| 71. |
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| 72. |
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| 73. |
- Hederstedt, Lars, et al.
(författare)
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Processing of Bacillus subtilis succinate dehydrogenase and cytochrome b-558 polypeptides
- 1987
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 213, s. 385-390
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Tidskriftsartikel (refereegranskat)abstract
- The DNA sequence of the Bacillus subtilis sdh operon coding for the two succinate dehydrogenase subunits and cytochrome b-558 (the membrane anchor protein) has recently been established. We have now determined the extent of N-terminal processing of each polypeptide by radiosequence analysis. At the same time, direct evidence for the correctness of the predicted reading frames has been obtained. The cytochrome showed a ragged N-terminus, with forms lacking one residue, and is inserted across the membrane without an N-terminal leader-peptide. Covalently bound flavin was not detectable in B. subtilis succinate dehydrogenase expressed in Escherichia coli despite normal N-terminal processing of the apoprotein. This provides an explanation to why the succinate dehydrogenase synthesized in E. coli is not functional and demonstrates that host-specific factors regulate the coenzyme attachment.
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| 74. |
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| 75. |
- Hulst, A C, et al.
(författare)
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Immobilized Plant Cells: Respiration and Oxygen Transfer
- 1985
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Ingår i: Journal of chemical technology and biotechnology (1986). - : Wiley. - 0268-2575 .- 1097-4660 .- 0264-3421 .- 1935-1828. ; 35:3, s. 198-204
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Tidskriftsartikel (refereegranskat)abstract
- The influence of support material (calcium alginate, x-carrageenan and agarose), cell loading and, in case of alginate, bead diameter on the rate of respiration of immobilised plant cells (Daucus carota) was investigated. No significant differences were observed between the three supports and no loss of respiration activity occurred as result of immobilisation per se. The results show further that above a critical combination of cell loading and bead diameter limitations of the rate of respiration by diffusion of oxygen increases with increasing loading and diameter.
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| 76. |
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| 77. |
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| 78. |
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| 79. |
- Jeppsson, Jan olof, et al.
(författare)
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Isolation and characterization of two minor fractions of α1,-antitrypsin by high-performance liquid chromatographic chromatofocusing
- 1985
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 327, s. 173-177
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Tidskriftsartikel (refereegranskat)abstract
- α1-Antitrypsin is a glycoprotein that separates into five electrophoretic fractions, viz. M2, M4, M6, M7 and M8. Con A-Sepharose separates the protein into three fractions according to the branching degree of the three oligosaccharide chains. The Con A affinity is identical for M4 and M7 and for M6 and M8. Within each pair the proteins were isolated by rapid chromatofocusing. The M7 and M8 have the same carbohydrate structure as the major M4 and M6 respectively, but have lost the first five N-terminal amino acids (Glu-Asp-Pro-Glu-Gly) as compared to the majority of the protein.
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| 80. |
- Jonsson, Mats, 1939, et al.
(författare)
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Orientation of DNA during gel electrophoresis studied with linear dichroism spectroscopy
- 1988
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 27:3, s. 381-414
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Tidskriftsartikel (refereegranskat)abstract
- A method for in situ study of orientation of DNA during gel electrophoresis has been developed. Linear dichroism spectra measured by this phase-modulation technique can sensitively and selectively detect orientation of DNA during electrophoretic migration in gel. [Measurement of “electrophoretic orientation” was first reported in 1985 by B. Åkerman, M. Jonsson, and B. Nordén (1985) (J. Chem. Soc. Chem. Commun. 422–423)]. Restriction fragments of duplex DNA of lengths in the ranges of 300–2319 base pairs (bp) and 4361–23130 bp have been studied in 5% polyacrylamide and 1% agarose gels, respectively. The fragments become preferentially oriented with the DNA helix axis parallel to the migration direction. In agarose the orientation is found to increase sigmoidally, and in polyacrylamide, linearly, with the electric field strength, within the field ranges accessible to measurement (0–40 and 5–40 V/cm, respectively). In both types of gels a considerable increase in orientation with length of DNA was observed. Compared to dipole orientation in electric fields, the electrophoretic orientation is high: orientation factor S = 0.027 in agarose for 23130 bp at 10 V/cm and S = 0.004 in polyacrylamide for 2319 bp at 10 V/cm. In addition to orientation of DNA, the electrophoresis also leads to orientation effects in the gel structure owing to Joule heating. In agarose there is also an effect that is associated with the migrating DNA zones and that produces different orientations of the gel at the front and rear parts of a zone. Evidence is presented that this effect is due to a DNA-induced electroosmotic flow causing a contraction of the gel in the front of the zone and an expansion in the rear. The experimental results on DNA orientation are compared with the reptation theories for gel electrophoresis. The theory of Lumpkin et al. [O. J. Lumpkin, P. Dejardin, and B. H. Zimm (1985) Biopolymers24, 1573–1593] predicts no orientation length dependence, but it does predict a shape of the field dependence that resembles the shape observed in agarose. The theory of Slater and Noolandi [G. W. Slater and J. Noolandi (1986) Biopolymers25, 431–454] predicts an orientational length dependence that is an order of magnitude less than the experimental one, and a field dependence that agrees neither with the sigmoidal shape observed in agarose nor with the linear dependence in polyacrylamide.
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