| 51. |
- Hederstedt, Lars, et al.
(författare)
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New properties of Bacillus subtilis succinate dehydrogenase altered at the active site
- 1989
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Ingår i: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 260:2, s. 491-497
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian and Escherichia coli succinate dehydrogenase (SDH) and E. coli fumarate reductase apparentlycontain an essential cysteine residue at the active site, as shown by substrate-protectable inactivation withthiol-specific reagents. Bacillus subtilis SDH was found to be resistant to this type of reagent and containsan alanine residue at the amino acid position equivalent to the only invariant cysteine in the flavoproteinsubunit of E. coli succinate oxidoreductases. Substitution of this alanine, at position 252 in the flavoprotein subunit of B. subtilis SDH, by cysteine resulted in an enzyme sensitive to thiol-specific reagents and protectable by substrate. Other biochemical properties of the redesigned SDH were similar to those of the wild-type enzyme. It is concluded that the invariant cysteine in the flavoprotein of E. coli succinate oxidoreductases corresponds to the active site thiol. However, this cysteine is most likely not essential for succinate oxidation and seemingly lacks an assignable specific function. An invariant arginine in juxtaposition to Ala-252 in the flavoprotein of B. subtilis SDH, and to the invariant cysteine in the E. coli homologous enzymes, is probably essential for substrate binding.
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| 52. |
- Hedling, Olof, et al.
(författare)
-
Train Kept a Rollin' : Antonioni, Blow Up och den brittiska bluesvågen
- 2008
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Ingår i: Theorier om verklig diktning. - : Absalon förlag, Lund. ; 25, s. 349-358
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Discussion and presentation of the extraordinary outpour of blues music and blues musicians out of Britain in the 1960s and how this is briefly portrayed in Michelangelo Antonioni's film Blow Up (1966).
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| 53. |
- Hessler, Martin, 1978-
(författare)
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Optimization, Matroids and Error-Correcting Codes
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first subject we investigate in this thesis deals with optimization problems on graphs. The edges are given costs defined by the values of independent exponential random variables. We show how to calculate some or all moments of the distributions of the costs of some optimization problems on graphs.The second subject that we investigate is 1-error correcting perfect binary codes, perfect codes for short. In most work about perfect codes, two codes are considered equivalent if there is an isometric mapping between them. We call this isometric equivalence. Another type of equivalence is given if two codes can be mapped on each other using a non-singular linear map. We call this linear equivalence. A third type of equivalence is given if two codes can be mapped on each other using a composition of an isometric map and a non-singular linear map. We call this extended equivalence.In Paper 1 we give a new better bound on how much the cost of the matching problem with exponential edge costs varies from its mean.In Paper 2 we calculate the expected cost of an LP-relaxed version of the matching problem where some edges are given zero cost. A special case is when the vertices with probability 1 – p have a zero cost loop, for this problem we prove that the expected cost is given by a formula.In Paper 3 we define the polymatroid assignment problem and give a formula for calculating all moments of its cost.In Paper 4 we present a computer enumeration of the 197 isometric equivalence classes of the perfect codes of length 31 of rank 27 and with a kernel of dimension 24.In Paper 5 we investigate when it is possible to map two perfect codes on each other using a non-singular linear map.In Paper 6 we give an invariant for the equivalence classes of all perfect codes of all lengths when linear equivalence is considered.In Paper 7 we give an invariant for the equivalence classes of all perfect codes of all lengths when extended equivalence is considered.In Paper 8 we define a class of perfect codes that we call FRH-codes. It is shown that each FRH-code is linearly equivalent to a so called Phelps code and that this class contains Phelps codes as a proper subset.
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| 54. |
- Janson, Håkan, et al.
(författare)
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Protein D, an immunoglobulin D-binding protein of Haemophilus influenzae: cloning, nucleotide sequence, and expression in Escherichia coli
- 1991
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Ingår i: Infection and Immunity. - 1098-5522. ; 59:1, s. 119-125
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Tidskriftsartikel (refereegranskat)abstract
- The gene for protein D, a membrane-associated protein with specific affinity for human immunoglobulin D, was cloned from a nontypeable strain of Haemophilus influenzae. The gene was expressed in Escherichia coli from an endogenous promoter, and the gene product has an apparent molecular weight equal to that of H. influenzae protein D (42,000). The complete nucleotide sequence of the gene for protein D was determined, and the deduced amino acid sequence of 364 residues includes a putative signal sequence of 18 amino acids containing a consensus sequence, Leu-Ala-Gly-Cys, for bacterial lipoproteins. The sequence of protein D shows no similarity to those of other immunoglobulin-binding proteins. Protein D is the first example of immunoglobulin receptors from gram-negative bacteria that has been cloned and sequenced.
