Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Poster: New Instruments and Methods
CPP 11.16: Poster
Montag, 14. März 2011, 17:30–19:30, P2
CIDNP study of cyclic peptides with sulfur containing amino acids — •Talea Köchling1, Gerald Hörner1, Alexandra Yurkovskaya2, and Hans-Martin Vieth1 — 1Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin — 2International Tomography Center of SB RAS, 630090, Institutskaya 3a, Novosibirsk, Russia
Combining NMR spectroscopy with the effect of spin hyperpolarisation opens new ways to get information about structure of radicals and their reaction pathways. A way for creating transient non-thermal signal amplitudes is chemically induced dynamic nuclear polarisation (CIDNP) resulting from the formation of a radical pair of a photo-excited dye molecule and a quencher, e.g. an amino acid residue. The dependence of CIDNP on the external magnetic field allows to determine magnetic resonance parameters (hyperfine coupling constants and g-factor) of elusive radicals. On the other hand from its time dependence with microsecond resolution it is possible to differentiate geminate and bulk processes, so that reaction pathways and rate constants can be extracted.
In the present study, CIDNP results for different peptides containing a combination of methionine, methylcysteine and glycine in aqueous solution at ambient temperature are obtained. By comparing these peptides that differ in their sulfur-backbone-distances and number of thioether units differences in radical structure and reaction kinetics are shown and discussed. In particular, primary and secondary reaction steps are differentiated and rate constants are determined.