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- Karlberg, L, et al.
(författare)
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Global Freshwater Resources
- 2009
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Ingår i: Fisheries, Sustainability and Development. - Stockholm : Royal Swedish Academy of Agriculture and Forestry. ; , s. 123-132, s. 123-132
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Tidskriftsartikel (refereegranskat)
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- Klemedtsson, Leif, 1953, et al.
(författare)
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Bayesian calibration method used to elucidate carbon turnover in forest on drained organic soil
- 2008
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 89:1, s. 61-79
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Tidskriftsartikel (refereegranskat)abstract
- Depending on the balance between sink and source processes for C, drained organic forest soil ecosystems can be in balance or act as net sinks or sources of CO2 to the atmosphere. In order to study the effect of groundwater level and soil temperature on C-flux, the CoupModel was calibrated (climate data, groundwater levels, soil CO2 flux, net ecosystem fluxes of CO2-exchange, sensible heat flux and latent heat flux, forest production etc.) for a drained forest in Sweden. Bayesian calibration techniques were used to elucidate how different parameters and variables were interlinked in C-circulation. The calibrated model reproduced abiotic and biotic variables reasonably well except for root respiration, which was largely underestimated. Bayesian calibration reduced the uncertainties in the model and highlighted the fact that calibrations should be performed with a high number of parameters instead of specific parameter values.
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- Krajewski, Wojciech W., et al.
(författare)
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Crystal Structures of Mammalian Glutamine Synthetases Illustrate Substrate-Induced Conformational Changes and Provide Opportunities for Drug and Herbicide Design
- 2008
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 375:1, s. 217-228
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Tidskriftsartikel (refereegranskat)abstract
- Glutamine synthetase (GS) catalyzes the ligation of glutamate and ammonia to form glutamine, with concomitant hydrolysis of ATP. In mammals, the activity eliminates cytotoxic ammonia, at the same time converting neurotoxic glutamate to harmless glutamine; there are a number of links between changes in GS activity and neurodegenerative disorders, such as Alzheimer's disease. In plants, because of its importance in the assimilation and re-assimilation of ammonia, the enzyme is a target of some herbicides. GS is also a central component of bacterial nitrogen metabolism and a potential drug target. Previous studies had investigated the structures of bacterial and plant GSs. In the present publication, we report the first structures of mammalian GSs. The apo form of the canine enzyme was solved by molecular replacement and refined at a resolution of 3 Å. Two structures of human glutamine synthetase represent complexes with: a) phosphate, ADP, and manganese, and b) a phosphorylated form of the inhibitor methionine sulfoximine, ADP and manganese; these structures were refined to resolutions of 2.05 Å and 2.6 Å, respectively. Loop movements near the active site generate more closed forms of the eukaryotic enzymes when substrates are bound; the largest changes are associated with the binding of the nucleotide. Comparisons with earlier structures provide a basis for the design of drugs that are specifically directed at either human or bacterial enzymes. The site of binding the amino acid substrate is highly conserved in bacterial and eukaryotic GSs, whereas the nucleotide binding site varies to a much larger degree. Thus, the latter site offers the best target for specific drug design. Differences between mammalian and plant enzymes are much more subtle, suggesting that herbicides targeting GS must be designed with caution.
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