| 1. |
- Areschoug, Thomas, et al.
(författare)
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A Proline-Rich Region with a Highly Periodic Sequence in Streptococcal beta Protein Adopts the Polyproline II Structure and Is Exposed on the Bacterial Surface.
- 2002
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 184:22, s. 6376-6383
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Tidskriftsartikel (refereegranskat)abstract
- Proline-rich regions have been identified in many surface proteins of pathogenic streptococci and staphylococci. These regions have been suggested to be located in cell wall-spanning domains and/or to be required for surface expression of the protein. Because little is known about these regions, which are found in extensively studied and biologically important surface proteins, we characterized the proline-rich region in one such protein, the beta protein of group B streptococci. The proline-rich region in beta, designated the XPZ region, has a proline at every third position, and the sequence is highly periodic in other respects. Immunochemical analysis showed that the XPZ region was not associated with the cell wall but was exposed on the bacterial surface. Moreover, characterization of a beta mutant lacking the XPZ region demonstrated that this region was not required for surface expression of the beta protein. Comparison of the XPZ region in different beta proteins showed that it varied in size but always retained the typical sequence periodicity. Circular dichroism spectroscopy indicated that the XPZ region had the structure of a polyproline II helix, an extended and solvent-exposed structure with exactly three residues per turn. Because of the three-residue sequence periodicity in the XPZ region, it is expected to be amphipathic and to have distinct nonpolar and polar surfaces. This study identified a proline-rich structure with unique properties that is exposed on the surface of an important human pathogen.
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| 2. |
- Avgustinovich, S. V., et al.
(författare)
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On intersection problem for perfect binary codes
- 2006
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Ingår i: Designs, Codes and Cryptography. - : Springer Science and Business Media LLC. - 0925-1022 .- 1573-7586. ; 39:3, s. 317-322
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Tidskriftsartikel (refereegranskat)abstract
- The main result is that to any even integer q in the interval 0 <= q <= 2(n+1-2) (log(n+1)), there are two perfect codes C-1 and C-2 of length n = 2(m) -1, m >= 4, such that vertical bar C-1 boolean AND C-2 vertical bar = q.
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| 3. |
- Avgustinovich, S. V., et al.
(författare)
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On partitions of an n-cube into nonequivalent perfect codes
- 2007
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Ingår i: Problems of Information Transmission. - : Pleiades Publishing Ltd. - 0032-9460 .- 1608-3253. ; 43:4, s. 310-315
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Tidskriftsartikel (refereegranskat)abstract
- We prove that for all n = 2(k)-1, k >= 5. there exists a partition of the set of all binary vectors of length n into pairwise nonequivalent perfect binary codes of length n with distance 3.
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| 4. |
- Avgustinovich, S. V., et al.
(författare)
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On the structure of symmetry groups of Vasil'ev codes
- 2005
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Ingår i: Problems of Information Transmission. - : Springer Science and Business Media LLC. - 0032-9460 .- 1608-3253. ; 41:2, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- The structure of symmetry groups of Vasil'ev codes is studied. It is proved that the symmetry group of an arbitrary perfect binary non-full-rank Vasil'ev code of length n is always nontrivial; for codes of rank n - log(n + 1) + 1, an attainable upper bound on the order of the symmetry group is obtained.
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| 5. |
- Avgustinovich, S. V., et al.
(författare)
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The classification of some perfect codes
- 2004
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Ingår i: Designs, Codes and Cryptography. - 0925-1022 .- 1573-7586. ; 31:3, s. 313-318
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Tidskriftsartikel (refereegranskat)abstract
- Perfect 1-error correcting codes C in Z(2)(n), where n = 2(m) - 1, are considered. Let [C] denote the linear span of the words of C and let the rank of C be the dimension of the vector space [C]. It is shown that if the rank of C is n - m + 2 then C is equivalent to a code given by a construction of Phelps. These codes are, in case of rank n - m + 2, described by a Hamming code H and a set of MDS-codes D-h; h is an element of H, over an alphabet with four symbols. The case of rank n - m + 1 is much simpler: Any such code is a Vasil'ev code.
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| 6. |
- De Lucca, Anthony J., et al.
