Über die elastischen Eigenschwingungen endlicher Körper

Ohne Zusammenfassung Vorgelegt von C. Müller     

Microscale NMR screening of new detergents for membrane protein structural biology

The rate limiting step in biophysical characterization of membrane proteins is often the availability of suitable amounts of protein material. It was therefore of interest to demonstrate that microcoil nuclear magnetic resonance (NMR) technology can be used to screen microscale quantities of membrane proteins for proper folding in samples destined for structural studies. Micoscale NMR was then used to screen a series of newly designed zwitterionic phosphocholine detergents for their ability to reconstitute membrane proteins, using the previously well characterized beta-barrel E. coli outer membrane protein OmpX as a test case. Fold screening was thus achieved with microgram amounts of uniformly (2)H, (15)N-labeld OmpX and affordable amounts of the detergents, and prescreening with SDS-gel electrophoresis ensured efficient selection of the targets for NMR studies. A systematic approach to optimize the phosphocholine motif for membrane protein refolding led to the identification of two new detergents, 138-Fos and 179-Fos, that yield 2D [ (15)N, (1)H]-TROSY correlation NMR spectra of natively folded reconstituted OmpX.     

Bioactive textiles by sol–gel immobilised natural active agents

The sol–gel immobilisation and controlled release of various bioactive liquids (BL) from within modified silica coatings were investigated, in order to evaluate the suitability of functionalised textiles for the following applications: (1) skin-friendly textiles with antimicrobial and antiallergic effects due to immobilised natural oils such as evening primrose and perilla oil; (2) textiles for therapeutic treatment of the respiratory tract by means of immobilised mixtures of high volatility natural agents such as eucalyptol, camphor and menthol. Results indicating the antimicrobial properties, washfastness and medical activity of the bioactive textiles are presented. Of note is the transdermal resorption of the BL from the sol–gel coated textiles, determined by the time-dependent concentration of cineol, camphor and menthol in the air exhaled by test subjects after the application of coated textiles. When compared to the application of an ointment, not only does the use of coated textiles offer a more continuous and prolonged release of the embedded BL, but it is also more convenient.     

Influence of ligands on the dynamics of hydrogen elimination in cationic complexes of Co and Rh

The quantum dynamics of beta-hydrogen elimination in cationic transition metal complexes [CpML(C(2)H(4))H](+) (M = Co, Rh; L = PH(3), PF(3), PMe(3), P(OMe)(3)) is studied theoretically. The underlying potential energy profiles are obtained at the DFT level of theory; the nuclear motion is computed by the method of wave packet propagation (i.e., by integrating the time-dependent Schrodinger equation). For the Co as well as the Rh complexes, agostic intermediates relevant to the insertion/elimination process exist. Complexes containing each ligand are studied for both transition metals from an electronic structure point of view and, in addition, the ligand influence on the dynamics is compared. The results allow us to draw conclusions concerning the influence of the energetics as well as the different masses on vibrational periods and lifetimes of these complexes due to beta-elimination.     

Synthesis and properties of oxadiazole based V-shaped, shape persistent nematogens

A series of biaxial V-shaped, shape-persistent molecules has been synthesised by stepwise coupling of phenylene ethynylene arms to an oxadiazole bending unit. Studies of their thermotropic nematic phases point to phase biaxiality.