[No abstract submitted] / Arts, Faculty of / Classical, Near Eastern and Religious Studies, Department of / Graduate

Thesis (M.A.). / Written for the Dept. of Music Research, Schulich School of Music. Title from title page of PDF (viewed 2008/05/13). Score preceded by analysis. Includes bibliographical references.

Thesis--University of Iowa. / Includes bibliographical references.

Les cycles peptidiques (CPs) composés d’un nombre paire d’acides aminés avec l’alternance de chiralité L/D, sont capables de s’auto assembler pour former des nanotubes peptidiques tubulaires creux grâce à un réseau de liaisons d’hydrogène. La partition des CPs hydrophobes dans une membrane lipidique forme un nanotube transmembranaire, alors que les CPs chargés caractérisé par l’amphipacité montrent une forte activité antibactérienne contre les bactéries gram+/-. Le but de ce travail consiste principalement à étudier les interactions des CPs avec des membranes lipidiques par simulations de dynamique moléculaire utilisant l’approche gros grains, pour mieux caractériser le processus d’auto assemblage, la formation de nanotubes transmembranaires et l’action antibactérienne des CPs. Les résultats obtenus montrent que l’activité de CPs est gouvernée par les propriétés physico-chimiques de la l’interaction des CPs avec les têtes polaires de la membrane. Dans le cas des CPs hydrophobes, les peptides s’auto-assemblent en amas à la surface des membranes avant de s’auto organiser à l’intérieur des bicouches lipidiques pour former des nanotubes transmembranaires. Dans le cas des CPs chargés, leur action antibactérienne semble résulter de l’extraction et la libération de micelles de phospholipides de la membrane qui est précédée par l’adsorption des peptides à la surface des membranes en mode dit carpet-like. L’ensemble de cette étude a nécessité un grand effort d’optimisation des champs de forces gros grains existants. Nous avons en effet montré leurs limites et optimisés les paramètres d’interaction impliquant plusieurs acides amines comme les résidus Leu, Trp, Arg et Lys. Nous avons étendu l’étude au repliement de peptides hélicoïdaux transmembranaires et antimicrobiens montrant ainsi la transférabilité du champ de force GG optimisé. / Cyclic peptides (CPs) composed of an even number of alternating D and L amino acids, are able to self-assemble into hollow tubular peptide nanotubes by means of a network of hydrogen bonds. The partition of hydrophobic CPs in lipid membranes forms an artificial transmembrane nanotube, while charged CPs characterized by amphipathic properties exhibit high antibacterial activity against Gram-positive and Gram-negative bacteria. The main goal of our investigation consisted to studying the interaction of cyclic peptides with lipid membranes using coarse grained molecular dynamics simulations in order to characterize the process of self assembly in solution, formation of transmembrane nanotubes and antibacterial activity of cyclic peptides. The results obtained revealed that, the activity of these CPs are governed by their physicochemical properties and by the interactions with the membrane lipid head-groups. In the case of hydrophobic CPs, the peptides pre-assemble as clusters before re-organizing in the interior of the membrane to form transmembrane nanotubes. For cationic CPs, the antibacterial activity seems to result from a release of phospholipid micelles following a carpet-like model adsorption. This study required a large effort in optimizing the coarse grain force field published so far. We have indeed shown their shortcomings, and optimized the parameters describing the interactions involving several amino-acids such as Leu, Trp, Arg and Lys. We have extended the study to the investigation of the folding of transmembrane and antimicrobial peptides probing hence the transferability of the optimized coarse grained model force field.

Thesis (Ph. D.)--University of Oregon, 2000. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 179-182). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xi, 94 p.: ill. Includes abstract and vita. Advisor: Nelson C. Mark. Includes bibliographical references (p. 91-94).

Thesis (Ph. D.)--Michigan State University. Dept. of Economics, 2008. / Title from PDF t.p. (viewed on July 7, 2009) Includes bibliographical references (p. 89-91). Also issued in print.

Thesis (M.S. in Physical Oceanography)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): Chu, Peter. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Mine Warfare, Route Survey, Bedforms, Waves, Tides, Currents, Survey Periodicity, Sediment Transport, Sediment Dynamics, Bathymetry, GIS, Weighted Suitability Model, San Francisco Bay. Includes bibliographical references (p. 99-102). Also available in print.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 126-139).

Issued also as thesis, Berlin. / Neue deutsche Forschungen, Bd. 290. "Verzeichnis der benutzten Schriften": p. [126]-129.