Home About us Contact
|
Home About us Contact | ||
|
|
||
Various Aromatic Compounds (various + aromatic_compound)
Selected AbstractsBiochemical and molecular characterization of a laccase from the edible straw mushroom, Volvariella volvaceaFEBS JOURNAL, Issue 2 2004Shicheng Chen We have isolated a laccase (lac1) from culture fluid of Volvariella volvacea, grown in a defined medium containing 150 µm CuSO4, by ion-exchange and gel filtration chromatography. Lac1 has a molecular mass of 58 kDa as determined by SDS/PAGE and an isoelectric point of 3.7. Degenerate primers based on the N-terminal sequence of purified lac1 and a conserved copper-binding domain were used to generate cDNA fragments encoding a portion of the lac1 protein and RACE was used to obtain full-length cDNA clones. The cDNA of lac1 contained an ORF of 1557 bp encoding 519 amino acids. The amino acid sequence from Ala25 to Asp41 corresponded to the N-terminal sequence of the purified protein. The first 24 amino acids are presumed to be a signal peptide. The expression of lac1 is regulated at the transcription level by copper and various aromatic compounds. RT-PCR analysis of gene transcription in fungal mycelia grown on rice-straw revealed that, apart from during the early stages of substrate colonization, lac1 was expressed at every stage of the mushroom developmental cycle defined in this study, although the levels of transcription varied considerably depending upon the developmental phase. Transcription of lac1 increased sharply during the latter phase of substrate colonization and reached maximum levels during the very early stages (primordium formation, pinhead stage) of fruit body morphogenesis. Gene expression then declined to ,,20,30% of peak levels throughout the subsequent stages of sporophore development. [source] Development of a gene knockout system for Ralstonia eutropha H16 based on the broad-host-range vector expressing a mobile group II intronFEMS MICROBIOLOGY LETTERS, Issue 2 2010Jong Myoung Park Abstract Ralstonia eutropha H16 is a Gram-negative lithoautotrophic bacterium and is one of the best biopolymer-producing bacteria. It can grow to high cell densities either under lithoautotrophic or under heterotrophic conditions, which makes it suitable for a number of biotechnological applications. Also, R. eutropha H16 can degrade various aromatic compounds for environmental applications. The mobile group II intron can be used for the rapid and specific disruption of various bacterial genes by insertion into any desired target genes. Here, we applied the mobile group II intron to R. eutropha H16 and developed a markerless gene knockout system for R. eutropha: RalsTron. As a demonstration of the system, the phaC1 gene encoding polyhydroxyalkanoate synthase was successfully knocked out in R. eutropha H16. Furthermore, this knockout system would be useful for knocking out genes in other bacteria as well because it is based on a broad-host-range vector and the mobile group II intron that minimally depends on the bacterial hosts. [source] Rock hyraces: a cause of San rock art deterioration?JOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2007Linda C. Prinsloo Abstract San rock art sites are found throughout southern Africa, many showing signs of deterioration. In order to conserve this invaluable heritage, a long-term multidisciplinary project has been launched to monitor the rate of their deterioration and determine the various chemical processes that are possibly contributing to the decay. This study was initiated to establish if Raman spectroscopy could contribute to this project and since rock hyrax colonies live in close proximity to many of these archaeological sites, the possible influence of their metabolic products on the deterioration process was investigated. The precipitates from the urine of rock hyraces were analysed with Raman and Fourier-transform infrared (FTIR) spectroscopy. Where the urine was in contact with the faeces, the precipitates are a mixture of vaterite (a rare polymorph of CaCO3) and the hydrated salt calcium monohydrocalcite (also rarely found in nature). On areas where this contact is at a minimum the common and stable polymorph of CaCO3, calcite, is the main component. SEM micrographs and XRD analysis support the Raman and FTIR results. XRD, FTIR and preliminary GC-MS analyses of hyraceum, the fossilised mixture of faeces and urine, identified an inorganic phase (potassium chloride, with small concentrations of other salts, e.g. vaterite and weddelite) and an organic phase, which is a cocktail of various aromatic compounds, mainly amides, alcohols and acids. These compounds could contribute to the crystallisation of these rare carbonates, as well as other uncommon salts detected on the cave walls, such as syngenite. The presence of phosphates in the urine may further act as a stabilizing agent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effects of the magnesium and chloride ions and shikimate on the structure of shikimate kinase from Mycobacterium tuberculosisACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2007Marcio Vinicius Bertacine Dias Bacteria, fungi and plants can convert carbohydrate and phosphoenolpyruvate into chorismate, which is the precursor of various aromatic compounds. The seven enzymes of the shikimate pathway are responsible for this conversion. Shikimate kinase (SK) is the fifth enzyme in this pathway and converts shikimate to shikimate-3-phosphate. In this work, the conformational changes that occur on binding of shikimate, magnesium and chloride ions to SK from Mycobacterium tuberculosis (MtSK) are described. It was observed that both ions and shikimate influence the conformation of residues of the active site of MtSK. Magnesium influences the conformation of the shikimate hydroxyl groups and the position of the side chains of some of the residues of the active site. Chloride seems to influence the affinity of ADP and its position in the active site and the opening length of the LID domain. Shikimate binding causes a closing of the LID domain and also seems to influence the crystallographic packing of SK. The results shown here could be useful for understanding the catalytic mechanism of SK and the role of ions in the activity of this protein. [source] | ||||||||||