Organisation and Recognition of Artificial Transmembrane Peptides
by Ulrike Rost
Date of Examination:2016-08-11
Date of issue:2016-11-15
Advisor:Prof. Dr. Ulf Diederichsen
Referee:Prof. Dr. Ulf Diederichsen
Referee:Prof. Dr. Claudia Steinem
Persistent Address:
http://dx.doi.org/10.53846/goediss-5977
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Abstract
English
A various number of cellular key functions such as signalling and transport are mediated by membrane proteins, which are either adhesively bound to the membrane surface or exhibit transmembrane domains. Many transmembrane peptides accomplish their full function by interacting with each other. The assembly and organisation of these transmembrane peptide helices depend on the lipid environment and/or the interacting species themselves but the processes behind these interactions still need to be fully clarified. In order to apprehend the essentials and molecular details of transmembrane peptides within the lipid bilayer, simple model systems in combination with specific recognition units became of great interest. In the first part of this thesis, the design, synthesis and investigation of a novel 7-azaindole (7-AI) based recognition unit are presented. The fluorescence emission and intensity of the 7-AI chromophore are known to be sensitive to their local environment. The 7-AI building block was further incorporated in a transmembrane model system, i.e. KALP, and analysed by CD- and fluorescence spectroscopy. The results clearly demonstrated the dependence of the modified KALP on its local environment and they present a suitable application of the new 7-AI building block in the field of peptide research as it can be used to verify a successful incorporation of a transmembrane peptide. Transmembrane model systems have been used in many different ways to analyse basic principles of protein-lipid and protein-protein interactions. However, the influences on transmembrane β-peptide helices, which have the advantage of high structural stability and are not easily degraded, are still widely unexplored. Thus, in the second part of this thesis a novel transmembrane β-peptide has been developed that can function as transmembrane model system. This model system is inserted into lipid bilayers in a transmembrane fashion with the central amino acids located at the bilayer midplane, which was investigated by X-ray diffraction studies and X-ray grazing incidence diffraction (GID) analysis. β-Glutamine-mediated association of these transmembrane β-peptides was successfully performed and controlled by temperature and number of β-glutamine residues.
Keywords: Transmembrane Peptides; Transmembrane β-Peptides; Solid Phase Peptide Synthesis (SPPS); 7-Azaindole; Heavy-Atom Labeling; X-ray Reflectivity Analysis; Circular Dichroism (CD) Spectroscopy; Fluorescence Spectroscopy; Fluorescence Resonance Energy Transfer (FRET); Self-Association of Transmembrane β-Peptides; DOPC; β-Amino Acids