(författare)
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Antifungal Properties of Wheat Histones (H1-H4) and Purified Wheat Histone H1
- 2011
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 59:13, s. 6933-6939
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Tidskriftsartikel (refereegranskat)abstract
- Wheat (Triticum spp.) histones H1, H2, H3, and H4 were extracted, and H1 was further purified. The effect of these histones on specific fungi that may or may not be pathogenic to wheat was determined. These fungi included Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium oxysporum, Fusarium verticillioides, Fusarium solani, Fusarium graminearum, Penicillium digitatum, Penicillium italicum, and Greeneria uvicola. Non-germinated and germinating conidia of these fungi were bioassayed separately. The non-germinated and germinating conidia of all Fusarium species were highly susceptible to the mixture (H1-H4) as well as pure H1, with viability losses of 99-100% found to be significant (p <0.001) at <= 10 mu M or less for the histone mixture and pure H1. F. graminearum was the most sensitive to histone activity. The histones were inactive against all of the non-germinated Penicillium spp. conidia. However, they significantly reduced the viability of the germinating conidia of the Penicillium spp. conidia, with 95% loss at 2.5 mu M. Non-germinated and germinating conidia viability of the Aspergillus spp. and G. uvicola were unaffected when exposed to histones up to 10 mu M. Results indicate that Fusarium spp. pathogenic to wheat are susceptible to wheat histones, indicating that these proteins may be a resistance mechanism in wheat against fungal infection.
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| 7. |
- El-Zanati, S., et al.
(författare)
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Partitions of the 8-Dimensional Vector Space Over GF(2)
- 2010
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Ingår i: Journal of combinatorial designs (Print). - : Wiley. - 1063-8539 .- 1520-6610. ; 18:6, s. 462-474
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Tidskriftsartikel (refereegranskat)abstract
- Let V=V(n,q) denote the vector space of dimension n over GF(q). A set of subspaces of V is called a partition of V if every nonzero vector in V is contained in exactly one subspace of V. Given a. partition P of V with exactly a(i) subspaces of dimension i for 1 <= i <= n, we have Sigma(n)(i=1) a(i)(q(i)-1) = q(n)-1, and we call the n-tuple (a(n), a(n-1), ..., a(1)) the type of P. In this article we identify all 8-tuples (a(8), a(7), ..., a(2), 0) that are the types of partitions of V(8,2).
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| 8. |
- Guzeltepe, Murat, et al.
(författare)
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Perfect Mannheim, Lipschitz and Hurwitz weight codes
- 2014
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Ingår i: Mathematical Communications. - 1331-0623 .- 1848-8013. ; 19:2, s. 253-276
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Tidskriftsartikel (refereegranskat)abstract
- The set of residue classes modulo an element pi in the rings of Gaussian integers, Lipschitz integers and Hurwitz integers, respectively, is used as alphabets to form the words of error correcting codes. An error occurs as the addition of an element in a set E to the letter in one of the positions of a word. If epsilon is a group of units in the original rings, then we obtain the Mannheim, Lipschitz and Hurwitz metrics, respectively. Some new perfect 1-error-correcting codes in these metrics are constructed. The existence of perfect 2-error-correcting codes is investigated by computer search.
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| 9. |
- Heden, Olof
(författare)
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A full rank perfect code of length 31
- 2006
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Ingår i: Designs, Codes and Cryptography. - : Springer Science and Business Media LLC. - 0925-1022 .- 1573-7586. ; 38:1, s. 125-129
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Tidskriftsartikel (refereegranskat)abstract
- A full rank perfect 1-error correcting binary code of length 31 with a kernel of dimension 21 is described. This was the last open case of the rank-kernel problem of Etzion and Vardy.
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| 10. |
- Heden, Olof
(författare)
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A maximal partial spread of size 45 in PG(3,7)
- 2001
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Ingår i: Designs, Codes and Cryptography. - 0925-1022 .- 1573-7586. ; 22:3, s. 331-334
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Tidskriftsartikel (refereegranskat)abstract
- An example of a maximal partial spread of size 45 in PG(3, 7) is given. This example show's that a conjecture of Bruen and Thas from 1976 is false. It also shows that an upper bound for the number of lines of a maximal partial spread, given by Blockhuis in 1994, cannot be improved in general.
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