
 ...
PMID:Influences of nano-anatase TiO2 on the nitrogen metabolism of growing spinach. 1675 45


<< Previous 1 2 3 4 5 6 7 8 9 10