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101.
Residence time and kinetic efficiency analysis of extracellular signal-regulated kinase 2 inhibitors
Darin Vanderpool Charles E. Grimshaw J. David Lawson Jacques Ermolieff 《Analytical biochemistry》2015
The RAS/RAF/MEK/ERK signal transduction cascade plays an important role in the regulation of critical cellular processes such as cell proliferation, migration, and differentiation. The up-regulation of this pathway can negatively affect cell homeostasis and is responsible for the development of various forms of cancer and inflammation processes. Therefore, there is a strong interest in pursuing drug programs targeting some of the enzymes involved in this pathway. In addition to the determination of Ki, Kd, IC50, and/or EC50, a more thorough kinetic analysis can provide useful information for the selection of the best lead series during the early stage of the drug discovery process. This study describes a medium-throughput fluorescent probe displacement assay for the rapid determination of the koff constant, residence time, and kinetic efficiency for ERK (extracellular signal-regulated kinase) inhibitors. Using this method, we have identified several inhibitors that we have subjected to further kinetic analysis by comparing koff constants determined for these time-dependent inhibitors using either the active or inactive form of ERK2. 相似文献
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Jian Jin Dominic Lauricella Roger Armstrong Peter Sale Caixian Tang 《Annals of botany》2015,116(6):975-985
Background and Aims Benefits to crop productivity arising from increasing CO2 fertilization may be offset by detrimental effects of global climate change, such as an increasing frequency of drought. Phosphorus (P) nutrition plays an important role in crop responses to water stress, but how elevated CO2 (eCO2) and P nutrition interact, especially in legumes, is unclear. This study aimed to elucidate whether P supply improves plant drought tolerance under eCO2.Methods A soil-column experiment was conducted in a free air CO2 enrichment (SoilFACE) system. Field pea (Pisum sativum) was grown in a P-deficient vertisol, supplied with 15 mg P kg−1 (deficient) or 60 mg P kg−1 (adequate for crop growth) and exposed to ambient CO2 (aCO2; 380–400 ppm) or eCO2 (550–580 ppm). Drought treatments commenced at flowering. Measurements were taken of soil and leaf water content, photosynthesis, stomatal conductance, total soluble sugars and inorganic P content (Pi).Key Results Water-use efficiency was greatest under eCO2 when the plants were supplied with adequate P compared with other treatments irrespective of drought treatment. Elevated CO2 decreased stomatal conductance and transpiration rate, and increased the concentration of soluble sugars and relative water contents in leaves. Adequate P supply increased concentrations of soluble sugars and Pi in drought-stressed plants. Adequate P supply but not eCO2 increased root length distribution in deeper soil layers.Conclusions Phosphorus application and eCO2 interactively enhanced periodic drought tolerance in field pea as a result of decreased stomatal conductance, deeper rooting and high Pi availability for carbon assimilation in leaves. 相似文献
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The impact of elevated carbon dioxide on the phosphorus nutrition of plants: a review 总被引:1,自引:0,他引:1
Background Increasing attention is being focused on the influence of rapid increases in atmospheric CO2 concentration on nutrient cycling in ecosystems. An understanding of how elevated CO2 affects plant utilization and acquisition of phosphorus (P) will be critical for P management to maintain ecosystem sustainability in P-deficient regions.Scope This review focuses on the impact of elevated CO2 on plant P demand, utilization in plants and P acquisition from soil. Several knowledge gaps on elevated CO2-P associations are highlighted.Conclusions Significant increases in P demand by plants are likely to happen under elevated CO2 due to the stimulation of photosynthesis, and subsequent growth responses. Elevated CO2 alters P acquisition through changes in root morphology and increases in rooting depth. Moreover, the quantity and composition of root exudates are likely to change under elevated CO2, due to the changes in carbon fluxes along the glycolytic pathway and the tricarboxylic acid cycle. As a consequence, these root exudates may lead to P mobilization by the chelation of P from sparingly soluble P complexes, by the alteration of the biochemical environment and by changes to microbial activity in the rhizosphere. Future research on chemical, molecular, microbiological and physiological aspects is needed to improve understanding of how elevated CO2 might affect the use and acquisition of P by plants. 相似文献
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SHULI NIU XUERONG XING ZHE ZHANG JIANYANG XIA XUHUI ZHOU BING SONG LINGHAO LI SHIQIANG WAN 《Global Change Biology》2011,17(2):1073-1082
Water‐use efficiency (WUE) has been recognized as an important characteristic of ecosystem productivity, which links carbon (C) and water cycling. However, little is known about how WUE responds to climate change at different scales. Here, we investigated WUE at leaf, canopy, and ecosystem levels under increased precipitation and warming from 2005 to 2008 in a temperate steppe in Northern China. We measured gross ecosystem productivity (GEP), net ecosystem CO2 exchange (NEE), evapotranspiration (ET), evaporation (E), canopy transpiration (Tc), as well as leaf photosynthesis (Pmax) and transpiration (Tl) of a dominant species to calculate canopy WUE (WUEc=GEP/T), ecosystem WUE (WUEgep=GEP/ET or WUEnee=NEE/ET) and leaf WUE (WUEl=Pmax/Tl). The results showed that increased precipitation stimulated WUEc, WUEgep and WUEnee by 17.1%, 10.2% and 12.6%, respectively, but decreased WUEl by 27.4%. Climate warming reduced canopy and ecosystem WUE over the 4 years but did not affect leaf level WUE. Across the 4 years and the measured plots, canopy and ecosystem WUE linearly increased, but leaf level WUE of the dominant species linearly decreased with increasing precipitation. The differential responses of canopy/ecosystem WUE and leaf WUE to climate change suggest that caution should be taken when upscaling WUE from leaf to larger scales. Our findings will also facilitate mechanistic understanding of the C–water relationships across different organism levels and in projecting the effects of climate warming and shifting precipitation regimes on productivity in arid and semiarid ecosystems. 相似文献
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Kristian R. Albert Teis N. MikkelsenHelge Ro-Poulsen Marie F. ArndalAnders Michelsen 《Environmental and Experimental Botany》2011,72(3):439-447
Ambient ultraviolet-B (UV-B) radiation potentially impacts the photosynthetic performance of high Arctic plants. We conducted an UV-B exclusion experiment in a dwarf shrub heath in NE Greenland (74°N), with open control, filter control, UV-B filtering and UV-AB filtering, all in combination with leaf angle control. Two sites with natural leaf positions had ground angles of 0° (‘level site’) and 45° (‘sloping site’), while at a third site the leaves were fixed in an angle of 45° to homogenize the irradiance dose (‘fixed leaf angle site’). The photosynthetic performance of the leaves was characterized by simultaneous gas exchange and chlorophyll fluorescence measurements and the PSII performance through the growing season was investigated with fluorescence measurements. Leaf harvest towards the end of the growing season was done to determine the specific leaf area and the content of carbon, nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate of electron transport (Jmax) and the maximum carboxylation rate of Rubisco (Vcmax), and the PSII performance showed a decreased quantum yield and increased energy dissipation. A parallel response pattern and reduced PSII performance at all three sites indicate that these responses take place in all leaves across position in the vegetation. These findings add to the evidence that the ambient solar UV-B currently is a significant stress factor for plants in high Arctic Greenland. 相似文献