PH-Bestimmungsmethoden

Ohne Zusammenfassung     

An orthogonal family of polynomials on the generalized unit disk and ladder representations of

Inner product structures are given for realizations of the positive spin ladder representations over the generalized unit disk . This is accomplished by combining previous results of the author with the construction of a family of holomorphic polynomials on . These polynomials, which play a crucial role in the present work, are shown to be orthogonal with respect to Lebesgue measure, and their norms are computed. The orthogonal family is then used to invert a certain integral transform, giving the desired inner product structures.

     

Isothiocyanato-calix[4]phyrin-(1,1,1,1): a useful intermediate for the synthesis of derivatised anion sensors

A calix[4]phyrin-(1,1,1,1) substituted with a 4-isothiocyanatophenyl group has been synthesised and used to attach the macrocycle to a solid support. The NCS group can also be used to further functionalise the calix[4]phyrin-(1,1,1,1) by reaction with amines and amino acids. Stability constants for anion binding by the calix[4]phyrin-(1,1,1,1) are reported and these show a clear ability to differentiate F(-) and HSO(4)(-) from Cl(-), Br(-), I(-) which can be detected by both NMR and UV-visible spectroscopy.     

Dynamic nuclear polarization-enhanced solid-state NMR of a 13C-labeled signal peptide bound to lipid-reconstituted Sec translocon

Dynamic nuclear polarization (DNP) has made it possible to record 2D double-quantum-filtered (DQF) solid-state NMR (ssNMR) spectra of a signal peptide bound to a lipid-reconstituted SecYEG translocon complex. The small quantity of peptide in the sample (~40 nmol) normally prohibits multidimensional ssNMR experiments. Such small amounts are not the exception, because for samples involving membrane proteins, most of the limited sample space is occupied by lipids. As a consequence, a conventional 2D DQF ssNMR spectrum with the sample used here would require many weeks if not months of measurement time. With the help of DNP, however, we were able to acquire such a 2D spectrum within 20 h. This development opens up new possibilities for membrane protein studies, particularly in the exploitation of high-resolution spectroscopy and the assignment of individual amino acid signals, in this case for a signal peptide bound to the translocon complex.     

Anodic phenyl-onium cation formation: Part II. Reaction mechanism and optimization for the anodic formation of diphenyliodonium cations

The anodic coupling of iodobenzene and benzene to the diphenyliodonium cation is shown to be based on attack of an iodobenzene radical cation on a benzene molecule at the anode surface. Only on platinum anodes in acetonitrile solutions the respective adsorption conditions of benzene and iodobenzene are so favourable that a self coupling to the iodophenylphenyliodonium cation can be avoided. According to the predictions which are based on the electrode kinetic investigations, optimal conditions for the coupling are: (1) low working temperature, (2) low working potential (i.e.c.d. around 18–20 mA cm^?2), (3) high iodobenzene/benzene ratio in the bulk of the solution. Under these conditions 85% current efficiency and 95% mass yield for the coupling are obtained.