Oppidum Stradonice, Josef Ladislav Píč, and Joseph Déchelette

73

Structure of the dimeric N-glycosylated form of fungal β-N-acetylhexosaminidase revealed by computer modeling, vibrational spectroscopy, and biochemical studies

<p>Abstract</p> <p>Background</p> <p>Fungal β-<it>N</it>-acetylhexosaminidases catalyze the hydrolysis of chitobiose into its constituent monosaccharides. These enzymes are physiologically important during the life cycle of the fungus for the formation of septa, germ tubes and fruit-bodies. Crystal structures are known for two monomeric bacterial enzymes and the dimeric human lysosomal β-<it>N</it>-acetylhexosaminidase. The fungal β-<it>N</it>-acetylhexosaminidases are robust enzymes commonly used in chemoenzymatic syntheses of oligosaccharides. The enzyme from <it>Aspergillus oryzae </it>was purified and its sequence was determined.</p> <p>Results</p> <p>The complete primary structure of the fungal β-<it>N</it>-acetylhexosaminidase from <it>Aspergillus oryzae </it>CCF1066 was used to construct molecular models of the catalytic subunit of the enzyme, the enzyme dimer, and the <it>N</it>-glycosylated dimer. Experimental data were obtained from infrared and Raman spectroscopy, and biochemical studies of the native and deglycosylated enzyme, and are in good agreement with the models. Enzyme deglycosylated under native conditions displays identical kinetic parameters but is significantly less stable in acidic conditions, consistent with model predictions. The molecular model of the deglycosylated enzyme was solvated and a molecular dynamics simulation was run over 20 ns. The molecular model is able to bind the natural substrate – chitobiose with a stable value of binding energy during the molecular dynamics simulation.</p> <p>Conclusion</p> <p>Whereas the intracellular bacterial β-<it>N</it>-acetylhexosaminidases are monomeric, the extracellular secreted enzymes of fungi and humans occur as dimers. Dimerization of the fungal β-<it>N</it>-acetylhexosaminidase appears to be a reversible process that is strictly pH dependent. Oligosaccharide moieties may also participate in the dimerization process that might represent a unique feature of the exclusively extracellular enzymes. Deglycosylation had only limited effect on enzyme activity, but it significantly affected enzyme stability in acidic conditions. Dimerization and <it>N</it>-glycosylation are the enzyme's strategy for catalytic subunit stabilization. The disulfide bridge that connects Cys⁴⁴⁸with Cys⁴⁸³stabilizes a hinge region in a flexible loop close to the active site, which is an exclusive feature of the fungal enzymes, neither present in bacterial nor mammalian structures. This loop may play the role of a substrate binding site lid, anchored by a disulphide bridge that prevents the substrate binding site from being influenced by the flexible motion of the loop.</p

Spolupráce s vědami o neživé přírodě v počátcích české archeologie

Článek sleduje počátky vztahů české archeologie k přírodním vědám od 30. let 19. století. Zatímco spolupráce s mineralogií a petrografií se jednostranně omezovala na expertizu (určení surovin kamenných, vesměs broušených artefaktů pro účely evidenčního popisu) a iniciativa v počátcích výzkumu kvartéru a paleolitu od 40. let 19. století vycházela naopak od přírodovědců (geologů a paleontologů) téměř bez aktivní účasti archeologů, vztah archeologie a chemie se naopak vyvíjel k oboustranné spolupráci. Začínal ve 30. letech zkoumáním „spečených valů“, vyšší úrovně dosáhl od roku 1847 na poli chemické analýzy složení bronzových artefaktů, jejímž iniciátorem (jako první v celé tehdejší rakouské říši) a zčásti i aktivním účastníkem byl archeolog prof. Jan Erazim Vocel. Tato činnost trvala do konce 60. let a jejím výsledkem bylo roztřídění a chronologické seřazení bronzů podle poměru kovů v jejich obsahu; v tomto směru se Vocel už v letech 1853–1855 dopracoval k sekvenci vcelku odpovídající dnešnímu stavu poznání. Na prahu pozitivistické epochy tak prakticky naplňoval svoji zásadu přiblížení archeologie k exaktním přírodním vědám

Zvýšení homogenity a plastických vlastností odlitků litých pod tlakem z hliníkových slitin

PrezenčníNeuvedenoNeuveden

Naměřená minima teploty vzduchu na vybraných horských stanicích v Čechách =Minimal air temperatures measured at some mountain stations in Bohemia

101

Methods and procedures for the protection of anthropogenic objects of historical human activities in forests

The methodology focuses on the use of information about identification, documentation and presentation of anthropogenic objects - relics of historical human economic activity in forests,. These information result from linking forestry, heritage conservation and archaeology. Anthropogenic objects in forests are mainly old roads, sites of historical raw material extraction, raw material processing objects, abandoned settlements, signs of past coppice management, etc. The reason for the development of the methodology is the fear of loss (damage) of these objects by forestry activities. exacerbated at present by the processing of a bark beetle calamity of big proportions on a substantial part of the Czech Republic. If we accepted damage tor destruction of these objects, we would also accept a loss of cultural and historical heritage of the Czech Republic

Heritage conservation of the remains of human activity in the forest

The main objectives of the methodology include: 1. setting the issue in the legislative environment; 2. introducing the processes of disturbance of objects in the forest environment; 3. characterization of modern methods of identification of objects in forests; 4. introducing the practical procedure of identification of objects of human activities in forests; 5. proposing procedures for ensuring the preservation and presentation of anthropogenic remains of human activities in forests for state administration and local government. The methodology was developed in cooperation between experts in the humanities and natural sciences. It seeks to apply and combine procedures of different disciplines. The methodology is recommended to be used with methodology Methods and procedures for the protection of anthropogenic objects of historical human economic activity in forests (Kadavý et al. 2022). The two methodologies are complementary to each other

The Eighth Central European Conference "Chemistry towards Biology"

The Eighth Central European Conference “Chemistry towards Biology” was held in Brno, Czech Republic, on 28 August–1 September 2016 to bring together experts in biology, chemistry and design of bioactive compoundspromote the exchange of scientific results, methods and ideasand encourage cooperation between researchers from all over the world. The topics of the conference covered “Chemistry towards Biology”, meaning that the event welcomed chemists working on biology-related problems, biologists using chemical methods, and students and other researchers of the respective areas that fall within the common scope of chemistry and biology. The authors of this manuscript are plenary speakers and other participants of the symposium and members of their research teams. The following summary highlights the major points/topics of the meeting