| 1. |
- Carlsson, Peter, et al.
(författare)
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Bacillus subtilis citM, the structural gene for dihydrolipoamide transsuccinylase: cloning and expression in Escherichia coli
- 1987
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Ingår i: Gene. - : Elsevier BV. - 1879-0038 .- 0378-1119. ; 61:2, s. 217-224
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Tidskriftsartikel (refereegranskat)abstract
- The 2-oxoglutarate dehydrogenase multienzyme complex is composed of three different subenzymes: 2-oxoglutarate dehydrogenase (E1o), dihydrolipoamide transsuccinylase (E2o), and dihydrolipoamide dehydrogenase (E3). Bacillus subtilis E1o and E2o are encoded by the citK and citM genes, respectively. A 3.4-kb BamHI DNA fragment containing citK and citM markers was isolated from a library of B. subtilis DNA in Escherichia coli. Functional E2o was expressed from the cloned DNA both in B. subtilis and E. coli. E2o had an apparent Mr of 60000 when expressed in E. coli. The B. subtilis E2o component complemented an E. coli E2o-defective mutant in vivo and in vitro. It is concluded that functional B. subtilis E2o can be produced in E. coli and can interact with E. coli and E1o and E3 to form an active chimeric enzyme complex.
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| 2. |
- Altman, S, et al.
(författare)
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Catalysis by the RNA subunit of RNase P
- 1989
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Ingår i: Gene. - : Elsevier BV. - 0378-1119 .- 1879-0038. ; 82:1, s. 63-64
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Forskningsöversikt (refereegranskat)abstract
- RNase P, an enzyme that contains both RNA and protein components, cleaves tRNA precursors to generate mature 5' termini. The catalytic activity of RNase P resides in the RNA component, with the protein cofactor affecting the rate of the cleavage reaction. The reaction is also influenced by the nature of the tRNA substrate.
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| 3. |
- Bartilson, M, et al.
(författare)
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Nucleotide sequence and expression of the catechol 2,3-dioxygenase-encoding gene of phenol-catabolizing Pseudomonas CF600.
- 1989
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Ingår i: Gene. - 0378-1119 .- 1879-0038. ; 85:1
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Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas CF600 degrades phenol and some of its methylated derivatives via a plasmid-encoded catabolic pathway. The catechol 2,3-dioxygenase (C23O) enzyme of this pathway catalyses the conversion of catechol to 2-hydroxymuconic semialdehyde. We have determined the nucleotide (nt) sequence of the dmpB structural gene for this enzyme, and expressed and identified its polypeptide product in Escherichia coli. The xylE gene of TOL plasmid pWWO and the nahH gene of plasmid NAH7 encode analogous C23O enzymes. Comparison of these three genes shows homology of 78-81% on the nt level and 83-87% homology on the amino acid level.
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| 4. |
- Andersson, Göran, et al.
(författare)
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Pressure dependence of the c-axis resistance of stage 2 SbCl5 intercalated graphite to 4 GPa
- 1988
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 65:7, s. 735-738
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Tidskriftsartikel (refereegranskat)abstract
- The c-axis electrical resistance R has been measured under pressure up to 4 GPa (40 kbar) at room temperature for stage 2, HOPG-based SbCl5 intercalated graphite. In addition to the well known ordering transition at 0.3–0.5 GPa a second anomaly in R is observed above 1 GPa, corresponding to a further phase transition which is not completed until above 2.4 GPa. In all phases R depends more strongly on p for the intercalated material than for HOPG, and the total decrease in R is over 80% to 4 GPa.
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| 5. |
- Bonde, Torben A., et al.
(författare)
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Microbial biomass as a fraction of potentially mineralizable nitrogen in soils from long-term field experiments
- 1988
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 20:4, s. 447-452
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Tidskriftsartikel (refereegranskat)abstract
- Aerobic long-term incubations (40-wk) were employed to measure the potentially mineralizable nitrogen (N0) in five 30-yr old cropping systems. The cropping systems consisted of: (1) bare fallow; (2) cropping with no additions; (3) cropping with 80 kg N ha-1 y-1 as Ca(NO3)2; (4) cropping with 80 kg N ha-1 yr-1 as Ca(NO3)2 plus 1800kg C ha-1 yr-1 as straw; and (5) cropping with 80 kg N ha-1 yr-1 plus 1800 kg C ha-1 yr-1 as farmyard manure. The amounts of N mineralized during the 40-wk incubations were between 93 and 168 μg g-1 (302-543 kg N ha-1 down to 25cm depth) with the lowest value for the fallow and the highest for the farmyard manure treatment. Microbial biomass-C and -N were measured on four occasions during the incubations. The biomass-C showed a rapid decrease to week 4 (to 36% of the initial mass), a slower decrease to week 9 (to 23% of initial mass) and a very slow decline to the final determination at the end of the incubation (to 8% of initial mass). The biomass-N displayed a similar pattern. Two related models were employed to describe the kinetics of N-mineralization during incubation: (1) a two-component first-order; and (2) a simplified special case of the two-component model. In all cases except the straw-amended soil, the simplified two-component model offered the best description of the curves of accumulated mineral-N. The available fraction, Na, of soil organic-N had mineralization rate constants similar to those for mineralization of microbial biomass.
