50 research outputs found
Die Auswirkung von Einzelbindungs-Konformationsänderungen auf die Polyprolin II Sekundärstruktur
No full textDer Polyprolin II-Helix (PP II) wurde, im Gegensatz zu den klassischen Sekundärstrukturen wie α-Helix, β-Faltblatt oder Schleifenstrukturen, bisher wenig Beachtung geschenkt. Dieses Phänomen ist darauf zurückzuführen, dass dieses Sekundärstrukturelement oft als ungefaltet oder "random" Zustand angesehen wurde. In vivo dagegen sind PP II-helikale Polypeptide wichtige Strukturen für die Übertragung zellulärer Signale. Ziel dieser Arbeit war es, erstmalig ein einheitliches Modell zu entwerfen, dass den Einfluss von Einzelbindungs-Konformationsänderungen auf die Polyprolin-(PP) Sekundärstrukturen, unter Einbezug aller bisherigen Literaturdaten, beschreiben kann. Zu diesem Zweck wurden Polyprolinpeptide untersucht, in denen ortsspezifisch das Carbonylsauerstoffatom einer Peptidbindung gegen ein Schwefelatom ausgetauscht war. Dieses erlaubte die Detektion einzelner Peptidbindung innerhalb der untersuchten Peptide, und ermöglichte eine vergleichende Analyse von Photo- und Lösungsmittelinduzierten cis/ trans-Gleichgewichtsverschiebung auf die PP-Sekundärstrukturen. Die Untersuchungen wurden anhand unstrukturierter Dipeptide als auch mit 13 gliedrigen Polyprolin-Peptiden durchgeführt. Diese Studien zeigten, dass PP I- und PP II-Helices nicht an allen Positionen die gleichen Freiheitsgrade besitzen und nur "Idealfälle" darstellen, da verschiedene semistabile Intermediatstrukturen existieren.In contrast to the classical secondary structures, α-helix, β-sheet and turn structures, less attention was paid at the poly-proline (PP) II-helix in the last decade. This phenomenon might be caused by the fact that this structure was often falsely assigned as random or unfolded. However, in vivo PP II structures play an important role for many cell signalling processes. The main goal of this work was to establish a model, including the present literature, which described the influence of single conformational switches on the PP secondary structures. For this purpose we synthesized peptides where a single carbonyl oxygen atom of a 13mer polyproline peptides was replaced by sulphur. The resulting thioxopeptides allowed the detection of structural changes of a single peptide bond within the polyproline-peptides and were used for comparative analyses of photo- and solvent induced cis/ trans isomerisation processes of the PP secondary structures. The kinetic and thermodynamic properties of the different thioxo-polyproline peptides and reference thioxo dipeptides showed that PP I- and PP II-helices do not possess the same degrees of freedom at every position within such a structure. Therefore, the PP I- and PP II-helices represent only an ideal state of such structures.von Stephan Wawr
KARTHAGO
No full text"Literary work by Friedrich Kock-Wawara entitled “Auf Nach Karthago”, which was dedicated by the author to Gen. Plutarco Elías Calles, “The Mexican Mussolini” (See library).
/ Obra de Friedrich Kock-Wawra intitulada ""Auf Nach Karthago"". Fue dedicada por el autor al Gral. PEC, ""el Mussolini Mexicano"" (Ver biblioteca).
Conformational Consequences of Regio‐ and Stereoselective Disulfide Bridge Oxidation in a Cyclic Peptide
No full textTowards understanding the virulence functions of RXLR effectors of the oomycete plant pathogen <i>Phytophthora infestans</i>
No full textPlant pathogens establish infection by secretion of effector proteins that may be delivered inside host cells to manipulate innate immunity. It is increasingly apparent that the ubiquitin proteasome system (UPS) contributes significantly to the regulation of plant defences and, as such, is a target for pathogen effectors. Bacterial effectors delivered by the type III and IV secretion systems have been shown to interact with components of the host UPS. Some of these effectors possess functional domains that are conserved in UPS enzymes, whilst others contain novel domains with ubiquitination activities. Relatively little is known about effector activities in eukaryotic microbial plant pathogens. Nevertheless, effectors from oomycetes that contain an RXLR motif for translocation to the inside of plant cells have been shown to suppress host defences. Annotation of the genome of one such oomycete, the potato late blight pathogen Phytophthora infestans, and protein-protein interaction assays to discover host proteins targeted by the RXLR effector AVR3a, have revealed that this eukaryotic plant pathogen also has the potential to manipulate host plant UPS function
Quality of Service Controlled Multimedia Transport Protocol
No full textPhDThis research looks at the design of an open transport protocol that supports a range of
services including multimedia over low data-rate networks. Low data-rate multimedia
applications require a system that provides quality of service (QoS) assurance and flexibility.
One promising field is the area of content-based coding. Content-based systems use an array
of protocols to select the optimum set of coding algorithms. A content-based transport
protocol integrates a content-based application to a transmission network.