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| 55. |
- Lehmann, Juliane, et al.
(författare)
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Some necessary conditions for vector space partitions
- 2012
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Ingår i: Discrete Mathematics. - : Elsevier BV. - 0012-365X .- 1872-681X. ; 312:2, s. 351-361
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Tidskriftsartikel (refereegranskat)abstract
- Some new necessary conditions for the existence of vector space partitions are derived. They are applied to the problem of finding the maximum number of spaces of dimension t in a vector space partition of V(2t, q) that contains m(d) spaces of dimension d, where t/2 < d < t, and also spaces of other dimensions. It is also discussed how this problem is related to maximal partial t-spreads in V (2t, q). We also give a lower bound for the number of spaces in a vector space partition and verify that this bound is tight.
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| 56. |
- Rosén, Stefan, et al.
(författare)
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Molecular characterization of a saline-soluble lectin from a parasitic fungus : Extensive sequence similarities between fungal lectins
- 1996
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 238:3, s. 822-829
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that the interactions between several parasite and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene displayed an extensive similarity (identity 46.3%) to that of a gene encoding a lectin (ABL) recently isolated from the mushroom Agaricus bisporus (basidiomycete), but not to any other fungal, microbial, plant, or animal lectins. The similarities between AOL and ABL were further demonstrated by the observation that an antibody specific for AOL cross-reacted with ABL. Together with data showing that AOL has a binding specificity that is similar to that of ABL [Rosen, S., Bergstrom, J., Karlsson, K.-A., and Tunlid, A. (1996) Eur. J. Biochem. 238, 830-837], these results indicate that AOL and ABL are members of a novel family of saline- soluble lectins present in fungi. Southern blots indicated that there is only one AOL gene in the genome encoding a subunit (monomer) of the lectin. The primary structure of AOL did not show the presence of a typical N-terminal signal sequence. Comparison of the deduced primary structure with the molecular mass of AOL as determined by electrospray mass spectrometry (16153 Da), indicated that AOL has an acetylated N-terminal but no other post- translational modifications, and that a minor isoform is formed by deamidation. Circular dichroism (CD) spectroscopy suggested that the secondary structure of AOl contains 34% β-sheets, 21% α-helix, and 45% turns and coils.
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| 57. |
- Westerbäck, Thomas
(författare)
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Parity check systems, perfect codes and codes over Frobenius rings
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of five papers related to coding theory. The first four papers are mainly devoted to perfect 1-error correcting binary codes. The fifth paper concerns codes over finite Abelian groups and finite commutative Frobenius rings. In Paper A we construct a new class of perfect binary codes of length 15. These codes can not be obtained by a construction of Phelps and Solov’eva. The verification of the existence of these kind of codes gives an answer to a question by Zinoviev and Zinoviev from 2003. In Paper B the concept of extended equivalence for binary codes is introduced. A linear code L*C, which is an invariant for this equivalence relation, is associated with every perfect binary code C. By using L*C we give, in some particular cases, a complete enumeration of the extended equivalence classes of perfect binary codes. In Paper C and D we prove that there exist perfect binary codes and extended perfect binary codes with a trivial symmetry group for most admissible cases of lengths and ranks. The results of these two papers have, together with previously known results, completely solved the problem of for which lengths and ranks there exist perfect binary codes with a trivial symmetry group, except in a handful of cases. In Paper E the concept of parity check matrices of linear codes over finite fields is generalized to parity check systems of both linear and nonlinear codes over finite Abelian groups and finite commutative Frobenius rings. A parity check system is a concatenation of two matrices and can be found by the use of Fourier analysis over finite Abelian groups. It is shown how some fundamental properties of a code can be derived from the set of columns or the set of rows in an associated parity check system. Furthermore, in Paper E, Cayley graphs and integral group rings are associated with parity check systems in order to investigate some problems in coding theory.
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