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| 6. |
- Karlsson, Krister, 1961-, et al.
(författare)
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Theoretical investigation of energy shifts at the GaAs/Au interface
- 1988
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Ingår i: Solid State Communications. - : Elsevier. - 0038-1098 .- 1879-2766. ; 67:4, s. 339-342
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Tidskriftsartikel (refereegranskat)abstract
- We have used an image screening model to calculate the shift of the Ga(3d−1) core-level distribution when a GaAs surface is covered with metal. Using the GaAs bulk dielectric constant we find a shift of 0.1 (0.18) eV with a mean free path of 25 (8) Å. These shifts are comparable to the measured ones,1 indicating that final-state (image) screening represents an important part of core-level shifts in the vicinity of the interface.
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| 7. |
- KARLSSON, Ulf O, et al.
(författare)
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INTRINSIC SURFACE-STATE ON BE(0001)
- 1984
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098 .- 1879-2766. ; 49:7, s. 711-714
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Klemendtsson, Leif, et al.
(författare)
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Microbial nitrogen transformations in the root environment of barley
- 1987
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 19:5, s. 551-558
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Tidskriftsartikel (refereegranskat)abstract
- To determine the influence of barley roots on microorganisms and N-transfonning processes in soil, numbers of nitrifiers and potential nitrification and denitrification rates were measured every week for 5 wks. The barley plants were grown in growth chambers in which the root-containing soil layer (A) was separated from three outer soil layers (B, C, D). The numbers and biomass of bacteria, numbers of flagellates and amoebae, total and FDA-active hyphal lengths, microbial biomass carbon and respiration were also determined.The numbers of ammonium oxidizers were positively correlated with root biomass but did not differ significantly between soil layers. Potential ammonium oxidation was stimulated in the root-layer, while potential nitrite oxidation was stimulated in the B- and C-layers.The denitrification activity (measured anaerobically in the presence of excess No- 3) was positively correlated with root biomass in the A-layer. Denitrification activity in the B-layer was positively correlated with the water content of the soil. When roots grew near the nets separating the root layer from the other layers, denitrification activity was stimulated in the next layer (B).We propose that nitrite oxidation in the root zone partly depends on the reduction of nitrate. This would explain why nitrite-oxidizer numbers were usually several orders of magnitude higher than ammonium-oxidizer numbers.Bacterial numbers decreased between wks 1 and 5. Increases in bacteria, naked amoebae and flagellates in all layers between wks 2 and 3 indicated that bacteria were produced until wk 3. There were no signs of bacterial production after wk 3.The total length of hyphae and the length of FDA-active hyphae were not significantly different between layers. However, both of these parameters, as well as total microbial biomass carbon and respiration, were consistently highest in the A-layer.
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| 9. |
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| 10. |
- Lundberg, Bo, et al.
(författare)
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Basal plane resistivity and phase diagram of HNO3 intercalated graphite in the range 130–320 K and 0–1.6 GPa
- 1986
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Ingår i: Solid State Communications. - : Elsevier Science Ltd.. - 0038-1098 .- 1879-2766. ; 58:10, s. 747-751
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Tidskriftsartikel (refereegranskat)abstract
- The basal plane resistivity varrho of stages 3–5 HNO3 intercalated graphite has been measured as a function of temperature T and pressure p in the range 130–320 K and 0–1.6 GPa (16 kbar). A contactless method was used. The phase boundary of the 250 K ordering transition at zero pressure was traced up to 320 K through the corresponding anomaly in varrho. The pressure dependence of varrho was strongly stage dependent, such that for stages 3, 4 and 5 the observed pressure coefficients (1/varrho)dvarrho/dp were approximately 0.08, −0.08, and −0.22 GPa−1, respectively, near zero pressure.
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