General transport protocols form a bottleneck in low data-rate multimedia
communicationbsy limiting throughpuot r by not maintainingt iming requirementsT. his work
presents an original model of a transport protocol that eliminates the bottleneck by
introducing a flexible yet efficient algorithm that uses an open approach to flexibility and
holistic architectureto promoteQ oS.T he flexibility andt ransparenccyo mesi n the form of a
fixed syntaxt hat providesa seto f transportp rotocols emanticsT. he mediaQ oSi s maintained
by defining a generic descriptor. Overall, the structure of the protocol is based on a single
adaptablea lgorithm that supportsa pplication independencen, etwork independencea nd
quality of service.
The transportp rotocol was evaluatedth rougha set of assessmentos:f f-line; off-line
for a specific application; and on-line for a specific application. Application contexts used
MPEG-4 test material where the on-line assessmenuts eda modified MPEG-4 pl; yer. The
performanceo f the QoSc ontrolledt ransportp rotocoli s often bettert hano thers chemews hen
appropriateQ oS controlledm anagemenatl gorithmsa re selectedT. his is shownf irst for an
off-line assessmenwt here the performancei s compared between the QoS controlled
multiplexer,a n emulatedM PEG-4F lexMux multiplexers chemea, ndt he targetr equirements.
The performanceis also shownt o be better in a real environmentw hen the QoS controlled
multiplexeri s comparedw ith the real MPEG-4F lexMux scheme
Secretion, delivery and function of oomycete effector proteins
No full textOomycetes are responsible for multi-billion dollar damages in aquaculture, agriculture and forestry. One common strategy they share with most cellular disease agents is the secretion of effector proteins. Effectors are molecules that change host physiology by initiating and allowing an infection to develop. Oomycetes secrete both extracellular and intracellular effectors. Studying secretion, delivery and function of effectors will hopefully lead to alternative control measures, which is much needed as several chemicals to control plant and animal pathogenic oomycetes cannot be used anymore; due to resistance in the host, or because the control measures have been prohibited as a result of toxicity to the environment and/or consumers. Here the latest findings on oomycete effector secretion, delivery and function are discussed
Kiedyś Prusa – dziś Ślimaka, czyli o tendencjach nazewniczych towarzyszących zmianom nazw ulic w warszawskiej dzielnicy Wawer
No full textIn 1951, the municipality of Wawer, consisting of several villages, became one of the districts of Warsaw. As a result of an administrative change, many of Wawer’s street names repeated those already recorded in Warsaw, which made it necessary to change them. Based on the juxtaposition of the original names with those found on the map of Wawer today, several trends illustrating the mechanisms of change can be distinguished. The article presents a preliminary proposal for the division of Wawer’s hodonyms according to their relationships with earlier names. The author examines in detail the types of relationships between new and old ononyms and indicates the semantic categories to which current names refer. She also mentions Wawerian hodonyms forming naming complexes and those that were intended to build local identity. The aim of the text is to provide a basis for a more detailed study of the renaming processes of street names.W 1951 roku składająca się z kilku miejscowości gmina Wawer stała się jedną z dzielnic Warszawy. W wyniku zmiany administracyjnej wiele nazw wawerskich ulic powtarzało te notowane już w Warszawie, co spowodowało konieczność ich zmiany. Na podstawie zestawienia pierwotnych onimów z tymi, które na mapie Wawra znajdujemy dziś, można wyróżnić kilka tendencji obrazujących mechanizmy zmian. Artykuł przedstawia wstępną propozycję podziału wawerskich hodonimów ze względu na ich związki z wcześniejszymi nazwami. Autorka szczegółowo zajmuje się rodzajami związków między nowymi a starymi onimami oraz wskazuje kategorie semantyczne, do których odnoszą się aktualne nazwy. Wspomina także o wawerskich hodonimach tworzących kompleksy nazewnicze oraz o tych, które miały służyć budowaniu lokalnej tożsamości. Celem tekstu jest stworzenie podstawy do bardziej szczegółowych badań nad procesami przemianowywania nazw ulic
Auto-aggregation in zoospores of <i>Phytophthora infestans</i>:the cooperative roles of bioconvection and chemotaxis
No full textPhytophthora infestans is a highly destructive plant pathogen. It was the cause of the infamous Irish potato famine in the nineteenth century and remains to this day a significant global problem with associated costs estimated at $3 billion annually. Key to the success of this pathogen is the dispersal of free-swimming cells called zoospores. A poorly understood aspect of zoospore behaviour is auto-aggregation—the spontaneous formation of large-scale patterns in cell density. Current competing hypotheses suggest that these patterns are formed by one of two distinct mechanisms: chemotaxis and bioconvection. In this paper, we present mathematical and experimental results that together provide strong evidence that auto-aggregation can only result from a combination of these mechanisms, each having a distinct, time-separated role. A better understanding of the underlying infection mechanisms of P. infestans and potentially other Phytophthora species will in the longer term lead to advances in preventative treatment and thus potentially significant savings in socio-economic costs
