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CPP: Chemische Physik und Polymerphysik

CPP 25: POSTER Electronic Structure and Spectroscopy

CPP 25.6: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

CIDNP and ¹⁹F-¹H Spin Polarization Transfer in 3-Fluorotyrosine — •Sergey Korchak¹, Vitor Nascimento de Carvalho Pinto¹, Konstantin Ivanov², and Hans-Martin Vieth¹ — ¹Department of Physics, Free University of Berlin, Arnimallee 14, D-14195 Berlin, Germany — ²International Tomography Center of SB RAS, 630090, Institutskaya 3a, Novosibirsk, Russia

The transfer of dynamic spin polarization between different nuclei in biological molecules can be used for labeling specific nuclear positions and applied to NMR spectroscopy in biology and medicine or for sensitivity enhancement in magnetic resonance imaging. Here, we report on strong Chemically Induced Dynamic Nuclear Polarization (CIDNP) created in reversible photoreactions between biological molecules and triplet exited dyes involving transient radical pairs. In particular, the ¹⁹F-¹H polarization transfer in CIDNP experiments with 3-fluoro-DL-tyrosine is examined by means of ¹⁹F-CIDNP and ¹H-CIDNP. For the first time, the magnetic field dependence of ¹⁹F-CIDNP at 0-7 T is obtained. The mechanism of polarization transfer is revealed and optimum conditions for getting high spin polarization transfer are discussed. By comparing the experimental results with model calculations the g-factor of the 3-fluorotyrosine radical is obtained. The fluorinated amino acids incorporated in proteins may be used for the investigation of protein folding with the advantage that fluorine exhibits a higher CIDNP effect than proton and that the background ¹H polarization is absent.