Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 6: SYED: Electronic 2D Spectroscopy from Small to Large Systems II

MO 6.1: Hauptvortrag

Montag, 18. März 2013, 14:00–14:30, E 415

Two-dimensional UV and visible spectroscopy of biological system — •Majed Chergui, Gerald Auböck, Cristina Consani, Roberto Monni, André El Haddad, and Frank van Mourik — Laboratoire de spectroscopie ultrarapide, ISIC-EPFL, CH-1015 Lausanne, Switzerland

We report on 2D UV transient absorption (TA) studies of ferric myoglobins using our recently implemented setup, which operates at 20 kHz with a spectral bandwidth of >80 nm in both pump and probe beams, allowing to cover the broad spectra of aromatic amino acids below 300 nm. Our results reveal a hitherto unknown electron transfer (ET) mechanism from one of the Trp residues to the porphyrin, whilst such deexcitation channels were always attributed to Förster resonant energy transfer (FRET). The implications of this work go beyond the peculiar systems studied here, in that the lifetimes of Trp residues are invariant in all haem proteins (ferrous or ferric), suggesting that Trp-porphyrin ET also occurs in ferrous proteins. They also question the widespread assumption of FRET-mediated decay of Trp in studies of protein dynamics. We will also present our newly developed 2D coherent set-up in the visible and its application to the study of porphyrin dynamics.